OK - I think I may have buggered up my A/C system... When I bought my 2000 LT it had a leaking compressor but I figured since summer was almost over I would just add some stop leak and it would make it until next spring and I'd replace the compressor then. Well - the oily residue at the rear of the compressor dried up and it worked great for about a week - blew cold just fine - and then started not working great so I added another can of 134a with stop leak and then a can of oil charge but it didn't make any difference - not so cold air anymore. I noticed today that when I first start the engine the compressor will cycle for about a minute - then goes into a 5 second on/30 second off cycle pattern. When the compressor kicks in the outlet hose jumps noticeably and when the compressor kicks of it kinda sounds like a pressure release happens - kind of a little "pffft" sound. I didn't notice the little sound before.

Sooooo - have I clogged something with the stop-leak that shouldn't be clogged - like the orifice tube maybe? Is it possible to tell what is clogged if that is indeed the problem?

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Did you have a gauge when you put the oil and AC fluid/stopleak? If so make sure you didnt over fill as that would cause problems with the AC system as well.

 

I would recover the system and take a gander at that orifice. Youre most likely right about that.

 

Well evidently I messed up something - went out earlier to go pick up my kids from school and when I started the Blazer a puff of smoke/vapor came from under the hood. Checked and it seems to have blown a seal or something on the back of the compressor as there is a lot of fluid/oil shot out the back of it.... friggen luuuvly [:'(]. Well guess I'll be replacing the compressor a lot earlier than I thought. Question now is what should I look to be replacing besides the comp and O tube? Think maybe the condenser is clogged? Kinda concerned due to the way that hose was bucking when the compressor was kicking in (albeit ever so briefly).

Is there a seal on the back of the compressor that could be replaced to salvage it? I see O'Reilly's has both a seal and a pressure relief valve listed on their web site. The compressor was apparently working fine until something got clogged and then the seal or something gave way....

@Lenny - Nope - no gauges - never have used them - always just put in juice til the compressor quits off-cycling and it blows cold - done it on a few cars I've had over the years. Like I said it was working great until something apparently became clogged.
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It's recommended you replace the accumulator as well. Also, be sure to use new o-rings.

I recommend you pick up a manifold guage set. At a minimum you should have a pressure guage on the r-134 you're putting in. Wal-mart has them as does auto parts store. I got mine in a conversion kit, at the time I replaced the evap core on my truck it was cheaper to buy a conversion kit that came with 3 cans of r-134 with oil and a gauge than to buy the gauge and a couple cans for r-134.

- Dan M

 

So should I go ahead and replace the condenser as well as the accumulator? What about this -- I read in a thread I found by searching where you can bake the accumulator in an oven for 5 hours to dry out the dessicant and re-use it? Or do you figure the stop leak has gummed it up too bad to rejuvenate? Also what about the compressor - can I salvage it by replacing gaskets or seal or the pressure relief valve? And again - would it be ok to re-use the condenser - and just replace the orifice tube?

Thanks again for the great help I've found and continue to receive on this forum [sm=yeahsmile.gif]
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I would check the condenser before you replace it, it's not too difficult to disconnect the condenser and run some acetone though it to clean it out. Most of the gunk gets caught in either the orifice tube screen or in the accumulator though. When I re-did the A/C in an old Sunbird, I ran acetone through the whole system (compressor and accumulator removed) by pouring some in and circulating it with shop air, and then removing ALL of the o-rings and replacing them... turned out to be like-new performance when the system was reassembled and properly filled with A/C oil (after being under vacuum for a good long time to remove the acetone, of course)!

I've tried the baking the accumulator trick in the past, works OK oncebut keep in mind you won't remove anything but moisture from the accumulator doing it, so if you've got other gunk in there it would be better to spend the money on a new accumulator to save your new compressor from premature failure.

 

[align=left]Thanks for the info Cruiser. Now this is really weird.... I just went out to see if I could determine where the leak was originating (removed the air cleaner hose so Icould see better) and couldn't see any sign of leakage. So I started the engine - turned on the A/C and quickly jumped around to see where the leak was ... and there was NO leakage. None at all. The compressor was cycling, pumping and was quieter than before. I checked the air from the vents and it's blowing cold. The compressor is kicking out after running about 45 seconds - then is off for about 15 seconds and then cycles again. The noticeable buck in the line to the condenser is now not nearly as severe as the other day - just a slight bump.

On the compressor - one line is very cold and the other is very hot -- is that how it's supposed to be?

Could the stop leak have stopped whatever was leaking the fluid out the back? Is the pressure relief valve I saw on O'Reilly's website located on the back of the compressor? Could the valve have discharged the excess pressure? Could some sort of backflow dislodged what was causing the blockage if there was indeed one? As you can tell I'm really puzzled here....
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I haven't looked at the back of the A/C unit on my blazer, but I know a lot of A/C compressors from GM have overpressure valves on the back, they pop if the head pressure gets to high to vent the freon, until the pressure gets low enough, then they close (usually). Because you are getting cold temps at the compressor on the inlet, it's probably undercharged now, but what is suspicious is that the hot side is still really hot at the compressor... usually it's sort of lukewarm/coolish on the inlet and hot on the outlet. I would definitely put a set of gages (high and low side) on to check it before you consider adding more freon. The cycling tells me that the pressure switch thinks the low side pressure is too low, but this needs to be verified. If the stop leak stuff clogged up the orifice tube, that would make the high side pressure artificially higher, and also cause the overpressure valve to blow even though the system is not overcharged.

Long story short... get some pressure gages and post the high and low side readings when you get them! Don't run the compressor more than you need to.

 

Thanks again for the info Cruiser. Well it happened again (the cloud from under the hood) yesterday afternoon when I started the Blazer to go pick up the kids from school. This time I left it running a looked under the hood and could see no fluid leakage (but there were signs of additional discharged fluid under the hood) by the time I got the hood open and looked. The compressor was cycling at about :30 on / :10 off. So I turned the A/C to full and opened the doors and the compressor stayed on full with no cycling and the air was cold...??? I did some research at the ackits.com forum and found there are 2 GM compressors that look like mine - the HT-6 and HU-6 - both have a pressure relief valve on the rear.

Seems we're making progress on the diagnosis - now to determine the cause of the seemingly intermittent blockage issue. Going to the Zone to get front wheel hubs - guess I'm gonna check on a set of guages too
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