A/C compressor problems

[bctbct]

93 Chevy 1/2 ton

A/C does not cool. I hear what I think is the clutch engaging over and over for a few seconds. Sometimes the truck seems to have a rough idle when the clutch is kicking in.

Ideas? tia

 

[brblx]

compressor may be starting to seize, or you may already have a slight idle problem that the normal drag of the compressor exacerbates.

i'm not familiar with chevies, but if the compressor cycles based on the signal from a low pressure switch, low refrigerant charge can cause it to cycle quickly since the compressor doesn't have much to suck down. if the switch is on the high side, though, it might actually be a symptom of overcharging.

 

[radioouman]

I'd bet low refrigerant. Get some hoses and check the pressure while the compressor is trying to engage.

 

[bctbct]

thanks, will update

 

[Pacfanweb]

Typically, the compressor cycling on/off rapidly indicates low refrigerant, as previously mentioned. Just get some refrigerant and shoot a can or two in there. If it starts running longer, look for the leak.

 

[bctbct]

Okay, still messing with this repair.

I had a buddy refill the freon and 1 week later the a/c lost the freon. So I have a leak.

Today I dropped it off at a repair shop. They said the compressor was bad (oil aound the housing) they also told me they suspect the condensor has a leak. $1350, no I didnt leave out a decimal point! $50 diagnosis.

Came home and call another shop for a ball park price. They told me they have never seen a condensor go bad on a chevy truck, so they would be very surprised if it failed. Their phone price was $975 which included the condensor.

Then I noticed something else. The compressor hose has a fill inlet(not sure of proper term) that is approximately 10" from compressor. I removed the plastic cap and air escaped. Is this suppose to have a 1-way fitting like a valve stem? Wouldnt this be a way for freon to slowly escape?

The compressor does have a light oily moisture surrounding the front, and there is a light swath of oily substance on the hood liner above the compressor, indicating oil being flung off the compressor. However the amount of oil was not substantial.

I had a hose break on a different vehicle several years ago and the entire engine compartment was soaked in oil.

What do you guys think? Thanks

 

[boomerang]

The fact that they say they suspect the condenser is leaking sounds suspicious. It also sounds like you may have found the leak. There is a valve in that fitting that seals it off. The o-ring on that cap is just to seal out water and dirt, not seal in refrigerant. With the cap off, the valve should seal.

Take it to the second shop and have them diagnose it. IMO, if the compressor is slinging oil, it's time for a new one. If it's not the source of the leak now, I believe it will be soon in the future.

Pay the first shop their $50 if they want it and take it to the second for a diagnosis there.

 

[brblx]

oil is mixed with the refrigerant. if you've found oil, you've found a leak.

 

[drnickriviera]

They suspect the condenser has a leak? Meaning they didn't do shit to properly diagnose it. The system should be filled with nitrogen and a small amount of refrigerant and they need to use a freon sniffer to find the leak.

I do all my own A/C work, so i've never priced anything, but both seem like high prices for me. I just bought a brand new Denso (OEM) compressor for a Lexus for under $300. Condenser, drier, expansion valve(i'll bet they don't even use one) should be $2-$300. Removing parts should be really easy on the truck

 

[dud]

Unless you have converted your A/C system you have an R-12 based system. The last time I needed a recharge on my '93 I was quoted $100 a pound for freon. How much is your truck worth? If you decide it is worth keeping AND you want air conditioning consider just converting to R-134a ... at about $6 a pound.

 

[bruceb]

All the service valves on car ac units are Schrader type, meaning they have a tire like valve stem in them. In this case, I agree with the others. First shop is trying to rip you off. Bring it to the other tech, let them recheck it. Sounds like all it needs is a valve core, system evacuation, leak test and refill of freon. Compressor may be bad, but you won't know until it is charged and they see how the system works and how the pressures are. Condenser failure is extremely rare and is usually due to impact damage or puncture.

 

[bctbct]

thanks for the feedback, I think I will try a third shop and point out the filler valve problem and go from there.

I suspect the first guy saw the oil, figure the age of the truck, doubted I would fix it anyway so he wouldnt waste much time figuring out what was wrong.

 

[exdeath]

You can screw around throwing parts and money at it until you get lucky and find the leak or you can take it to a shop that knows how to work on AC systems and they will run UV dye through the system and find it on the first try.

You indicated everything seems to be working fine until it leaks down. I would leave it alone and just fix the leak, unless you like spending money for no reason. No need to mess with the condenser, compressor, or any of that stuff unless one of those is in fact the source of the leak, which the UV dye test will quickly confirm.

 

[bctbct]

update

found a shade tree mechanic who also suspected the compressor leak because of the oil marks.

he changed out the compressor, replaced the inlet valve, new dryer, and slapped R-134 into the system.

$325 and week and a half later I'm cold. :thumbsup:

 

[boomerang]

Good deal all around! :thumbsup:

 

[slag]

Originally posted by: bctbct
update

found a shade tree mechanic who also suspected the compressor leak because of the oil marks.

he changed out the compressor, replaced the inlet valve, new dryer, and slapped R-134 into the system.

$325 and week and a half later I'm cold. :thumbsup:

I've never seen anyone "slap" r143a into an AC system, but if yours had R12 in it, he should have evacuated any residual, flushed it, used new compatible oil, replaced the O rings, and then refilled it.

I'm glad yours is working, but I'd be leary of it breaking in the not so distant future.

 

[bctbct]

Originally posted by: slag

Originally posted by: bctbct
update

found a shade tree mechanic who also suspected the compressor leak because of the oil marks.

he changed out the compressor, replaced the inlet valve, new dryer, and slapped R-134 into the system.

$325 and week and a half later I'm cold. :thumbsup:

I've never seen anyone "slap" r143a into an AC system, but if yours had R12 in it, he should have evacuated any residual, flushed it, used new compatible oil, replaced the O rings, and then refilled it.

I'm glad yours is working, but I'd be leary of it breaking in the not so distant future.

_________________________________

That quote was $1350

 

[PM650]

I would also be leary about this failing sometime in the future for not being a 'complete' conversion. Unless the truck already had barrier hoses & r-134a compatible o-rings, you may be asking for trouble (also I think you're supposed to replace all o-rings to avoid cross-contamination between refrigerants).

 

[LTC8K6]

I've heard both stories about putting R134a into older systems.

R134a didn't work well or for long, and R134a worked perfectly fine with no problems.

 

[Zenmervolt]

Originally posted by: PM650
I would also be leary about this failing sometime in the future for not being a 'complete' conversion. Unless the truck already had barrier hoses & r-134a compatible o-rings, you may be asking for trouble (also I think you're supposed to replace all o-rings to avoid cross-contamination between refrigerants).

You don't need barrier hoses for R134a. You'd need them for R22, but no-one is going to be using R22 in an automotive system (although the pressure/temperature curves for R22 would actually work out nicely).

The refrigerants themselves are 100% compatible. The "gotcha" is the oils. R134a cannot carry the same oil as R12 and the two types of oils do not mix well (they form a mildly acidic goo when mixed). So, to use R134a in a R12 system, you need to evacuate all the old oil and replace the receiver/drier.

Even doing that will not result in the same level of cooling as with R12 though since R12 has a superior pressure/temperature curve and for optimal performance will need a larger or more efficient condenser than an equivalent R12 system.

ZV