| Author |
Message |
Kelly (Tifosi1)
Member
Username: Tifosi1
Post Number: 351
Registered: 2-2002
| | Posted on Saturday, August 17, 2002 - 9:37 pm: | |
Update,
I've now put in two cans this week. I still get 25 to 15lbs on the low side. On low fan I get 45 degrees at the vent.
During today's drive I get 50 to 55 at 90 degrees out side.
I think I need another half a can.
I also think I may have a slow leak. I got a free loaner tool from AutoZone. It has the tool dye and black light for leaks. $90 Deposit
I should get to it this week.
I'm also going to let you know what the high side pressure is. If the low side alsways stay between 15 and 25 maybe I can judge how much is in the system via the high side.
I'm trying to find a way to fine tune the system.
Thanks for everynones' help
Kelly |
Steve (Steve)
Junior Member
Username: Steve
Post Number: 193
Registered: 2-2001
| | Posted on Friday, August 16, 2002 - 9:05 am: | |
Ed you hit it on the head. When I click on the compressor it takes 200-300 rpm's off the engine. So I just cranked up the idle. I was thinking though I recall back in the early days of AC on most American cars they used to have a throttle solenoid that turned on with the compressor.It just became another throttle stop at a higher rpm. I wonder if I can set something like this up.
Kelly why don't you pick up a cheap gage at an auto outlet and check the system If you are getting 50 degree air out of the ducts something is wrong. I usually get 40 -45 degrees and 35psi on the low pressure gage. Keep trying you'll get it. |
Frank Foster (Sparta49)
Junior Member
Username: Sparta49
Post Number: 52
Registered: 3-2001
| | Posted on Friday, August 16, 2002 - 8:35 am: | |
Kelly, I noticed the engine running rough also when the compressor kicked on. It actually killed twice. I just turned the idle adjustment screw a couple of times. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1809
Registered: 2-2001
| | Posted on Friday, August 16, 2002 - 8:11 am: | |
You may need to increase the idle RPMs during the summer months when the A/C is in use since most Ferraris do not have any sort of idle compensation device. |
Kelly (Tifosi1)
Member
Username: Tifosi1
Post Number: 349
Registered: 2-2002
| | Posted on Friday, August 16, 2002 - 7:34 am: | |
Update,
Well I put in whole can last night. With the fan on low it went down to 50 degrees at the top vent.
Problem was, I put my pressure gauge on after the can was finished. It showed 10PSI on the low side. Started the car up, turned on the air. 10PSI I think the gauge is broke.
I'm going to pickup a new gauge today and try again tonight.
I will point our on more thing I notice, when the compressor was on, it seemed that the engine was running ruff. Turn it off fine, turn it back on ruff again. I really think I will never get it below 60 ot 50 degrees at the vent again. I think the compressor is about had it. We'll see.
Thanks
For all your help.
Kelly |
Bruno (Originalsinner)
Member
Username: Originalsinner
Post Number: 417
Registered: 5-2002
| | Posted on Thursday, August 15, 2002 - 10:40 am: | |
15 is low. |
Kelly (Tifosi1)
Member
Username: Tifosi1
Post Number: 348
Registered: 2-2002
| | Posted on Wednesday, August 14, 2002 - 8:32 pm: | |
Ok I just ran a test.
Systems pressure 85 PSI,
Idle 25 LBS, vent with fan on 3 58 Degrees.
2-3000 RPM, could not tell much cause I was pulling the throutle cable, low side drops to 15 LBS. That's a 10 LBS loss. But, it ran steady at 15 LBS.
Still 58 Degrees at the vent.
I'm going to pick up some more 134A tomorrow and try a half a can.
It's easy to tell down here what's left in the can with thie humitity
Thanks for the input ED.
I've help a couple of guys with this, they are all calling me saying they are getting 40 degrees at the vent. needless to say the ribbing is getting pretty bad.
Kelly |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1789
Registered: 2-2001
| | Posted on Wednesday, August 14, 2002 - 7:37 pm: | |
My experience has shown that the ideal low side pressure is 25-30 lbs on the low side with the blower on low speed and the rpms at around 2000. The High side should not be over 200. If you increase the blower speed you will notice that the pressures increase and the outlet air temperature will rise. If the low side pressures go much lower that 25 lbs you will need to adjust the temperature switch to allow the compressor to cycle as you are approaching freeze up of the evaporator. Outlet air temperature should not be lower than 40 degrees as freeze up is approaching. |
Kelly (Tifosi1)
Member
Username: Tifosi1
Post Number: 347
Registered: 2-2002
| | Posted on Wednesday, August 14, 2002 - 7:24 pm: | |
Ok,
This is what I'm hearing and what I would like to add.
According to the chart, at 85 degrees I should be between 95 and 100 PSI of pressure.
Low side according to Steve should be 25 to 45
PSI.
With Verell and the website he posted, Thanks a lot, It should be 12-15 PSI.
In my car the charge right now is at 85PSI with nothing on and the car not being touch for a couple of days. This is after me adding some 134a.
Before I added the 134A I noticed on the low side at idle I was at 25PSI, when I reved the engine up to 3500 or 4000, the Pressure dropped to 12 or 15 PSI. I did this after a trip where we ran at 50 degrees, sometimes 40, the whole time and towards the end of the trip it went to 60 degrees at the vent.
Several of my freinds who have been doing this for years said that when you see a drop like 10 PSI when you rev the engine you don't have enough in it.
I think, I'm going to bleed it down till I get the 12-15 low side presseure, cause I can always add it back with a can of 134a.
But, I doubt if it will work because if I bleed it that low, I think it will go to vacum, becasue there's not enough.
Thanks for everyone's help. I'll let you know how I make out.
Kelly
|
Steve (Steve)
Junior Member
Username: Steve
Post Number: 189
Registered: 2-2001
| | Posted on Wednesday, August 14, 2002 - 7:21 pm: | |
The vintageair site kind of describes how I do the process but the 6-15 PSI low side is contridicted by the information printed on the 134A cans being sold at auto outlets. So it makes you think what is the correct range.The stuff I buy says stay in the 25-45 psi range and your good.I guess this will be a question with out an answer. Nice research here though. |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 253
Registered: 5-2001
| | Posted on Wednesday, August 14, 2002 - 5:21 pm: | |
FOUND R134a PRESSURE GUIDELINES:
I finally found the R134a pressures I was looking for:
High side pressure: 2.15 to 2.2 x ambient temp (160-250 psi depending on temp.)
Low side pressure: 12-15 psi
Duct temperature: 36-46 degrees F
(Steve,
It's hard to argue with emperical results. However, based on the above, at 25-45 psi low side, you may have been slightly over-filling the systems. Probably not enough to cause any adverse effects, and maybe just enough to ensure an extra year before needing a recharge.)
In the process of researching, I've come up with some very useful Auto A/C web sites:
http://www.aircondition.com/ - A wealth of info including a chat system for Q&Q. Not as easy to use/search as the F*chat tho(sigh). Lots of good discussions/pointers.
http://www.vintageair.com/vintage.htm - A/C products for highly customized or vintage cars.
They have an excellent A/C troubleshooting guide that gave the pressure info I've been looking for:
http://www.vintageair.com/download/Trouble.doc
http://www.ccicompressor.com/ - The York style compressor used on most 308s is still in production by Climate Control Inc. CCI is selling them for Truck & Marine applications. I suspect they may be making the NAPA units mentioned elsewhere in the chat.
CCI provides an excellent York style compressor repair manual:
http://www.ccicompressor.com/SrvcManl.htm
http://www.rparts.com/ - A/C parts including York style CCI compressors & parts including an R134a compatible crankshaft seal kit, part # 010-0603--$14.95"
|
Steve (Steve)
Junior Member
Username: Steve
Post Number: 188
Registered: 2-2001
| | Posted on Wednesday, August 14, 2002 - 3:43 pm: | |
Verell you pretty much detailed the procedure from the course. My personal opinion is it is overkill but that's my thoughts.When I did the conversions I used the short cut method. After pump down and leak test then start the fill process. Fill up should be about 80% of R12 volume. Using a vent therm. start the car and run at 1500 RPM with AC system on full with city setting. Short out pressure switch on R/D to engage clutch. Check R/D sight glass and temp at ducts. By the way the temp. in the garage was around 80 degrees. When duct outlet temp. is between 35-45 degrees stop the fill process. BTW when I looked at how much 134 I put in it came out to be between 75-85% of the R12 requirement. Check low pressure gage and see if it is in the 25-45 psi range ( I usually shoot for mid range).Button everything up and drive it home. I've done this with 8 cars so far (Ferrari's,Jags,Volvo's ,Honda,etc.) and they all still blow cold . I don't claim this to be the ideal process but it works for me. By the way I have 20LBS. of R12 left is anyone looking? |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 252
Registered: 5-2001
| | Posted on Wednesday, August 14, 2002 - 9:05 am: | |
Steve,
The system still has enough R134a to deliver an outlet air temp that is ~25 degress below outside temp.
I understand that R134a is much more finicky than R12. A few ounces too much or too little will put your outlet 10-15 degrees higher than optimal.
AC101:
My understanding of the general procedure for getting an optimal fill using any refrigerant is:
1. Hook up gauges to refrigerant container, compressor inlet & outlets, purgeing the gauge lines in the process.
2. Place a large fan in front of the radiator w/ a temp probe measuring the ambient temperature(ie the temp. of the air being blown by the fan).
NOTE: In the case of the 308, the system must already be warm enough for the radiator fans to be running.
3. Start the engine & run it at the RPMs corresponding to ~40 MPH.
4. Check the high & low side pressures against the recommended pressures for the ambient temperature.
5. If the high side pressure is low, and the low side pressure is at or below the recommended pressure, then add refrigerant until the high side pressure is at the recommended value.
If either the high or low side pressure is too high at any point, then there's likely a problem with the sytem that must be fixed.
NEED HIGH/LOW SIDE PRESSURE VS TEMP FOR R134a:
What I don't have is a chart or formula for the optimum high & low side pressures vs temp. for R134a.
IS THIS HOW TO USE STATIC PRESSURE?:
I'm under the impression that the static pressure chart can only be used when the entire system's temp is stabilized at ambient.
BTW, here's the locaton of a R12/R134a static chart:
http://www.aircondition.com/dsmobileac/static.html
If the static pressure is below the chart pressure for the ambient temp, then there's no liquid refrigerant in the system & the system definitely needs topping off.
If the static pressure is above the chart pressure, then the system is over-filled.
I also understand that the static pressure is only a gross indication. ie: It only tells you that you're in the ball park.
Thus using the single gauge /static pressure approach is 'plugNpray'.You need to use gauges with the system running to determine if you've got an optimum charge.
Do I have the above pretty much correct?
|
Kelly J. Vince (Tifosi1)
Member
Username: Tifosi1
Post Number: 343
Registered: 2-2002
| | Posted on Tuesday, August 13, 2002 - 8:42 pm: | |
Steve,
Is the pressure you are talking about at idle or at what RPM and temp.
I got a temp chart, been having a hard time reading it. From what I gather, if the outside temp is around 85 then without the car running, the normalized pressure of the system should be 95 to 100 PSI.
ANY Advise?
Thanks
Kelly |
Steve (Steve)
Junior Member
Username: Steve
Post Number: 187
Registered: 2-2001
| | Posted on Tuesday, August 13, 2002 - 7:46 pm: | |
Verell all you need to do is go to a NAPA or other auto parts chain and get their single gage and plug it into the low pressure side and fill it up to between 25-45 PSI.You might want to add a can of "cold shot" which adds to the efficency of the 134 . Do I assume that your system still has some 134 in it? If not maybe you should pump it down and seeif you have any major leaks. If its OK I would just buy a couple of cans of 134 and fill it up. |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 251
Registered: 5-2001
| | Posted on Tuesday, August 13, 2002 - 7:38 pm: | |
I need to top off my system w/R134a. What should the high & low side gauge pressures be when the system is properly charged w/R134a?
Best I've been able to come up with is that the high side pressure should be ~2.2 to 2.3 times ambient temp, and that the low side pressure will be 'lower than with R-12'.
I've got gauges, & have done R-12 recharges for years. I also have an R134a pressure vs temp. chart.
BACKGROUND:
My A/C was converted to R134a when I bought the car 3 years ago. It initially worked fine, but has slowly lost chilling capacity until today it barely blows 70 degree air at 95 degrees outside.
Since we're in for at least a week of 90+ weather, I've decided it's time to top off the system. |