~ A/C questions ~

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nimrod.sixty9

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Just wasted about $70 in freon, oil, stop leak. Charged it up last night and today noticed the compressor was already cycling. Spayed water and noticed bubbles coming out of the ring in the middle of the compressor. Even when I believed the system was fully charged it never seemed to get very cold. Think I could get away with replacing the compressor, orifice tube, and the accumulator?

Also, sometimes the A/C lights blink. I also noticed that the lights sometimes stays on even if the A/C isn't on. They do go off after I depress them. is this normal? Does the blinking signify something else faulty in the system? I just don't want any surprises after spending 214 on parts and another bill on freon just to have no A/C.

Thank in advance!
 
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nimrod.sixty9

nimrod.sixty9

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What a pain this has been.

Wth is that plug that goes in the back of the compressor? The thing got pretty mangled trying to get the thing out to put in the new compressor (I still cant believe it didnt come with it). Seeing how I have yet to charge it (due to a leaking high pressure valve), I would like to just go ahead and replace it. Just dont know what it is.

Ive also noticed the new accumilator is much smaller than the one I took off. Should this affect anything?
 

SunlitComet

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the switch in the back with wires is the high pressure switch. it is second to last resort protection. if to high it kills the a/c request to the pcm to prevent pcm from trying to turn compressor on. the center valve without wires is last resort blowout valve in the event pressure can not be contained safely it will blow out prevent a catastrophic explosion in the system. It will just run dry, bind up and burn out the serpentine belt instead. But the truck survives. If both are not new replace each one.

As far as the accumulator it sounds like you got the wrong one. You have the oem gm numbers off the old one?
 

letsbangout

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Also, sometimes the A/C lights blink. I also noticed that the lights sometimes stays on even if the A/C isn't on. They do go off after I depress them. is this normal? Does the blinking signify something else faulty in the system? I just don't want any surprises after spending 214 on parts and another bill on freon just to have no A/C.

Thank in advance!

If you mean the compressor is staying in, even when the AC is set to off, check your rear AC controls if you have them. Mine is a bit strange in that regard, sometimes the rear AC will hold it in, sometimes it won't. But generally if I never turn on the rear AC, I never have that happen.
 
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nimrod.sixty9

nimrod.sixty9

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The A/C doesnt get stuck on, I was just curious because of the inconsistency with the lights.

Well, I have another issue. Seems the A/C doesnt cool as well as I had hoped. And I noticed yesterday out of nowhere it seemed to get warmer (still cool, just not so much). Turned off the A/C button and back on and it blew cool again. Happened again about an hour later, right before we turned off the truck. When we got back in, it blew cool again. Been fine ever since.

Considering this, and it lacking the ability to impress me with the temps; what could be wrong?

Please advise... Ive already spent enough money on this to not have it work properly.

TIA
 

SunlitComet

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observe it a bit longer and see what happens. I could only guess there might have been a temporary blockage in the orifice tube.
 

letsbangout

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In theory, you should've been able to get away with replacing the compressor, o-tube and accumulator. However, like SunlitComet said, I'm curious to know what your old o-tube looked like. Was the screen completely clear? Was the plastic part of the o-tube still a dull yellow? If the answer was anything but a definite yes, chances are you've got some "black death" in your system, caused by a compressor starting to go. If that's the case, you'll be putting in some work. You'll need to disassemble everything, shoot flush chemicals through it (in both directions), dry it out (SunlitComet says to use dry nitrogen - definitely use it if it's available, though most shops don't have nitrogen and seem to do fine), charge with nitrogen to check for leaks (again, if you have nitrogen), purge the system, vacuum it down, then use the vacuum to charge as liquid, then as gas. If you do have black death, you can't possibly solicit enough advice from people who have done this before.

I've heard (from a GM tech) that the condenser on my truck (99 Yukon, not sure about others) is parallel-flow, and that despite all of the TSBs I've read from GM saying it'll be fine to re-use it, he says it's not fine, and he's never re-used a condenser where he knew there was catatrophic failure or particulate in the system. The only way you could realistically flush a parallel flow condenser is probably with a HECAT or similar device (a liquid pressurized closed-loop flusher, usually available only at high-end shops, will likely cost you as much for this service as a new condenser, which IIRC is about $110, AND you may be able to sell the old condenser to a metal scrap outfit and cop enough money for a trip to Sonic or McD's!). Consider that all GM dealerships have one of those machines, and my friend still says don't do it.

Also, if you have rear AC, you absolutely must remove the rear evaporator and disconnect the expansion valve and flush the pipes individually, and the evaporator individually, as the TXV won't let you flush through it (might be a good time to replace the TXV too, since its only 50 bucks). Contrary to popular belief, getting to the rear evaporator is not as much of a pain in the ass as everyone thinks it is. Just remember that those rear hoses curve upward when they reach the firewall, so you'll need enough air pressure to push the flush and the air up and out (maybe someone has better advice for you in that regard). Also you can't realistically flush through the high and low side hoses (unless they don't have mufflers - but all of them do by default), so if you suspect the death, you should replace them. FYI, mine had a problem with warped threads on the rear pipe, probably due to the pipes and the rubber hoses having two different types of metals, though they don't seem to leak. Finally, when assembling everything, add oil according to Delco's "oil balance card" that tells you how many ounces go where. It's like 3 for the compressor, 2 for the accumulator, 2 for the condenser, etc (but check it first! don't take my word for it. In fact, don't take my word for anything, do your own research and ask plenty of questions - it'll save you time and money). That document assumes a brand new or completely clean component that has no oil in it.

One final word of advice - double-check Alldata or the Helms manual for your truck on capacities, unless you still have the old accumulator, which I understand has a capacity sticker on it. I managed to find multiple incorrect sources on the Internet, including a Haynes AC manual, that says my truck takes 4 pounds (?!@#$) of refrigerant - in fact the correct spec for my truck with C69 (rear AC) seems to be 2.75 lbs. Overcharging to that degree would surely blow up that new compressor of yours. Hopefully that hasn't happened already. Overcharging can certainly limit the effectiveness of your system in direct proportion to how overcharged it is.

Oh and then there's this. GM recommends in cases of catastrophic failure (which doesn't sound like it was the case with yours, though you might still have a little bit of "black death" in your system if your compressor was on its way out, i.e. if you ran it with too little oil, which is usually the case when you have a leak and recharge it a few times).. that you install a screen on the suction side that fits down into the compressor's low-side input, to protect the compressor from solid particulate that might make its way up to the compressor, and a liquid line filter to trap solid particulate in the filter (though from what I can tell by the pictures of this particular Delco filter, it seems to screw in *after* the orifice tube, making it's effectiveness questionable based on my lay knowledge of AC systems). But I think that goes back to the subject of the condenser - if you have a clean condenser and a clean system, your o-tube shouldn't get dirty at all.

Personally, I'm at the point where I need to recover and inspect my o-tube to see if I have more black death in my system. I had a catastrophic failure and I didn't know the condenser wouldn't flush well. I have a feeling i'll be replacing it - I replaced pretty much everything except the evaporators at this point. I may also install a suction screen but I'm not sure I see the point of a liquid line filter, yet.

Good luck!
 
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nimrod.sixty9

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Now thats informative! Thank you for taking the time to lend me a hand!

Now as for for my old oriface tube... Not so good. It was full of complete crap, couldnt eve see through it; nothing black though. Almost all covered in red, which is likely due to the stop leak I had tried first time around. I had added 4 12oz cans of 134a and 1 3oz can of PAG100. Didnt get cool till the third can and it wouldnt take all of the 4th can. Is it possibly due to low oil? Whats your take on whet I had done?

Thanks!
 
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SunlitComet

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low oil would not cause a cooling drop-off. it is better to charge your system based on the performance test and not just poundage.
 

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