Forum Discussion

armyhockeynut's avatar
armyhockeynut
Explorer
Jul 15, 2013

A/C Issues STILL ONGOING

I continue to have issues with the A/C unit in my 2004 Chevy Silverado 2500HD. This has been an ongoing issue for several years and numerous trips to the repair shop. Everytime, someone thinks they "figured it out", it works and then returns to the same old thing. First off, the issue is not that it needs to be "recharged" This is a common repsonse, but that has been check and rechecked and all in order. No leaks either. The basic problem is that the A/C will work fine as long as the truck is maintaining a decent RPM. If we hit heavy traffic or stop and go city traffic, the a/c gives out and never returns even if we get back up to a prolonged period of normal speed. When we are towing the camper it is worse. Friday and yesterday the A/C would not work at all. As we drove I had a volt meter in the cigarette lighter and it was reading around 13.87 when I would turn on the a/c it would only drop to 13.77. Aa most know, yesterday was not a day to be without A/C here in Virgina.
This morning, I drove the truck to the train station and the volt reading was 14.45 and the a/c was blowing ice cold. In thwthe afternoon the a/c blows cold on the ride home too. So I am at a loss.
My gut says that the A/C is not getting the required power it needs to run properly.

Input please!
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  • rickgu's avatar
    rickgu
    Explorer
    Jul 15, 2013
    My 03 had the same symptoms for years and the compressor finally went out. Ever since I've had my truck I've been able to hear the compressor run and thought it was normal but now that I have the new one in I can't hear it run at all. I can barely hear it engage and it's worked perfectly since. My mechanic also replace my orifice and dryer too. But no more sitting in traffic with the AC blowing hot or it shutting off at random.
  • armyhockeynut's avatar
    armyhockeynut
    Explorer
    Jul 15, 2013
    Thank You everyone for the feedback. As I said this is has been an ongoing annoyance over many years. The truck has been to 2 seperate chevy dealers, 2 firestone service centers several times, a repair shop that specializes in trucks, and from all the invoices it appears that every part of the a/c unit has been replaced. The last mechanic to work on it, swore he had it fixed and claimed that he drove it out and thru the city and it worked fine. BS! I appreciate the comments. Will be discussing this with the mechanics at a new shop in hopes that we can come to final diagnosis, repair.
  • jmckelvy's avatar
    jmckelvy
    Explorer
    Jul 15, 2013
    Engineer9860 wrote:
    Check the air gap between the A/C compressor clutch, and A/C compressor pulley. If the gap is at the maximum limit a low voltage may not be creating enough of a magnetic field for the electromagnetic coil to pull the clutch in.


    X2.

    I have a 2000 Jeep Cherokee which had similar symptoms. No obviously bad anything. Turns out the rubber bumper stuff in the AC clutch mechanism had become hard and brittle with age. Worked fine when cool but when everything heated up the clutch would not pull in enough to engage the compressor. I simply removed some of the rubber and it has been working fine ever since.
  • transamz9's avatar
    transamz9
    Explorer
    Jul 15, 2013
    I know this is bad to say but you need to find another A/C man. No one is going to be able to fix this over the internet without seeing what is actually happening. I would need to see what the manifolds are reading and watch what they are doing.

    Couple questions for you:

    Has the system ever been opened?
    Has the compressor been replaced?
    Is the condenser clean?

    There could be a number of things that could be causing this but your voltage is fine.
    It could be as simple as the $2.00 orifice. You could have a blend door problem in the dash. Could have too much freon. It could have too little freon and freezing up. It could be a weak compressor. Compressors can work fine at low RPM and then not work at higher RPM.

    Like I said, without having the manifold gauges hooked up in front of me it could be a number of things. I had a Dodge dealer warranty a compressor 4 times in two months and it ended up being the orifice tube. I had to do the work myself to get it right. PM me if you want to talk about what's going on with your truck (what's been done and what they are telling you) and we can seen if we can get you cooling. A/C systems are not hard to work on it's just everything has to work properly or it won't work at all. The hardest part is figuring out what's not doing it's part. ;)
  • Engineer9860's avatar
    Engineer9860
    Explorer
    Jul 15, 2013
    Check the air gap between the A/C compressor clutch, and A/C compressor pulley. If the gap is at the maximum limit a low voltage may not be creating enough of a magnetic field for the electromagnetic coil to pull the clutch in.
  • ryhed's avatar
    ryhed
    Explorer
    Jul 15, 2013
    Anyone put stop leak in it? it makes the inside of the refrigerant lines smaller and it could make it quit working efficiently. I would probably buy all new lines a drier and clean the condenser. Make sure your fins are clean and straight on the condenser. Is the blend door operating correctly?
  • JRS___B's avatar
    JRS___B
    Explorer
    Jul 15, 2013
    Is the compressor engaged when the unit is not performing?

    I can't believe no one looked to see if the compressor is turning or not.

    If it turns out to be a bad clutch, or wiring to the clutch, or a relay for the clutch, then you need a new mechanic as well.
  • Dr_Quick's avatar
    Dr_Quick
    Explorer II
    Jul 15, 2013
    I do not think that the voltage is a problem. Some things come to mind. If everyone thought that system was low on refrigerant and added some, an over charged system can shut down due to high pressure. Could be that pressure switch is bad and causing system to shut down, when in traffic and lower air flow would cause pressure in system to rise. Not sure of his one, but when in traffic, temperature of engine will rise. Possibly since AC running at the time could cause computer in vehicle to shut down AC to "save engine" from over heating, due to extra heat proceeded by AC system.

    Has anyone tried connecting a computer to OBD port, and road testing the vehicle under the conditions that you describe? This could possibly help to view system pressures and temperatures to see if they are normal, or excessive.

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