| Author |
Message |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 191
Registered: 5-2002
| | Posted on Thursday, July 04, 2002 - 8:17 pm: | |
If you make up new hoses for a 308 and make them a little longer. I have ran them through the channel under where they are ran now. No need to remove gas tank.Can get in through wheel panels.Plenty of room. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 15
Registered: 5-2002
| | Posted on Thursday, July 04, 2002 - 12:34 am: | |
hi octavio,
it wasn't that bad (cough-cough) :-)
oddly, I took a 308 in a week later and when putting in the last .05Kg of freon, the high pressure hose blew. exactly the same problem...hose rubbing against the body/frame wore a divot in the rubber, and the pressure blew it out. the low pressure hose also had a couple wear spots.
also, the low side hose and the evaporator had a lot of nasty oil accumulated in it. disconnected low side hose at the expansion valve and blew compressed air through back to the compressor end.
what came out can fairly accurately be be described as pus, so make sure you have a rag over the hose end to catch it all.
I wound up replacing both the high and low hoses. had them made up at a radiator shop for $50 each. the hoses route through a frame tube under the passenger side. on the 328, it took three of us to get the high pressure hose fished through. on the 308, I did both hoses myself in about 20 minutes - not counting how long it took to remove enough things to get at the hoses (mainly the gas tank).
here's what I did:
- put car up on jackstands, remove passenger side front/rear wheels and wheel well liners
- drain fuel - I took off the fuel hose between the drivers-side tank and the fuel pump because it needed replacing anyway. there is a drain plug on the bottom pipe between the two tanks
- remove passenger side rear brake rotor. I don't think the tank will come out with the rotor in place. note that on the 328, we didn't do this and just left the tank in the wheel well. it was in the way a bit
- disconnect hoses from the gas tank. some of the smaller hoses are easier to remove once the tank is unstrapped and you can move the tank around a little. for the big hose at the bottom, loosen and slide the clamps out of the way and then rotate the hose with a rag while slidng the hose off the tank fitting.
- remove nuts from ends of the straps holding in the tank. if you can't get your arm along side the tank to get at the horizontal strap, find someone with a thinner arm :-) remove the gas tank. you need to rotate the tank around a bit to get it out.
- disconnect hose(s) at the condensor (high side) and expansion valve (if replacing low side).
- tie 1/8" rope to fittings - you will need this later to pull the new hose back in. on the 308, the high side hose routes behind one of the heater boxes, and it can take a bit of fiddling to pull/push it through. I first fished it out from behind the heater box, then pulled it down into the wheel well.
- untie/cut the rope - you should now have a rope segment threaded along the route the new hose needs to go from the front wheel well to wherever it connects in front. the hose should be dangling out of the square frame tube into the wheel well.
- go to the rear wheel well. measure how much hose is between the hole in the frame and the compressor (so you know when to stop feeding in the new hose). if you are replacing the low side hose, make your life easy and cut the low side hose near where it disappears into the frame (behind where the gas tank was). go to the front and pull the hose out. note you cannot pull this hose out with the rear fitting still attached. if you are just replacing the high side hose, I'd cut he high side hose then punch a hole in the hose and thread either the rope or some string in. then go to the front and pull out the high side hose, pulling the string/rope through with it. if you used string, tie rope to the string and pull the rope through next. if you are installing both hoses, pull through two strands of rope...you'll need one for each hose.
- if you removed both hoses, install the low side hose first. to install the hoses, tie the rope behind the fitting on the hose end, and up in the passenger wheel well, loop the rope over the rotor and run it back to the rear wheel well. the rotor will act like a pulley.
- ok, now the trick to this whole process. the hoses enter a rectangular hole behind the gas tank more or less side-by-side. they run down, jog LEFT and enter an oval hole in the top of the frame tube, then make a 90 degree bend and go forward. if you have a mirror, look around the right side the metal frame near the bottom...you can see the hoses coming down and entering the oval hole (assuming you look before you pull out the hoses :-)) the long axis of the oval is parallel to the length of the car, so one hose is in front of the other hose going into the oval hole. anyway, what you do is pull lightly on the rope and push the hose into the upper hole. as the hose end heads down, stick your fingers around the right side of the metal frame and push the hose end left and guide it into the top of the oval hole. once the hose is bottomed out in the tube frame, pull on the rope to make the fitting turn the corner while pushing on the hose. it pretty easily goes in - at least, it does if the low side hose is in FRONT of the high side hose. if it isn't, I'd suggest you pull the low side hose from the front of the car so it is snugly up against the front of the oval hole, then route the high side hose behind it. keep pulling and pushing to feed the hose all the way through.
- use the front piece(s) of rope to fish the hose(s) the rest of the way up to where they connect, reinstall everything
disassembly was a couple hours, and reassembly took about four, since I replaced some fuel line and needed to bleed the brakes (you have to open the brake line on the '80 308 to remove the rotor).
life is easier if you can fit inside the wheel well (another reason to remove the rotor). this makes sticking your finger behind the frame to manipulate the hose ends easy, and you just sit in there with your legs stretched out forward while pushing in the new hose and pulling on the rope.
I used some 1" coolant line as a jacket around the new a/c low side hose to keep it from contacting the frame near the compressor. the high side and fuel hoses I routed underneath the low hose so they can't get gouged in the future. |
Octavio Mestre (Alfab4308)
Junior Member
Username: Alfab4308
Post Number: 55
Registered: 7-2001
| | Posted on Tuesday, July 02, 2002 - 8:46 pm: | |
Holy **** Phil. I planned to put a new compressor, drier, and a second condensor in my Alfa Spider next week but now I'm scared! I hope I don't go through half what you did. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 12
Registered: 5-2002
| | Posted on Thursday, June 20, 2002 - 8:39 pm: | |
hi bruno,
I was there the whole time. the low side can't pump down becuase the charging machine is trying to inject freon in at around 100psi the whole time.
the charging system filled the low side with .25kg of freon, and due to the obstruction, no freon flowed backwards through the expansion valve to fill the high side. when the compressor was turned on, some of the freon pumped to the high side, but it was replaced by the charging machine, thus keeping the low side at around 100psi. as edward said, when the high side reached 100psi, the two halves of the system were balanced, and nothing else happened.
it's also possible that during vaccuum, the crud flowed back and blocked the shrader valve, so the system was never pumped down as indicated by the pressure gauge. |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 135
Registered: 5-2002
| | Posted on Thursday, June 20, 2002 - 10:25 am: | |
Glad to hear it's fixed. The solution does not match your indications however. Any restriction at expansion valve would have caused sytem to pump down.With what you told me, I'd of expected readings of 80 high side 0 to-20" low. But it's fixed and that is all that matters.
(did you see this repair done or did the shop get it going and tell you thats what it was?) |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 10
Registered: 5-2002
| | Posted on Thursday, June 20, 2002 - 3:01 am: | |
hi all,
I'm now freezing to death. the problem turned out to be crud and/or excess oil in the low pressure line between the expansion valve and the compressor, with the bulk in the line between the evaporator and compressor. I'm sure if I go back and read everyone's comments carefully, that conclusion is in there someplace :-(
since I blew the system out early in this little adventure, how did this happen? well, the a/c guy noticed that if you look in the evaporator down the pipe from the expansion valve, there is another orifice in there. I got lazy and didn't disconnect all the lines when shoving through the compressed air, and I was blowing from the compressor end of the hoses. what I apparently did is flow air over/around whatever was in the hose, rather than forcing it out, and the little built-in orifice restricted the air flow helping to prevent a good flush. when the a/c charging system was shoving liquid freon into the low side, it pushed the excess oil and crud up through the evaporator and jammed it against the orifices at the expansion valve. the compressor was then pushing things the other way around and nothing was really moving past the expansion valve.
I guess if the charging system was using a much lower pressure, the compressor would be creating a higher pressure than the charger was putting onto the low side, and it's possible the charge would have slowly worked it's way in.
it was necessary to replace the expansion valve since we basically misadjusted the first one (when the orifice is too small, the valve freezes because the expansion valve doesn't regulate the flow of freon correctly). I suppose by trial and error the close-enough setting would have been reached eventually (remove valve, tweak adjustment, reinstall, evacuate, charge, test, reclaim freon, repeat - done sometime next week).
the good news for all you guys is that here's a generic expansion valve part number that bolts right into the system (and works - I get a little less than 40 degrees at the vents at around 3500 rpm):
208-203 / AC3851C
$25
replacement for:
four seasons : 38610
everco : A8296
of course, it's probably pretty rare for an expansion valve to go bad. the screen on the input line from the drier may clog, but there isn't much in there to really break.
thanks for all the help! next week it's time to take the ex's 308 in for a/c charge after bolting in a new compressor and drier (here we go again :-))
one last tip - to get the compressor out on my car you need to slide it past a stud coming through the cam belt cover - I think it's the stud for the a/c belt tensioner. assuming you don't want to remove the stud, you must pry out the rubber bushings from the top compressor mounting bracket after taking off the nuts. this allows you to shift the compressor close enough to the gas tank to clear the stud. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1499
Registered: 2-2001
| | Posted on Wednesday, June 19, 2002 - 4:39 pm: | |
I am with you Bruno, I believe this machine is creating a loop and equalizing the pressures somehow. At least a pound should go in at room temperature with the compressor off. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1498
Registered: 2-2001
| | Posted on Wednesday, June 19, 2002 - 4:37 pm: | |
Most compressors will operate in any direction as they are basicly two cycle engines. The only difference would be if the compressor has an oil pump as the GM A-6 has and in that case direction is important. |
Bob Campen (Bob308gts)
Junior Member
Username: Bob308gts
Post Number: 241
Registered: 9-2001
| | Posted on Wednesday, June 19, 2002 - 11:58 am: | |
This may have already been taken into account, but with the way the compressor mounts on a 308/328 it would be turning CCW vs the engine rotation of CW. |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 127
Registered: 5-2002
| | Posted on Wednesday, June 19, 2002 - 10:31 am: | |
Can they evacuate and charge without the machine???? That machine should have no trouble putting the freon in. The amount you are telling me it accepts is way to low. A empty vacumed system of that size should take almost all of the charge. Is the machine charging in vapor or liquid. You should be charging in liquid with the compressor off. I would love to see this thing. At this point I must say it sounds like the compressor but to be sure would recommend charging the system with a manifold,freon,scale.
When the shop charges other cars how much freon can it put in before the compressor must be run?
Clarifications:
Where is the pressure reading when the machine says run compressor?
Then it goes to 100 with the compressor on and stops?
Air is non-condensable.
If you run the system empty with hi and low gauges on you should see a differential between the gauges. The low side can even run into a vacum .This will prove the compressor pumps. If it pumps something else is going on.
I am starting to question the reclaim machine (commercial charging machine).
The only way the system can be at 100 psi with the compressor running on both the suction and discharge sides is if the valves are bad in the compressor.Bad valves is not unusual. They are very thin pieces of metal. Reed valves.
|
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1496
Registered: 2-2001
| | Posted on Wednesday, June 19, 2002 - 10:19 am: | |
I would remove both lines from the compressor and force compressed air into the high side and see how much resistance is applied. There should be a fair amount with it also being able to escape from the low side. This is too simple a system to be having this much difficulty. You should also be able to charge at least 1 lb of freon before turning on the compressor. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 9
Registered: 5-2002
| | Posted on Wednesday, June 19, 2002 - 7:03 am: | |
hey bruno,
lemme rephrase some things:
the attempts to charge the system are being done at an a/c shop using a commercial charging system, not cans of r-12. the charging system pumps down the system before injecting freon, and when it does switch to inject mode, it's only getting .1-.25kg in (1kg = 2.2 pounds). at this point, the machine stops and says the compressor needs to be run. when the car is started and the compressor turns on, the high side raises to around 100psi. since the entire system is now at 100 psi, no further freon is pulled/forced into the system. what should happen is the low side drops to around 20-30psi, and the high side goes up around 180psi.
the freon is getting injected into the low side at around 100psi, and since it's a machine, it maintains that pressure.
while it does seem like the compressor is the problem, this is the second new/rebuilt compressor and clutch with the same symptoms. with the
system open, the compressor can develop at least 180 psi into a hose that has it's end plugged.
also, the low side on the compressor is sucking.
I don't know if we ever ran the system without any freon in it with gauges connected to the compressor. I'm not sure what the expected results should be. the high side gets the pressure from shoving liquid freon into the expansion valve. since air doesn't liquify at these low pressures, the expansion valve is going to simply pass the air through. I wouldn't expect much of a pressure difference with just air in the system. could be wrong.
|
Hans E. Hansen (4re_gt4)
New member
Username: 4re_gt4
Post Number: 37
Registered: 4-2002
| | Posted on Tuesday, June 18, 2002 - 7:03 pm: | |
Reverting to a comment made in the original post (now partially off-topic):
The PO of my car stuffed a tennis ball under the A/C hose where it rubs going over the frame rail to protect against abrasion. After 27 years, it's still there! |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 123
Registered: 5-2002
| | Posted on Tuesday, June 18, 2002 - 10:38 am: | |
Also from a 29" vacum you should be able to weigh in 2.2 .lbs without running the compressor. If you have trouble heat the can in hot water first.
After you dump the freon in. How much are you putting in initially??
Now with the car and a/c off after you dump it in assuming you dump it in both sides what does the gauges say they should be about the same. When you now start the car and turn on the a/c what do they do. Where do they go.Do They always stop at 100 each???
|
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 122
Registered: 5-2002
| | Posted on Tuesday, June 18, 2002 - 10:34 am: | |
Turning the tx (expansion valve ) was a mistake. You dont set by pressure yopu set by superheat!!! You will need an experienced Refrigeration tech to reset that valve or buy a new one that is factory set. It is NOT AN OBSTRUCTION IN THE SYSTEM.All indications are compressor is not running. Or you are not tapped into compressor correctly (tapped in hi side,bad schraeder bad hose etc.If you are tapped in correctly and you get the same stagnant 100 psi reading at both gauges then the compresor is not running or running with bad valves and not pumping. Also you musty evacuated system from both sides high and low. not just low. Also 29" is not enough. You should be able to pin that gauge against the stop if the system has no leaks.Is the vacum pump good. As to amount of freon. I know my 308 holds 2.2 lbs.Take all the freon out like I said and run the compressor and tell me what the hi and low side do and I will tell you what the problem is.You will have to hook the 12v up direct to bypass pressure switch. |
Stanley DiGuiseppi (Standig)
New member
Username: Standig
Post Number: 23
Registered: 5-2002
| | Posted on Tuesday, June 18, 2002 - 7:46 am: | |
When charging an A/C system you install by pounds. How many pounds of freon did you put in?
If the pressure reading with a/c off is 100 psi on both sides what does it change to when you engage compressor? |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 8
Registered: 5-2002
| | Posted on Tuesday, June 18, 2002 - 4:03 am: | |
today's results:
disconnected the hose at the drier input and wasn't happy with the pressure the compressor was developing, so starting at the compressor and working forward disconnected/reconnected hosts at each point and verified that the compressor was building pressure. By the time we got forward to the drier input, airflow seemed better, may have been some crud in the condensor that got blown out.
hooked everything back up, evacuated system to -29psi, and tried putting in freon. same result.
removed expansion valve and as an experiment adjusted it so the compressor would develop 180psi before the orifice opened enough to reach steady state. put everything back together - same result.
so down to two things...flush the entire system in case there is a partial obstruction affecting things, or consider whether the entire charging process makes sense.
the way the charging is being done is to evacuate the system via the low side to a small vaccuum, then inject the freon into the system at around 100psi. I assume what then happens is the low side developes 100psi of pressure, at which time the engine is started, the compressor engaged, and the high side pressure rises until it reaches 100 psi.
once the high side == the low side, nothing else happens. apparently this method normally works great - the low side normally drops to around 20-30 psi, the high side goes to around 180psi, and the freon easily shoots into the low side.
seems like the compressor would have to work to overcome not only the orifice in the expansion valve, but the high pressure in the low side. maybe more freon could be injected if the low side pressure put on by the charging machine was reduced? In any case, the system still does not work as expected, and based on bruno's comments, could a partial obstruction in the system could be the cause?
oh, and we now have an expansion valve that is probably misadjusted slightly. according to the theory, if the orifice is too small, what effect does it have? |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 106
Registered: 5-2002
| | Posted on Monday, June 17, 2002 - 10:23 am: | |
Added info.
A lot of people think that when they get high pressure readings at a compressor service valve that they have a blockage or such in the system . Nothing could be further from the truth. If you get a restriction of anykind within the refrigerant system it will give you ,lower high pressure readings and lower suction readings and depending on the severity can even cause the suction side to run in a vacum thus giving you the illusion of no freon in system,Then someone puts in more freon and blows out a compressor,or line,or condenser coil. If you have high readings it is either to hot,fan motors not running in front of radiator, to much freon,non-condensables or blocked (externally) dirty condenser. my extra 2 cents. |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 105
Registered: 5-2002
| | Posted on Monday, June 17, 2002 - 10:17 am: | |
If the schrader valve is giving you a reading of 100 then it is letting you into the system .But I would change it because it is so easy to do. Also use a different hose on you manifold to confirm the depressor is o.k. The oil is required for lubrication and some sub-cooling you have not run this thing long enough to effect either yet. Dont evacuate by time. evacuate by inches on gauge or by micron gauge if one is available.I would not worry about the drier if purging. We always purge systems with nitrogen which will absorb any moisture on the way through and has a high working pressure.If compressor does indeed run take freon out,change shraeder valve and hose on manifold that you are charging with to the low side,run with direct 12v hookup with NO FREON IN SYSTEM,if it does not pull a vacum compressor is bad...Also there wasnt any plastic shipping plugs in this compressor that maybe somebody forgot to remove before they installed??? |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 6
Registered: 5-2002
| | Posted on Monday, June 17, 2002 - 9:28 am: | |
hi all,
good info. the current compressor in the car is the york 258108 from napa.
the attempts to charge the system are being done at an a/c shop where the system is being vaccuumed (30-45 min, verified as having no leaks, and the freon is recovered immediately after the failures. not using cans of r-12. the r-12 is sourced from a machine that is using propane-style tanks of the stuff, and the machine can generate up to 150psi of pressure into the low side. the fact that the machine has this much pressure and the freon isn't getting into the system is pointing to the schrader valve on the low side possibly being bad.
the clutch is working (i have even run a wire directly from the battery to it to bypass the cutoff switch and also deal with a low voltage situation that was originally there due to crud on the metal blades on the fuse in the fuse panel).
the clutch can be heard to activate, and visually you can see the entire assembly rotating after the clutch engages. assuming the clutch is not somehow slipping (the woodruff key is definitely installed on the compressor shaft), then the compressor shaft is turning.
the first compressor may have had insufficient ester oil. the guy who installed it was under the impression that the thing shipped with oil in it. maybe it did, but the compressor from napa just had some assembly oil in it, and it was necessary to add 11oz of ester oil. so the question here is whether the oil level in the pump has any impact besides lubrication?
I think it's down to verifying the schrader valve and compressor first. sounds like simply removing the input line to the drier and running the compressor should result in air flow out the hose. if the open drier input is plugged, then a vaccuum should form in the low side. I suppose to be kind to the dessicant, the drier should be taken out of the loop while sucking air into the system. it took months to get a new drier, so I don't really want to replace it again. anyone know of a cross to an easy to find unit?
I hope to have an answer tuesday night. monday I will try and check the compressor, and tuesday it's back to the a/c shop where the fittings on the compressor will get swapped and we try again - assuming the compressor is pumping.
|
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 104
Registered: 5-2002
| | Posted on Sunday, June 16, 2002 - 9:53 pm: | |
PS:
Any restriction in the system or lines would cause the system to (pump down) meaning the suction would go to almost no pressure or maybe even a vacum and the discharge would stagnate somewhere .If the condenser was blocked (from the outside not within. within the above applies) the suction would rise slightly (at 85 degree day in idle to 50- 70 .lbs and the discharge would climb to 200 and more depending on amount of freon in syatem. |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 103
Registered: 5-2002
| | Posted on Sunday, June 16, 2002 - 9:47 pm: | |
AS AN HVAC ENGINEER I WILL SAY THIS:
1- Did you evacuate the system to at least 30".
If yes
2-Then you should have been able to weigh in almost all of the charge(if you soak the can of refrigerant in hot water first all of the charge)with the compressor off.
3-If the the compressor was operating and you got 100 psi at each service valve that represents bad valves in the compressor. It is not the expansion valve,accumulator , condenser or any of those parts up front.
4- Take all refrigerant out. (you are suppose to be EPA licensed to reclaim it) and bypass the low pressure switch up front. The compressor should run and pull into a vacum on the low (suction) side.If it does not pull a vacum it either isnt on or Bad valves in compressor. If it does pull a vacum .Evacuate(vacum pump) the system again and put the freon in as described above.You should be able to confirm the compressor coming on and turning by watching the tach in the car when you turn it on as soon as the clutch engages the tach should move.
The compressor is nothing more than a pump it pumps hot gas (freon) to the condenser where it cools it (condenses)into a liquid.It then goes to a restricting device (expansion valve) which causes it to expand into a vapor which is subcooled. It then absorbs the heat passed through the evaporator by means of the heater/air conditoner blower fan thus absorbing the heat and finnishing the transformation into a saturated vapor and is sucked back down to the compressor to start over. The accumulator is just that it accumulates excess liquid refrigerant to prevent it from slugging back to the compressor thus destroying the valves over time and washing out the oil.The high side of the sytem is from the discharge of the compressor to the inlet side of the expansion valve. The low side is from the outlet side of the expansion valve to the suction valve of the compressor.
If you need more help or have any questions please post. I am sure I can figure it out for you. Where r u located?
Also my 308 sliced the same line in the same spot! |
Stanley DiGuiseppi (Standig)
New member
Username: Standig
Post Number: 21
Registered: 5-2002
| | Posted on Sunday, June 16, 2002 - 9:08 pm: | |
The compressor takes low pressure vapor and changes it to high pressure vapor. It then go to condenser and changes from vapor to liquid. Then as a high pressure liquid it goes thru the expansion valve to the evaporator and comes out as a low pressure vapor. Are you sure the compressor clutch in engaged? Are you sure the compressor turns in the right directions. If your readings are 100psi on both low and high side it seems like the system in not engaged. Do the readings stay the same after you start and engage clutch? If so it sounds like the compressor is not compressing. If with no freon in the system you open the high side you should feel pressure or air push out of high side if compressor is working.
I know some people push shop air through hoses but it is not generally a good idea. We use a flush which leave almost no air in the system.
Now you may have a problem with heat transfer with would make the system inefficent but you should have a pressure differencial to start with.
I believe you said you tried 2 compressors. Are you sure they are right. If it has a gm type compressor design the reed valve will not open if turned in reverse therefore no pressure. So lets go back to basics.
The compressor has to put out pressure on the high side and suction on the low side. Even if you have to disconnect the hoses at the compressor you should have a pressure out the high side. Start there.
Let us know. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1479
Registered: 2-2001
| | Posted on Sunday, June 16, 2002 - 5:21 am: | |
All your assumptions are correct and your theories are sound. The condenser and hot vapors are cooled by the radiator fan{s}. If they do not work then the system will not function properly and excess high pressure will result. The cooler the condenser is kept, the cooler the evaporator will be. You should be able to take both hoses off the compressor and blow compessed air through the discharge hose and have a restricted feel to it but there should be a return of the air from the suction side. The only way a condenser can go bad would be for it to leak or become restricted which the latter I have never seen happen. Make sure there are no internal check valves in the compressor fittings such as some GM cars have that could restrict the freon charging. Other than that I don't know of anything else that I can tell you without personally seeing the car. You can also feel along the hoses after charging the system to see if there are any cool spots along the way indicating a restricted area. The Drier should be warm on the inlet and outlet sides too with everything functioning normally. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 5
Registered: 5-2002
| | Posted on Sunday, June 16, 2002 - 1:38 am: | |
hi ed,
I was going by the suction/discharge stampings
on the top. discharge goes to the smaller hose
with the 90 degree bend, and suction to the
larger hose with the straight fitting. I
also checked when the expansion valve was off that blowing air through the hose with the 90 degree bend comes out the line from the drier, which
makes sense (discharge == high side). of course, what makes sense to me may not be right :-)
If I disconnect the line at the drier coming from the condensor and run the compressor, should I get
air flow out? do I need to disconnect the low side at the compressor as well? I don't know what the difference is between pumping air and freon, and what effect the expansion valve has on air. Should it be possible to blow compressed air through the system at the compressor lines (i.e. in the high side comes out the low side, and what psi should be
necessary before the orifice in the expansion valve actually restricts the airflow).
if I disconnect the line at the drier and plug the input to the drier, I assume a vaccuum should form in the low side if the compressor is run which should be measurable on the low side compressor fitting.
at his point, I'm trying to figure out tests that can be done to isolate sections of the system. I do have another old compressor from a 308, but swapping compressors is getting a little tedious. at least I found out that with the car tipped up on a jackstand, you can get a compressor out without losing much/any coolant. the top of the coolant pipe needs to be pulled to get access to the belt tensioner nut, but the bottom of the pipe can stay connected and the compressor can be removed without removing the pipe.
finally, from what I've read poking around the net, the freon enters the condensor as a hot gas and comes out as a liguid. if the condensor cannot remove the heat, I guess it would come out as a gas still. is that even possible, and what effect would it have? this is kinda leading to a question about how the condensor is cooled. I'm guessing there is a fan, but I didn't hear one operating and haven't looked yet. if there is a fan, and it's not running, what effect would that have?
I still don't know if the problem is:
- the compressor not pumping,
- compressor is just freely circulating the stuff around a system that has no ability to restrict flow (the freon never enters liquid state, so its flow doesn't get restricted by the orifice in the expansion valve). no restriction==no pressure difference.
note I just made up the second case...don't know if it's technically correct :-)
thanks,
phil |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1474
Registered: 2-2001
| | Posted on Saturday, June 15, 2002 - 6:49 pm: | |
On York compressors there are variations as to the position of the two outlet ports. It is possible that the two are reversed and you are compressing into the low side. In other words some Yorks high side is the left port and some are on the right. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 4
Registered: 5-2002
| | Posted on Saturday, June 15, 2002 - 4:16 pm: | |
forgot to mention, the guy at the a/c shop mentioned
that normally the system will take at least 2/3 of
the full charge without the compressor running.
my car only accepts about 1/4 of the full charge
without the compressor. this could point to a
problem with the schrader valve on the low side?
I have another compressor with fittings from
a 308. we can try swapping the fittings it there is a logical reason why it would matter. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 3
Registered: 5-2002
| | Posted on Saturday, June 15, 2002 - 4:08 pm: | |
hi all,
wrt the compressor turning, there is no real choice.
the thing only can mount in the car one way.
the second compressor is the york from napa. the first is probably a york from GT (I didn't order that one). both are probably rebuilt.
the drier was replaced on the first round. I think the system would take around .25kg quickly, then it took over 100 psi of pressure to cram up to .45kg or so into the low side (full charge is 1kg).
unless I have the theory completely wrong, the only way the high and low side can be the same is
if the compressor/clutch is bad, or whatever is at the other end converting high->low is open...which I assume is the expansion valve. all these parts have been replaced.
if the condensor for some reason doesn't work, then
I don't know what happens if the freon stays as
a gas all the time, and likewise I don't know what happens if the drier is not doing whatever it does besides removing moisture.
is there some way to test the compressor by disconnecting a line and putting a gauge or something on the end...or test a compressor on
the bench?
|
Aaron Marks (Aaronb)
Junior Member
Username: Aaronb
Post Number: 56
Registered: 1-2002
| | Posted on Saturday, June 15, 2002 - 9:43 am: | |
Don't be so sure about getting 2 bad compressors. I had 2 bad ABS pumps in a row - 3rd one was the charm. (guess that's what we get for buying used parts without guarantees.) |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1466
Registered: 2-2001
| | Posted on Saturday, June 15, 2002 - 5:24 am: | |
Did you replace the drier? How much freon goes into the system when trying to charge it. |
David Feinberg (Fastradio2)
Junior Member
Username: Fastradio2
Post Number: 53
Registered: 4-2002
| | Posted on Friday, June 14, 2002 - 10:13 pm: | |
Phil,
I hate to be overly simplistic, but...
Is the compressor turning the "correct" way?
Designed to spin CCW, but spinning CW on the car?
Just a thought...
David |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 2
Registered: 5-2002
| | Posted on Friday, June 14, 2002 - 10:07 pm: | |
hi all,
here's the blow-by-blow:
<ul>
<li> a/c never worked really well
<li> high side line blew due to the hose rubbing against a sharp piece of the frame where it loops
up over the gas tank (the self-disintegrating foam that ferrari wrapped around the hose to pad it was somewhat less that effective...next time you are in there, you may want to check your car. The high pressure hose is the smaller one with the bent metal fitting at the top of the compressor).
<li> replaced the line (that was fun :-)), receiver/dryer, and just for grins the compressor
<li> after closing the system and evacuating, the
r12 just didn't want to suck into the system
<li> replaced the clutch even though it appeared
to be ok with a used clutch from GT. same problem.
<li> replaced the expansion valve
<li> took it to a/c shop to get charged. same problem. The high and low side gauges read
around 100psi each, which is probably the pressure that the charging system was applying.
<li> assumed the new compressor must be bad, so
replaced it again. back to the a/c shop...same
problem.
</ul>
<p>
When changing the expansion valve, I disconnected
the lines at the compressor and ran compressed
air through both. The air came out at the expansion valve hose ends as expected.
<p>
So I'm baffled. The compressor appears to
be turning when the clutch engages, but the
high and low side pressures stay roughly the
same. If the pressure on the low side is
cranked up, the high side slowly rises to
equalize. The only thing left unchanged is
the condensor, evaporator, and the two fittings
on top of the compressor.
<p>
Any ideas on what the problem could be or what tests can be done to isolate? I seems a little
unlikely that I got two new compressors that were bad. Oh yeah, when I had one of the compressors
on the bench and spun the shaft, the discharge side was producing pressure.
<p>
Thanks, phil |
|