1998 s10 a/c leaks... help!

i have a leak in the a/c system and i cant seem to find a leak. i used my friends a/c leak detector (the sniffer style) and i came up with nothing. i removed the evaporator and dunked it in water and ran 90 psi compressed air through it and no bubbles were seen. where are leaks most common on these vehicles? anyone else had an a/c leak and found it? give me some ideas where it could be coming from. here is what i have checked so far. first i charged the system and let it run for a few minutes and then shut it off. i checked the compressor inlet and outlet fitting, evaporator inlet and outlet fitting, condensor inlet and outlet fitting and any crimp connection i could find on all the lines.

Not at all unusual for the compressor itself to be leaking around the case seal. Do you see any oil around or under the compressor? Oil leakage is a dead giveaway of a refrigerant leak.

thats what i was looking for too. there is no signs of oil leaking anywhere. i have been sniffing and sniffing for refrigerent leaks but still cant find anything.

I have a leak in my 1997 and it is around the schraeder valve on the high pressure side. It is small enough that you cannot tell it with a detector as the leak is so small, but when I unscrew the plastic cap, I can see oil in the schraeder valve area and also under the cap. I can clean it and put the cap back on and check it after a while and the oil has re-appeared. This, from what I understand is a common leakage area for S-10's around our vintage.

What type of detector did you use?? Was it for 134a refrigerant? Did it have a pump in the unit to pull more air/regrigerant into the sniffer area to be more sensitive? Just curious.

later...

eti engineer

Another very common place for leaks is at the compressor shaft seal. It's behind the clutch and pulley so sniffer type detectors usually can’t get close enough to the leak to detect it. The best form of leak detection is adding a florescent dye to the refrigerant and use a black light to look for the florescent dye leaking out. Works every time!

As old master said.
For the hard to finds leaks they make a leak dye test kit.
Add dye and run it a day or two and put the light on it and the leak will usully show up real yellow.
Most auto parts places have it.
But if it comes with stop leak pitch the stop leak in the trash can and just use the leak test dye.
MT

not to insault anybody who thinks otc a/c refridgerents are any good in any way shape or form, sorry, your wrong, this is one system you do not want to mess with yourselfe by using those damn 12 oz cans, you can hurt yourselfe (reasons r134a has 2 different sizes, on high one low, r12 had one size shrader valve, and several incodents with filling the r12 into the highside blowing the can up caused this, the ac pressures and temperatures are nothing you want to mess with in your back yard, pay someone to fix it), in my opinion, saving a buck isnt worth what you could mess up on the vehcal with what they put in those cans (sorry to burst any ones bubbles, but those cans are pure knock off shit, not what you get from an ac shop) or mess up on you by doing something backasswords

Dmbrisket,

Unless you have an old set of R-22 or R-12 gauges, it is not possible to fill on the high side of the S-10 AC system, and even then, the gauges would be of no use, because the numbers on the gauges are for R-12, R-22 and R-502 refrigerants. That is the reason the two valves are constructed totally differently. You cannot attach the fill hose from the currently available AC fill kits to the high pressure side. They are idiot-proof.

I also beg to differ with you on your assumption that the cans of 134a are "knock-offs". Do you know how long it took the chemists to come up with R-134a? It took forever, and there is still no replacement for R-22, which is actually heavier than air (R-12 was not, and that is why it had such an effect on the ozone layer). Once R-12 breaks down in sunlight, some components can rise to the atmosphere and supposedly create problems similar to R-12. Since it takes so long to develop refrigerant replacements which are environmentally friendly, I doubt these are knock offs. They have to have certain chemical properties to work correctly within the system without breaking down the components of the system itself. AC is created by constantly changing the state of the medium used, and the properties of that medium have to be special to allow the system to do its job.

I was a residential HVAC contractor for over 13 years and have all my licenses and do my own work, still, just in case you wonder if I am blowing smoke.

It is safer now for people to work on their own AC systems than it ever has been. I agree, that if you know absolutely nothing about it, maybe it is safer to have someone else do it, but a minimal amount of reading the instructions should allow anyone to at least recharge their system. It ain't rocket science...

Later...

eti engineer

I made a mistake.

I meant to say in the second paragraph, "Once R22 breaks down in sunlight, some components can rise to the atmosphere and supposedly create problems similar to R-12." I wrote, "Once R12 breaks down..."

later,,,

eti engineer

Unless you have an old set of R-22 or R-12 gauges, it is not possible to fill on the high side of the S-10 AC system, and even then, the gauges would be of no use, because the numbers on the gauges are for R-12, R-22 and R-502 refrigerants. That is the reason the two valves are constructed totally differently. You cannot attach the fill hose from the currently available AC fill kits to the high pressure side. They are idiot-proof.
eti engineer

I might add that the same holds true with any system requireing R134a refrigerant, (not limited to S-10).

the otc r134a cans usually (no not alwase but most of the time) contain Butain, which is corrosive, flamable, and just dangerous in the ac system, when 12 and 22 come into contact with flame or any sorce of heat (ie the sun) it makes phosgene (sp???) gas and that is what is harmfull, yes they have idiot proofed the new cars (all not just s 10 or gm, federal mandate) have different highside lowside hookup sizes, my main point and still argument was that the over the counter stuff, even though as you said, should be, pure 134a with oil, it is not, the aftermarket put lots of goodies in it to get the same phase change effect with cheep stuff in their mixtuer. Why? because to them it doesnt matter they are not liable for what you do to your vehical and they can make a buck off of you.

the otc r134a cans usually (no not alwase but most of the time) contain Butain, which is corrosive, flamable, and just dangerous in the ac system, when 12 and 22 come into contact with flame or any sorce of heat (ie the sun) it makes phosgene (sp???) gas and that is what is harmfull, yes they have idiot proofed the new cars (all not just s 10 or gm, federal mandate) have different highside lowside hookup sizes, my main point and still argument was that the over the counter stuff, even though as you said, should be, pure 134a with oil, it is not, the aftermarket put lots of goodies in it to get the same phase change effect with cheep stuff in their mixtuer. Why? because to them it doesnt matter they are not liable for what you do to your vehical and they can make a buck off of you.

i couldnt find anything with the a/c leak detector so i just charged the system and sprayed soapy water all around and it turns out the high side recharge fitting was the leaker. very small leak. went to the dealer and it cost 7.00. first time i ever went to the dealer and didnt spend over 100.00 :)
thanks for the help guys....

If you're buying a can that is clearly labeled r-134-a it IS the right stuff. Knockoffs usually tweak the name. They make straight r-134, r-134 with oil and r-134 with oil and stopleak. I wouldnt use the stopleak one, bad news. The only bad thing about using the 134 with oil is that there is still oil in the system and you run the risk of putting too much oil in the system. You can look on the can and see what is in the refrigerant too.

it is against the law in the us to produce and market any "freon" replacement for use in automobiles that contain butain/propane or any flamable compound.