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  1. #1

    Where is the low AC pressure switch?

    I was looking over at a 1990 (but I have 1991) Pontiac Grand Prix service manual that I got from the library and I was trying to find out where the AC pressure switch. The book shows that its on AC compressor along with the high pressure switch but when I looked I couldn't find any connector except for the clutch. I also noticed that there is some connector on the accumulator (big silver tank under air filter) . I need to know so I can refill my system and I need to check if my clutch works.Where is the low pressure switch?
    91 PONTIAC GRAND PRIX LE SEDAN
    <br />110k miles, 3.1 MPFI

  2. #2

    Where is the low AC pressure switch?

    CAN ANYONE HELP ME!!!!!!!!!!!!!!!!!!!!!!???????????????????????
    91 PONTIAC GRAND PRIX LE SEDAN
    <br />110k miles, 3.1 MPFI

  3. #3
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    Where is the low AC pressure switch?

    testing the clutch is easy, have sum1 start ya car while your under the hood, let it run for 10-15 seconds with the ac off, then have em turn it on and listen for a click, if u hear it, it works, otherwise, it doesnt.

    as for a low pressure switch, im not sure, my 90 doesnt have 1.

    -Jeff
    Baby Daddy

  4. #4

    Where is the low AC pressure switch?

    I know how to test the clutch but you see the ECM disables the clutch when there is not enough refrigerent. I want to find out if I can get my AC working again by checking if I have all the sensors. I think my AC freon just leaked out because of time and winter , I don't see anything broken or rusted away.
    91 PONTIAC GRAND PRIX LE SEDAN
    <br />110k miles, 3.1 MPFI

  5. #5

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    Where is the low AC pressure switch?

    my brother needs to recharge his system.... but his compressor still engages, try turning on the defrost then, it'll make the AC compressor kick in
    <br />1993 Chevrolet Lumina Z34 &#39;POS Heavyweight&nbsp; Off-Road Special&#39;&nbsp; -&nbsp; Gone to the Great Junkyard in the sky!<br />(sig pic resized)<br /><br />Currently driving: 2005 Blazer - 5 speed, 4x4

  6. #6

    Where is the low AC pressure switch?

    It does not engage the compressor because the computer knows from the sensor that pressure is low. but I think if the can is under pressure then the refrigerent should go in without the compressor being turned on. But you see I wanted to save the trouble and I want to actually find the pressure switch.
    91 PONTIAC GRAND PRIX LE SEDAN
    <br />110k miles, 3.1 MPFI

  7. #7

    Where is the low AC pressure switch?

    Quote Originally Posted by gp90se
    as for a low pressure switch, im not sure, my 90 doesnt have 1.
    If your 90 has AC, then it DOES have a low pressure switch. I have the 90 wirring diagram right here on my desk

    And GPdriver is right..the A/C WILL be disabled if there is low pressure. That's what the switch is there for. I'm running into the same problem right now on my TGP. Someone suggested to just jump live current to the AC directly and see if the pump will spin. I haven't gotten around to doing this yet though.
    1990 Grand Prix LE Coupe - Beater<br />1990 Grand Prix TGP Coupe - Resto Project #1<br />1990 Grand Prix TGP Coupe (#2) - Resto Project #2<br />1994 Dodge Ram 2500 8.0L V10 Reg. Cab Longbox 4x4<br />1992 Grand Prix SE Coupe - Dune Buggy Project<br />1999 Grand Prix GT Coupe - Sunday Driver<br />2002 Chrysler 300M - Daily Driver

  8. #8

    Where is the low AC pressure switch?

    I went to the wreckers and I was looking at a 1990 (I believe)GP and the AC compressor was in the trunk, it had two little plugs on the side and the slots for the refrigerent lines. I checked on my GP the only AC sensor I can see is one near the accumulator nothing else, I was even looking at a 1992 GP and it didn't have any wires near the AC compressor except for the clutch.
    91 PONTIAC GRAND PRIX LE SEDAN
    <br />110k miles, 3.1 MPFI

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