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A/C problems

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by rileyjr16, Jul 30, 2014.

  1. rileyjr16

    rileyjr16 Rockstar 3 Years 1000 Posts

    Ok guys. I first noticed a problem with my A/C was on my way to DC for the 4th of July weekend. I had developed a freon leak and I bought some stop leak and some refrigerant and replaced it and all was good and cold for about 2 weeks. Well last week, I noticed the same thing happened. Put some more freon in it to fill it back up but that only caused my current problem. Ok, so when the truck is low on freon, I jump the switch off (with a paper clip in the pigtail) under the hood to the condenser to kick the compressor on to start pumping freon. When I do that, it usually works. Well I put some freon in the truck again with the A/C on full blast; with the A/C switched on, the compressor will kick on for 1-2 seconds and kick back off like its got too much freon in the system. When I jump the switch off, the compressor kicks on and stays on the whole time it is jumped off but I have no cold air whatsoever inside. The pressure in the system rises when the compressor kicks on and drops when it kicks back off. Now, the compressor will not kick on at all like its out of freon again. Now I know that I have a leak SOMEWHERE. Finding it is the problem. The clutch is good on it, it spins when the compressor kicks on and stops spinning when it kicks off so chances are its not that.

    I'm at my wits end. Can a mechanic tell me whats leaking and where so I can replace it or is it something that a mechanic SHOULD do?

    Could it be a the blend door, the condenser or the compressor or just a very fast leak somewhere? Its getting hot here...
  2. poncho62

    poncho62 Member 1 Year 100 Posts

    They put ultraviolet dye in it to find the leaks. That stop leak crap sometimes does more harm than good.
  3. rileyjr16

    rileyjr16 Rockstar 3 Years 1000 Posts

    So mechanic bill here I come... $$
  4. WorthFlorida

    WorthFlorida Member 2 Years 100 Posts

    Any closed system has high pressure and low pressure sides. If you think the refrigerant leaked out fast then look at the high pressure side, slow leaks the low pressure side. Since the compressor was cycling on for a few seconds means that the low pressure switch opened up and disconnects the power (12v) to the compressor clutch.

    Common area for leaks are hoses, the evaporator core and sometimes the compressor. You didn't say how old your truck is but if the odometer is in the six digit range, most likely this will be your shopping list: compressor, dryer, high pressure side hose and an orifice tube. An A/C mechanic should have a refrigerant leak detector (sniffer) to localize the area of a leak but the die pumped into the system and all connections checked with a ultraviolet light is the sure thing.
  5. j cat

    j cat Rockstar 4 Years 1000 Posts

    leaks can happen any where . the black light dye will reveal the leak. with this in the refrigerant , using a black light the dye will show the leak location. common areas of leaks are the condenser,compressor[body or shaft seal]high side test port,the metal fittings . even that low pressure switch .

    1999 is old so a compressor is a suspect at this age...look for any oil stains.

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