Auto AC help

Pipefighter248

Pipefighter248

Donating Member
Registered
97 Chevy Blazer

Stumped here and needing some advice from a mechanic on the board or someone very knowledgeable on automotive ac systems.

Since I had the blazer it has had a very small leak somewhere in the lines. Would loose a charge after 6+ months.
Last year I replaced the o-rings on top of the compressor and at the drier hoping that it would close the system again.
Well it only took roughly one day before it was drained again; so the leak was of course worse.
Didn't fix it then since it was close to fall and the weather wasn't as warm.
Well today I go out and buy all new OEM o-rings(don't get me started on the price of them :banghead:)
Got home and started pulling a vacuum.
Pulled vacuum for about an hour and decided to just test it to see how quick it would loose it's vacuum.
Well after 2 hours it hasn't lost any at all.
Still holding at 28ish in hg.
Did not change a thing and it now seems to be holding.
I'm going to let it sit overnight to see if anything changes before charging it.

I know there is a chance that the schrader valve on the low side port might now have sealed last time I charged it; but there were no audible leaks and I charged it with the Refrig that has uv dye and can still find no traces of a leak with black light.

Any advice or suggestions on what it could be or what to do?
 
Did you eye ball the evap? You may not see a drop because 28in hg isn't anything.
You need to check it when the system is operating.
 
Take a good look at all the lines and especially the condenser in front of the radiator..Also
make sure the nose of the compressor is dry. good luck
 
Check the evaporator close but I've had more problems with compressors on that model. Believe me, a slow leak is a SOB to find sometimes. If it has rear air be sure to check the lines and the rear core. Good Luck.
 
we find a lot of links on hoses that have the crimped manifold type fittings on them. If you could put some dye in the system and black light it, you might find the leak easier.
 
shadetree57 said:
Check the evaporator close but I've had more problems with compressors on that model. Believe me, a slow leak is a SOB to find sometimes. If it has rear air be sure to check the lines and the rear core. Good Luck.
Click to expand...

I'm going to do a visual before filling it back up since I ran the dye last time.
Also, be putting more dye in this charge.
No rear air.
If I could get it back to where it would last 6 months again I would be happy.
 
AZ Glen said:
we find a lot of links on hoses that have the crimped manifold type fittings on them. If you could put some dye in the system and black light it, you might find the leak easier.
Click to expand...

Have already tried the dye.
Going to put more in when I charge it.
 
Replace the Shrader Valves on both High and Low Sides. That will fix your Problem. Last Time you did the A/C Service one on the Valves did not SEAL Correctly. That's why you lost Your Freon in one day.
 
Bosshound said:
Replace the Shrader Valves on both High and Low Sides. That will fix your Problem. Last Time you did the A/C Service one on the Valves did not SEAL Correctly. That's why you lost Your Freon in one day.
Click to expand...

yes the shcrader valves are notorious for leaking, before you put the plastic caps back on the schrader valves, clean them real good, and put a small piece of cotton under them, then if you ever remove the caps and there is an oil residue you know they are leaking. the comp. shaft seal may be leaking as well, or the evap may be leaking as well but it sounds like you got a good start.

the vacuum test may not always tell the whole story as vacuum is a diff. story than the high pressure created in an a/c system. You made the right move buying the oem o-rings....expensive, yes, better than the cheap made parts house o-rings that may not have been the correct thickness...yes.

let us know how it turns out.
 
whew... the best indicator you have without a leak detector is oil residue.. AC systems carry a decent charge of oil and where freon leaks it will "usually" take an amount of oil with it.. GM had problems with just plain old porous lines and crappy hose connections (the crimps) The odds of being just an oring leaking? pretty low..

Schrader valve leaks: overcome by replacing the caps.. yea they leak but if the service port caps are replaced, they will hold freon in the system. I would not put cotton under them as that is a path for freon to leak out if the cap seeps.

Hose crimps: you will see aluminum bands around the hose ends, yes big on leaks, a good possibility, again look for oil residue.. as your system is running down in a day or less, you have a LARGE leak..

Evaporator leaks are pretty darn rare. Chrysler (K cars) and Lincoln had some issues for a couple years but mostly evaporators are replaced due to physical damage rather than "going bad"

Just start at the compressor.. Look closely at the snout on the compressor (where the pulley and belt is) look for excessive oil sling that may have come out the front of the compressor and any other oil on the thing.. Compressor cases are potential big leaks also along with that front seal.. if you can see oil, you may be seeing the problem.

Now just start tracing the lines starting at the compressor discharge to the condenser. Again just start hunting for oil.. (you could put an oil charge on the system to supplement the thing but only add one)

Be glad you do not have rear air :) if you can not find the oil leak, get some soapy water and spray the hose ends where they are crimped to the aluminum hard lines (larger low side lines) and watch for bubbles where the rubber meets the fitting.. (and yes you need to have freon in the system for this part :) )

you have a large leak so should not be that big a deal to find.. i am going to guess it is the manifold assy off the compressor myself.. (what we replaced the most of)
 
Mr Bogus said:
whew... the best indicator you have without a leak detector is oil residue.. AC systems carry a decent charge of oil and where freon leaks it will "usually" take an amount of oil with it.. GM had problems with just plain old porous lines and crappy hose connections (the crimps) The odds of being just an oring leaking? pretty low..

Schrader valve leaks: overcome by replacing the caps.. yea they leak but if the service port caps are replaced, they will hold freon in the system. I would not put cotton under them as that is a path for freon to leak out if the cap seeps.

Hose crimps: you will see aluminum bands around the hose ends, yes big on leaks, a good possibility, again look for oil residue.. as your system is running down in a day or less, you have a LARGE leak..

Evaporator leaks are pretty darn rare. Chrysler (K cars) and Lincoln had some issues for a couple years but mostly evaporators are replaced due to physical damage rather than "going bad"

Just start at the compressor.. Look closely at the snout on the compressor (where the pulley and belt is) look for excessive oil sling that may have come out the front of the compressor and any other oil on the thing.. Compressor cases are potential big leaks also along with that front seal.. if you can see oil, you may be seeing the problem.

Now just start tracing the lines starting at the compressor discharge to the condenser. Again just start hunting for oil.. (you could put an oil charge on the system to supplement the thing but only add one)

Be glad you do not have rear air :) if you can not find the oil leak, get some soapy water and spray the hose ends where they are crimped to the aluminum hard lines (larger low side lines) and watch for bubbles where the rubber meets the fitting.. (and yes you need to have freon in the system for this part :) )

you have a large leak so should not be that big a deal to find.. i am going to guess it is the manifold assy off the compressor myself.. (what we replaced the most of)
Click to expand...

Good advice Randy.
Did the soapy water test last time I put Freon in it and found nothing.
Remember, plumber so I know how to do such like that.
The best way would be to find a electronic sniffer, If it leaks bad this time I may try to find someone that has one. Even if it is a residential ac shop.
Not giving up yet.
Thanks.
 
if you are loosing 3-4lbs of freon over 24 hours, you have a pretty good size leak going.. sniffers work ok but are subject to "false" alarms no matter how good they are. They also blow if you are trying to use them outside.. (no breezes, fans or other air movement is best) Freon falls down when it leaks so run your check at the bottom of hoses and not over the top of them..

See if you can "twist" the rubber lines (not godzilla style).. if you find one that spins pretty easy on the metal line, you could have the culprit.. (a hose clamp MIGHT fix the problem but dont count on it)
 
should have mentioned "hose blisters" too.. soggy oil soaked blisters on the hose.. The blisters are not so common on new hose (new hose has perforations to relieve any gas that gets that far) but it will still be "oily"
 
No loose hoses at crimp fittings.
Everything is tightened up, pulling final vacuum, and then will charge.
Gonna charge with some oil in case it's low, refrig., and dye.
Hope for the best.

I at least did some good yesterday; replaced the driver side door pins and bushings.
Door was sagging bad. :thumbsup:
 
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