Mr. Bones

My air conditioning ('86 LX, R-12) went almost overnight from cooling adequately to blowing hot air. The clutch was cycling on and off at about two second intervals. I found that the high side schrader valve was leaking so I took it in to get a new valve and have it evacuated and recharged. The shop put dye in so they could look for leaks in a few days. It was cooling good, and I took it back four days later. The mechanic said there was a small leak at the compressor front seal, but I might be good for the rest of the summer. About a week later, after not having run the AC for a couple of days, it started to blow hot again. (I don't mean heater hot, just outside air hot.) I took it back to the shop and they said the compressor was leaking at the seams and needed to be replaced.

If the compressor was leaking that bad why didn't the guy say so when he first checked it? Maybe the evaporator is leaking. They said they sprayed soapy water on the evaporator and observed the runoff under a black light, but when I bring it to have the compressor replaced they will check the evaporator with pressure. Having replaced the heater core I know that it's a huge job to replace the evaporator. I also know that there's no way they could have gotten to the evaporator with soapy water.

I looked at the system with a black light and I do see a small amount of dye on the seams of the compressor. As fast as it depressurized I would think that there would be a lot of dye. I pressed the schrader valve for a second and could see a lot of dye there.

My questions: Could the compressor be leaky enough to lose enough freon to make it blow hot in a few days and still not show much dye on the seal or seams? Could it still have enough freon but something else is causing the symptoms (hot air and clutch quick cycling)?

Thanks,

Mr. Bones

PRO50SC

In short, Yes

Mr. Bones

Do you mean yes, the compressor could be leaking that much without showing much dye, or yes, the problem could be something besides low refrigerant? Whichever it is (or both), could you provide some details about how and why.

Thanks,

Mr. Bones

PRO50SC

low on refrigerant causing the compressor to short cycle. Yes, the compressor could be leaking that much in a short period of time.
Another way to check the evap for leaks, it to get under the car and shine the ultra-violet light at the evaporator drain. If it's leaking, you should see stains around the drain opening.

Mr. Bones

Maybe I need to rephrase my questions. I know that low refrigerant could cause short cycling. My question was, can other problems cause short cycling? If so, what are they?

I know that the compressor could leak that fast. My question was, could it leak that fast and not show much dye? If so, how does the refrigerant leak out but not the dye?

My initial inspection of the evaporator drain didn't show any dye stains, but I haven't looked at it since the shop did their inspection. I will do that if it ever stops raining here.

Thanks,

Mr. Bones

PRO50SC

SilvrStang

I had a similar problem with my AC. It was cooling then it started blowing hot air. My friend came over and checked it and the compressor was completely gone. He said that theres six little cylinders that pump freon to push cold air through the vents (I dont know if i`m right but he said something similar to this) . I took it to this rebuildin shop and they rebuilt the whole compressor for 150 all ready to go. Its like brand new now. As far as freon goes be carefull if you try to flush it out yourself. Those things are like a bomb once u open the vents to get everything out and it smells horrible.

Mr. Bones

Regardless of whether there is any other leak, the compressor has to be replaced. It still has r12, and by the time I add up the cost of a new compressor, accumulator, orifice tube, and the cost of evac and recharge, it's only a little bit more for the shop to do the whole thing. I could buy the equipment and do the r134 conversion for about the same price, but that's not going to happen now for a number of reasons. I could wait until next summer, but I'm in Phoenix so I'm going to need ac for at least another two months.

Mr. Bones

xzo6

As long as there is even a small amount of green dye at the compressor that means something has escaped or is leaking,enough to lower your freon level to the point where your system isn't going to work.Your clutch seal is the point where the dye is coming from I assume.However if you look at you hood liner and see an oily spot above your compressor then you may have had some of your freon blow off when the system was under too much pressure.Your problem then isn't the compressor leaking.That is a normal safety blow off .If it was just at the hose connection,it would be a simple repair.There are 2 connections like that at the compressor.R12 is was used on pre 1994 vehicles.Sounds like it's time to switch to R134A.The conversion isn't as expensive as it used to be.I don't think you have to change the orfice tube or accumulator(if they are not clogged or corroded from the inside).Double check for a leaks at the condensor(a common area for leaks) .I agree that for the most part that freon escaping is in a gas state ,but there is also some oil mixed with it in the system.Therefore you may find oil residue where there has been a leak. A conversion to R134A is a simple matter of getting the system flushed,and new adaptors to fit the manifold gauges(they are a different size than for R12).They use a synthetic PAG oil now that is universal for all HVAC systems.If you have more questions ,just ask.Try and find a Tech you can talk to who is honest and not trying to upsell you.Your car is older and I am sure you want some cold air right now but don't want to pay a fortune for it.Your compressor does not have to be changed if it is not leaking.It will still work with R134A.Goodluck...

Mr. Bones

When the shop first looked at it after adding dye the guy said that there was a slight leak at the clutch seal. When I looked at it with a black light I couldn't see anything at that seal, but I did see a tiny amount of dye along the seams of the compressor. The seams also look a little oily, but they've looked like that for years. My concern is finding the actual cause of a fast leak. (It went for 6 years then almost overnight it started short cycling. The shop recharged it, and about a week later it was short cycling again.) There's no oil on the hood liner or the pressure valve. I want to be sure of what the leak is so I don't have to take the shop's word for it.

I don't want to get into a big r12/r134 discussion, but one reason I haven't changed is that a number of people (who probably know what they're talking about) have said that r134 will be about 5 degrees warmer than r12. My AC has aways just been barely adequate and in Phoenix those five extra degrees would be a problem. If I could be assured that r134 would work just as well as r12 I would switch now.

Mr. Bones