A/C gurus... got a simple question

[Scuba Steve]

I want to replace the o-rings at the condensor, compressor and drier on my 924S (same as early A/C system?) but I don't know which and how many o-rings to get. And does the new drier include necessary o-rings?

I'm pretty sure it's one of the o-rings up front at the condensor that went out because of the old gunk buildup on one of the fittings. And now the system doesn't have enough charge to run the a/c anymore while the low pressure switch / clutch check out ok per Clark's Garage. I also plan on ordering a drier and have a friend with the right equipment to pull a vacuum, and then 134a is going in after I drain the compressor of old oil.

Thanks in advance!

[Zero10]

Some advice:
1) Don't fill it with R134a, even when properly converted you will be disappointed
2) Change all the O-rings you can reach. Best bet is to have 2 cars, take all the O-rings out and drive another car to the parts store to match them up. Replace them all and make sure to tighten the fittings properly (i.e. they are easy to over-tighten and crush the O-rings).
3) The new drier _should_ come with O-rings, but they don't all. If you are ordering from somewhere it is in stock, have them check.
4) Use an R12 substitute (freeze 12, duracool, red tek, etc.). It will out-perform even the original R12 in the system.
5) Last but not least, know when to stop charging. Most of the A/C systems I look at are over-charged.

Don't go entirely by gunk build-up to find the leak, change the visible O-rings, everywhere you suspect the leak is, and partially charge the system. Put 10-15psi in it and let it sit for an hour. Then go around with a sniffer and see if you can find any leaks. Better to fix them now before you fully charge the system.

[Scuba Steve]

I refilled with Duracool on top of what little R-12 was left last year. Results were ok... I think there may have been moisture in the system because it'd been an unknown number of years since the system had been serviced, and who knows who did it. At ~30psi it would still cycle. Actually I probably will refill with Duracool because they sent an additional two cans 6 months after I ordered for some reason. Forgot about those... I'll need to fill the compressor with oil and would prefer the newer kind. How much does it take?

I had actually hoped to order the o-rings at pelican along with a bunch of other parts I need. May just order the drier, see what it comes with and find a shop here for the rest. Another thing I wanted to do is to swap out the R-12 fitting on the low side (on the compressor itself) and replace it with a 134a one. Is that possible? Adapters that sit on top of the fitting don't work well on early cars / 924S because that part of the compressor is close to the engine.

[John_AZ]

When I replaced o-rings, the tech advised to rub first with AC compressor oil to prevent a dry pinch failure. Are you sure your loss of charge is not due to a leak in the compressor shaft to front seal? Your 924S compressor shaft may have developed a grove.

John_AZ
1988 924S
1987 924S

[Scuba Steve]

I checked after reading this - there aren't any signs of leakage on the compressor. The area looks clean and dry. I guess process of elimination could turn up a problem there if it leaks after changing the o-rings. The only solution for that problem is to replace the entire compressor?

[Wipeout]

How difficult is duracool to use, guys? I have R12 that's not blowing very cold any longer (probably on the last legs of the original 22-year old coolant, just like the gasket I replaced this weekend...grrrrr).

[Scuba Steve]

I'll be able to give you a report soon... the drier came in the mail today and this weekend I may be able to take the system apart to get the o-rings I need. I also want to change the fitting on the compressor to the newer 134a style. You will need to do this or get an adaptor because duracool cans come with 134a fittings. Adaptors don't work well on early cars because there's not enough room with the R-12 fitting + adaptor for the hose to fit without hitting a support for the engine. Makes charging the system extra fun.

Then next week I can borrow a vacuum pump from a coworker, get the compressor oil right, add a little flourescent dye, put it all together and see what happens! On your system if it's low, then it's low for a reason. My system was like yours last year and I added some coolant. It stuck around for a few months but it's gone now.

[mattdavis11]

A 90 degree adapter and a 1 inch shorter belt works just fine, so does 134. What happened to the drier?

[Wipeout]

Interesting. I'll have to keep following the thread, then.

[Scuba Steve]

Originally posted by mattdavis11
A 90 degree adapter and a 1 inch shorter belt works just fine, so does 134. What happened to the drier?

I will be opening the system to replace the o-rings, so I need a new drier.

I would also like to replace the whole r-12 fitting on the compressor to avoid shorter belt / adapter issues if possible. It looks like the fitting unscrews from the compressor. Can I go buy a 134a one to replace it with?

[mattdavis11]

Originally posted by Scuba Steve
I will be opening the system to replace the o-rings, so I need a new drier.

I would also like to replace the whole r-12 fitting on the compressor to avoid shorter belt / adapter issues if possible. It looks like the fitting unscrews from the compressor. Can I go buy a 134a one to replace it with?

What you are seeing is what i believe to be the threads for the r12 fitting, the fitting itself is not removable. I think. It's been awhile since I had mine off the car.

Anyway, when you opened the system, that did not constitute the need for a new drier. I still have my original drier, and I know it's a $20 part, why not change it, but it sounds like you've been lied to.

Ok, so the belt for our car is what a 40 1/2 inch five rib like this. http://www.napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=NBH&PartNumber=25050400&Description=Belt+-+A%2fC+%26+Alternator

Get one this one. http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=NBH&PartNumber=25050390&Description=Belt+-+Alternator

This makes charging so much easier, even if you stick with an r12 fitting.

When/if you get the 90 degree 134 fitting, remember to pull the valve stem out of the fitting on the compressor.

[ragreene801]

I have a somewhat unrelated AC question. My system appears to be leaking at the evaporator. The sniffer only registers when stuck into the interior vents. Everywhere I check under the hood is fine. My question involves the evaporator. The only one available form pelican is for later models. The one that otehr sites say is for mine ('83) can be found
http://replacement.***********************/parts/autopartswarehouse/wizard.jsp?year=1983&make=PO&model=944--001&category=All&part=A/C%20Evaporator&dp=false
and
http://catalog.drivewire.com/drivewire/baseline/quote-new.jsp?partner=drivewire&year=1983-1985&product=R1130-80243&application=290888&fm=1

Not that I am arguing that a part that usually costs $600+ is on sale for $35, but something just does not seem right. Some have mentioned that it is because there is no demand for early 944 evaporators. Both companies have confirmed that their price is correct.

Assuming the part is correct, how much should it cost to have it installed? If the sniffer is picking up freon at the interior vents, is the evporator the only possible culprit?

Thanks,
Aaln

[Zero10]

Unlikely that it is an evaporator failure.
More likely that it is an O-ring failure or an expansion valve problem.
My memory is not so good, but I don't recall how difficult it is to access on an early 944. It is relatively easy on the late cars, it sits directly under the blower motor and I have been told it is very easy to access with the blower motor removed. Maybe you are this fortunate?

Pull the blower motor, turn the A/C system on/off and work your sniffer around from that side.



As for changing the receiver/dryer, the problem is with R12/R134A. When there is moisture in the system it forms a rather powerful acid that eats compressor parts, O-rings, rubber hoses, etc.
So, if the dessicant in the receiver/dryer has been consumed you can do a whole lot of damage to your A/C system over time by filling and using it.

That said, with a hydrocarbon refrigerant the worst thing that will happen is the formation if ice crystals, and the consequent damages. Ice crystals aren't hard enough to damage the compressor on their own, but if they plug up the expansion valve it can be very bad. Typically you won't have that much moisture in the system, that is a bit of a worst-case scenario.

For that reason, it is a very good rule of thumb to change the receiver/dryer every time the system is left open. If you open it to change a fitting or an O-ring, don't worry but if it is open for a perlonged period of time it really should be changed.

Mine for example was open for 2 days while the compressor was removed. I have since filled the system to check for leaks, but I will re-evacuate it and change the dryer after I am satisfied there are no leaks.

[Razorback1980]

I agree, change the dryer...a 20 dollar part isn't worth the damage and your a/c system will not cool well.