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cant find a/c relay

Discussion in 'General Chevy & GM Tech Questions' started by Nicolaix, May 30, 2011.

  1. Nicolaix

    Nicolaix New Member

    im not sure if there is a current post i tried to find one .. but anyways i cant seem to find where the a/c relay is in my 1990 chevy 2500 4x4 is. . my ac compressor clutch engages for a full spin then shuts off for about three seconds and so on. trying to find the relay for it . hopefully it is the relay but i've never dealt with a/c problems lol
  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    The AC relay is mounted to your FA box. If you can't get access to it from under the dash on the passenger side, then take out your glove box insert to get to it.

    ** From the way you described the clutch I kind of doubt that the relay is the problem Nic. I would bridge the low pressure switch for about 10 or 15 seconds first. If the clutch engages then the system just needs charging.
    Last edited: May 30, 2011
  3. Nicolaix

    Nicolaix New Member

    How exactly do you bridge it
  4. stephan

    stephan Rockstar 4 Years 5000 Posts

    You can use anything from a jumper wire with alligator clips, to a bent wire, or even a paper clip. Anything you have that will make a good connection. Keep in mind that this is only a test & you shouldn't keep it bridged for more than 10-15 seconds or compressor damage could result. Even if it straightens out the compressor clutch operation, & your ac starts blowing somewhat cool, don't be tempted to leave it like this. It's just a test to see if you have enough freon in the system.
  5. Nicolaix

    Nicolaix New Member

    Where do yoy make the bridge at I assume the pos battery terminal to ?

    ---------- Post added at 02:17 PM ---------- Previous post was at 02:03 PM ----------

    Where do yoy make the bridge at I assume the pos battery terminal to ?
  6. stephan

    stephan Rockstar 4 Years 5000 Posts

    NO, not at the battery. You bridge the wires at the low pressure switch. You will find it in the low pressure line near the reciever drier. I have an '88 & it's mounted right on the outside of the evaporator on the firewall. The low pressure line is the larger of the two hoses/lines in your ac system & this is the line that the low pressure switch is in. It runs from the compressor to the firewall.
    There is also a high pressure switch in the high pressure side/line (small diameter line) so don't confuse the two. AC systems are divided into two sides, high pressure side & low pressure (suction side) You are only concerned with the low side & the low pressure switch for this test.
  7. Nicolaix

    Nicolaix New Member

    lol still confused ill have to go to a shop..lol
  8. stephan

    stephan Rockstar 4 Years 5000 Posts

    If you can take a pic of the passenger side firewall, I think I can point it out to you. Make sure there's lots of light.
  9. Nicolaix

    Nicolaix New Member

    ok ill take a pic in the morning thx

    uploading right now lol
    Last edited: Jun 2, 2011
  10. Nicolaix

    Nicolaix New Member

    pics

    ac111.jpg ac112.jpg ac1111.jpg
    here sorry i got distracted by work this morning
    is there enough light in these pictures
    Last edited: Jun 2, 2011

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