A/C questions--please help!

Someone please help me with air conditioning questions. I live in Seattle, so I am relatively unfamiliar with how to maintain it. I have done a fair amount of looking around on the internet, but haven’t found much regarding my specific questions. Here’s the back-story:

The car is an ’87 Mondial with a Sanden 508 compressor. I have had the car for about 8 years, and it has never been serviced in the time since I couldn’t find a shop that would work on the R-12 system. I believe it had been recharged shortly before I bought the car, because one of the hoses was damaged so it was replaced and the system recharged.

The A/C has always worked, although right before the recent incident I wasn’t sure if it was cooling very much. For the last year or so there has been a sound that I thought was a loose bolt coming from-it turns out-where the compressor is located. I only noticed it when the top was up, and I don’t recall it making a difference whether or not the a/c was on or not, including defrost.

Coming back from a 2-hour drive there was a sudden thwack of a belt breaking and the noise ceased. I identified it as the a/c belt and flat bedded the car home since I couldn’t exactly remember the belt arrangement and was concerned chunks might have gotten into the timing belt area. I’m not entirely sure the A/C was on when it broke, although I was switching back and forth between heat and defrost so it could have been.

It was time to change the timing belts anyway, so now I’ve got it apart and want to address the A/C while I’m in there. It can be removed while still connected, so it’s sitting there under the car.

Here is some information:
1. The head of the unit turns freely with very little resistance. I think we can safely say it’s OK
2. The compressor side turns, although with more effort. It turns smoothly, so I don’t think anything inside is broken. That doesn’t mean it didn’t score up the piston walls or fill the rest of the system with metal shavings. It almost feels OK, like adding lubricant would make it right again. It did drag enough to break the belt though, I assume.
3. The belts aren’t off yet so I could start the car to run it for testing, although I’d rather not re-install the compressor unless there’s a pretty good reason—like someone telling me the compressor is probably fine. See question 2 below.

My questions:
1. Is there any way to tell if the system is charged—i.e. can I disconnect the compressor without releasing R-12 and getting a lecture from a technician?
2. Any chance that the compressor would work acceptably with lubrication? Either recharge with R-12 that I now see on eBay or go to R-134.
3. I believe I can get a replacement compressor designed for R-134 and intended for installation in 328s. I would expect that it would be a bolt in, any reason why not?
4. Can I install a new compressor and safely drive it to a shop to have the system flushed, or should I have a mobile company come and flush it without the system connected which would allow work on the car without tons of disassembly due to the poor accessibility of the compressor, although if anything had to be done with the engine running it would require either a second visit or charging it then taking it to a shop for final completion.
5. When installed the oil fill port is not on the side as I think they are supposed to be, it is quite low on the side of the compressor. Is that correct? I don’t think the bracket can be installed differently but it seems odd to me.
6. What am I not thinking of?

Thanks so much for any responses.

 

Heya mate,

The only way to tell if the system is full of charge is to place a manifold gauge set onto the system and this will tell you if there is pressure in the system.

The compressor would be the original one for sure. While the engine is out for the cam belt, I would replace the compressor with a new one. Change all the orings and fit a new drier and re-charge with R134A.

Hopefully there isn't any metal in the system. But once you recover the refrigerant (or dump it), you will soon see if there is any metal or a metal-like paste in the system. That will tell you if there was a failure with the a/c compressor.

I just replaced my compressor last year in my 348. It was the original Sanden one also and was 24 years old. The clutch burnt out and the front seal was leaking also which is why I replaced it.

When I removed it, the oil in it was brown like chocolate. Again, the original oil. I flushed out the a/c lines and fit a new compressor, dye and receiver drier.

Can't comment on that sorry mate. You should be able to find a direct replacement compressor for you car. The compressor will work with R12 or R134A. You just need to make sure it has the correct oil in it for whichever refrigerant it is that you are going to use.

You can definitely fit a new compressor to the car and drive it to the shop to have the hose flushed if required.

If someone can come over and flush the hoses at your place, then even better. But again, that's if there was a failure.

If there was no failure and then there is no need to flush the hoses. The left over oil in the hoses is not enough to cause an issue if you intend to use R134A refrigerant and the PAG oil that goes with it.

That is perfectly ok where that oil filler hose sits. The oil will always sit level in the compressor.

Nothing.

It's all good, as long as there was not a failure in the system then it's easy.

I would fit a new compressor and change as many o-rings as you can find. The ones on the evaporator in the front trunk area might be a little tricky, but don't stress too much about them.

You can still use R134A with those original o-rings. It's just good practice to replace the o-rings on the components that you replace.

But if they are 20+ years old, probably best to change the ones that you can access and leave the ones that are hard to get at alone.

After the compressor has been fitted, fit a new receiver drier. But do not connect it into the system until you are ready to have the system vacced down as opening that drier to a system that is not ready for vac can ruin it as it fills it full of moisture and can ruin the dessicant balls in the drier.

So fit new compressor, orings and drier. Have it vacced and charged by a workshop if you don't have the ability or tools to do it at home.

Hope this reply helps a little and if you need to know anything else please just ask.

I service and repair a/c systems on a near daily basis.

Cheers Pap

 

A couple of points, there is nothing special about the compressor, the Sanden unit I acquired for a very low price some years ago from Hodyon LP in Round Rock Texas. The clutch however is a Ferrari part (I think crosses to a tractor, but never settled that) and is very expensive. So retain your clutch if its good which it sounds like yours is, and replace the compressor. Add the new drier and o rings as the previous poster notes, and flush and charge with 134 and related oil and you are good to go. I also got some hose extenders that allow the low and high pressure ports to be accessible from the top of the engine bay. Got them on line and can't remember the source. Perhaps previous poster has a source? That way you can do pressure tests and such in the future with no fuss and effort.

 

My advice would be to stay with R12. It's well worth the effort if you care about the efficiency of your A/C. If you do choose to go the 134a route I suggest you do your own research. Many shops do not know how to correctly downgrade to that refrigerant. My 348 was converted by a very well respected shop and yet they still used
PAG oil instead of ester oil. That means lots of flushing for me when I take it back to the R12 it was designed for.

 

Thanks Mike, I should have made mention that you can still use PAG oil in the R12 system, but you cannot use Ester oil in the R134A system.

Most compressors these days come filled with PAG oil as R134A is what the most common refrigerant used.

 

Pap-- to clarify, PAG oil is typically the factory lubricant in 134a systems, but it cannot tolerate even small amounts of R12. Ester oil is compatible with both refrigerants, making it a better choice for conversions. The original lubricant in the OP's system (and ours as well) was almost certainly mineral oil.

I'm not looking forward to flushing the PAG oil out of my 348 when I restore the system to the more efficient R12. Wish they'd used ester oil in the conversion...

In general it is better to stay with the original refrigerant for maximum effectiveness. It gets very hot and humid where I live, so going back to R12 is worth the effort. The OP is fortunate if system is still on R12, although he will have to seek out someone willing and licensed to work on R12 systems.

 

Cheers Mike.

 

Thanks all--a very useful discussion for me. I'll check in with the place that repaired the hoses previously and see if they will touch it with R-12. Otherwise it may be R-134. As a note, the compressor I looked at is a 7 piston, so apparently better with a less efficient refrigerant like R-134. Who knows, I might get through this by the end of the summer--I work on it about 15 minutes a night with my 8-year old. Not efficient, but the only way I can pull away to do it (it's family time!) and he's actually getting fairly helpful.
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Does anyone know where the "go to" place is in the Seattle area for working on Ferrari AC units?

 

I'm going to throw a monkey on this and you'll have to decide if it's worth the hassle or not.

My understanding is that the old R12 hoses are not compatible with R134A due to the smaller sizes of the R134A molecule. In other words, aside from insufficient cooling (conversion from R12 to R134A), you'll have leakage of the refrigerant on the hoses.

I'm no A/C expert, so accept this with a grain of salt.

 

Here's an update for your consideration, and of course I hope for some of your recommendations.

Some internet research suggested that one can see if the system has pressure in it by pressing on one of the valves, and sure enough it sprayed a beige froth all over my arm when I did that. This proves that it has at least some pressure and the oil (which the froth settled into) isn't actually all that dirty. At least it isn't brown sludge, sort of dirty yellow.

I also found a Sanden service guide that recommended putting a socket on the end of the shaft to see if it turns smoothly, which it does--no tough spots or jerks. I think the compressor is OK. As noted earlier, the head spins freely.

This leaves me with two questions:

1. Do I just recharge it with R-12 and install a new dryer? I finally found a place that will do it although I have no idea what it would cost and how long it would last. I don't think they have any competition so they can charge whatever they want. Or do I just get it all flushed, change the O-rings etc and go to R-134. There's a pretty strong sense I get that people like R-12 better, but honestly it feels like I should just bite the bullet and go to R-134 since the R-12 may not be around for another recharge.

2. What was making the loose bolt noise? Either it is something in the compressor (except that it feels OK) or would the belt make that noise if it were too loose? I'd expect the classic belt squeal, not a vibration. I would also expect that if the compressor were the source of the noise I would feel it somehow. Thoughts? Could the clutch be not engaging properly and making the noise?

Thanks so much for the feedback.

 

As a further note, I spoke with the shop that did the work on my car previously. There was this 90-year old guy that had his own equipment that would come in and do the R-12 work, but that was about 9 years ago and he's no longer wrenching. They will convert the car to R-134, but only if the system is already evacuated.

 

I'll cast another vote to stay with R-12.
It's more efficient. And -- after they told everyone to convert, they suddenly "found" that R134 isn't good for the "ozone" either.
(There was talk of trying propane as a refrigerant.)
R-12 isn't inherently toxic, like R-134.

The pulley will turn freely if the electromagnetic clutch is disengaged.
On my 328 (same vintage), I was told to turn on the key and then turn on the AC without the engine running, to hear if the clutch engaged.
If not, there's an issue with the thermostat, or with the high or low pressure safety switches.

If it engages, and you still have no cooling, you may have a leak.

R-12 got a bad rap in the '50s, because it's a slippery molecule, and early systems leaked.
But I sold an '88 Celica GT-Four in 2003 with the original R-12 still in it.
The new systems only leak if damaged.

Another issue on the 328 series engine would be getting the mounts right, to align the pulleys.
They had to replace the alternator mount twice before mine stopped eating belts.

 

I had a R-12 system on a beater car and filled it with R-134 from one of those DYI kits they sell at Pep Boys. Guess what, it worked great! Dont ever do this hahahah. I just wanted to see if the compressor and associated electronics were working and they were. I then took it to a shop who drained out my bad R12/R134 mixture, flushed the system and refilled with R134. Besides locating the fill port schrader valve and giving it a quick push, you can find the little window by the dryer and look if you see fluid. Most cars these days have a UV dye added for leak detection.

Sounds like you had a bad belt and or tensioner.

The shop should pull your R-12, change the dryer, fit a new belt, flush, recharge with UV dye and recharge with R-12. Hopefully the compressor is still good and you should be on your way for $500. My TR was a little low on R-12 when I bought it and I found an old school AC guy who did exactly this. I dont know if a compressor change is an engine out thing on the Mondial, but the compressor will be in the $400 range if you dont go to Ferrari. Probably less if you get a rebuilt unit. As for the noise, if the belt was old enough to snap, im gonna go with it being the cause of the noise. But you have to get it to a certain point in order to further diagnose. AC systems historically are cheap to work on but the R-12 will set you back $50-100 a pound due to it becoming harder to find and EPA regulations etc. Thats why the pull your R-12 and save it.

Again for the folks with pitchforks, I did the DYI PepBOY on my beater car thing once for about 4 minutes to see if the system was working as a quick diagnostic before I took it to a pro.

 

Peter, the fact that the compressor shaft rotates is no assurance that the internals are good, but it's reason to have hope. As others have suggested, I'd look at the tensioner and mounting hardware to see if there's a problem with any of those. Once you're sure nothing is broken or seized, reinstall everything, fit a new belt, and see if the compressor runs. There's a decent chance it will, in which case nothing further needs to be done other than ensuring that the system is full of refrigerant. It's not uncommon for AC systems to lose refrigerant over the years through osmosis and seepage past the Schrader valves, so it's likely that yours will need a small shot of gas in order to return it to peak effectiveness... if Ferrari air conditioners can ever be called effective.

BTW, it's easy to tell if the system is low on refrigerant-- if there are tiny bubbles swirling in the sight glass on top of the dryer when the compressor is engaged, it needs gas.

 

Evacuate it. Change the dryer and charge with r12a and compatible oil.

 

If you look in the top of the right hand side of the engine you will see 2 connection points on the pipes coming from the compressor, these have plastic dust caps on them. Connecting a fridge gauge set to these will tell you if system still has gas. With the ignition on, switch the ac on and you should hear and see the clutch engaging the ac compressor. If it does not then go into the bonnet compartment and you will see a pressure switch mounted on top of the drier-pull the connectors off and see if the clutch engages, or you short them together- this protects the compressor from operating with insufficient gas in the system. Assuming the system still has gas in it, you will find that the compressor will have resistance to turn as it is subject to positive suction pressure and when the compressor has been stopped for a while the suction and discharge pressue will equalise, this could be 60 to 80 psi so dont expect the compressor to be free. In Europe it is illegal to use R12 and it is not available, you can get what is called drop in equilivants like RS 24 which i used in my mondial with no mods to hoses etc. I was surprised to hear R12 being talked about as i assumed it had a world wide ban. Any ac company will just evacuate it to be distroyed.
If the system is pumped down and holds vaccum then the compressor is probably ok, so i would hold off fitting a new one as you dont want scrap from a failure in a new one
In regard to the oil in the compressor, this flows around the system with the gas and if you have not loss the gas then you still have the oil, unless you can see oil leakage around the compressor shaft seal-if the compressor is damaged badly it might make the shaft mechanical seal leak, so you will see oil by the clutch as the gas blows out bringing the oil with it. You need to get a gauge on the pipes to see if still pressure in system. When it is running put your hand on both sides of the drier, should be no difference in temperature, if it is colder after drier then it is getting dirty and the liquid is expanding over it. You get this chilling effect over the expansion valve which is how it should work but a dirty drier slows the refridgerant flow, partly expands the liquid to gas before it gets to the expansion valve and this decreases the refridgerant effect in the evaporator- hence the ac is having a job giving the cooling effect

 

The oil must be compatible with coolant. Another benefit staying with r12a.

 

Be very careful when working with the A/C system.

The refrigerant will permanently blind you if sprayed in the eyes.

Make sure you (and your 8 year old) wear eye protection.

Sid

 

Thanks for all the responses. I had no idea about the risk from the refrigerant. Thanks so much. I hope to not touch it again (and waste the precious stuff and/or blind us.

Over the weekend we tested the clutch, which seems to engage just fine when the a/c is switched on (engine off) At least that works, and does that indicate that there is adequate pressure in the system to keep the low-pressure switch from preventing operation?

I believe at this point that I will finish up the belts and re-install it. Everything tested seems OK although I still haven't identified the source of the noise. If it wasn't the belt, then.....I'll have to see if it goes away after flushing the system. Or is it likely that it is the internal helical drive gears? I hope that shop could feel that or see a lot of shavings during the flush.

For reference if anyone is looking at this in the future, my connection points may not be the same as mike32's, as they are on the angles where the lines come out of the compressor. I am afraid they may be very hard to reach once it is back in, but it must be possible somehow--probably through the wheel opening since they are under the compressor.

Thanks for all the help!

Any further tests anyone can think of, or do I proceed to put it back together?

 

If you can see the hose connection points you can connect to them via the top of the engine bay, mine might be a right hand drive but it not going to be different- you do need long arms but these are knurled screw on connectors after you get the dust caps off. Only other thing i can think off re the compressor is the way the clutch is attached to the imput shaft, is it possable it has come loose or chewed a key up. Check the clearence behind the clutch to the compressor body in case something has become lodged and jammed the compressor. Having a bang and the belt snap indicates a rapid stop either externally or internal disaster. Only other thing that could have given compressor a shock is liquid refridgerant coming back up the suction line from the evaporator- like injecting water into a car air intake. Rapid hydraulic effect but very unusual with ac system

 

My advice: Given that the compressor turns freely, and there is still R-12 in the system, and you only had a belt break, then replace the belt. That's it. That is all you need to do. You're system is probably low on freon, because they all leak over time (new ones leak much slower than old ones, but they all leak.) If it does not cool as well as it used to, then have someone top it up. R-12 is still available and legal to use, even though it has not been manufactured in or imported to the US for quite a while (unless your greenie state has banned it.) Don't change to R-134a unless you have to.

Your compressor engages when you select defrost in order to remove humidity from inside the car. That is why it engaged when it did.

 

If you are hearing a lose bolt rattle noise when the compressor is running... there are a couple of possible reasons. Sanden style compressors have a spinning wobble plate that drives some pistons that are pumping the refrigerant. A loose bolt noise normally means that one of the piston rods has broken. Most Sanden style compressors have 5 or 7 pistons that are about an inch in diameter. You may not get knocking until it is spinning fast enough for the broken rod to be rattling around enough to hear it. it is possible that it will finally jam and lock up... . thats where you can get broken belts from as well. it spins fine... then locks up and snaps the belt. And it can free up again if that part frees up and unjams.

in the the end.... rattle noise... Bad.

depending on how the compressor broke you could have sent bits of metal through the system. Those bits can block the throttle expansion valve or go all the way around to ruin a new compressor. If you fail a compressor.... always replace the condenser and receiver/dryer as there is no way to fully flush them out and then fully flush the evaporator and lines with the expansion valve disconnected.

if you want to see what the inside of a compressor looks like... this is a good youtube video

https://www.youtube.com/watch?v=o-DBEYJhFLg

 

Yes, because, for engine bay packaging reasons, the compressors on our V8 Ferrari's are mounted reversed compared to regular cars, they turn CCW. The Sanden SD507 (308 variety) and SD508 (Mondial) are able to operate CW and CCW because they use a straight cut bevel gear drive.

The plug'n'play Sanden R134a replacement compressor for the SD508 is called SD5H14. It (and all new 7 piston Sanden compressors) uses non-straight cut gear seats to reduce operating noise. They can only operate CW (correct for normal mounting direction of most cars), as with CCW operation, the gear set pushes itself apart leading to noise at first and then internal self destruction of the compressor.

As for the Chinese made Sanden copies: I don't know whether they were patterned on the SD508 or the SD5H14...

The compressor is angled about 30° to the front, and so is the filler; see drawing:
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I would suggest you open up your SD508 and check where the noise came from. It might be a broken valve plate, which is readily available and easy to replace. You can then flush the system, change the dryer (which you should do anyway), refill with Sanden SP-20 oil and R134a. Just in case you go that way, here some information for the change:
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