GM Truck Club
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 8 of 8

Thread: Dual Air Issue

  1. #1

    Default Dual Air Issue

    Good Morning All,

    I have a 1999 GMC K1500 with front and rear air. I had to relocate the AC compressor when I removed the intake manifold but I did not disconnect the lines. About 2 weeks after I completed the work I noticed my AC not cooling and discovered the compressor was leaking around the case joint. I was told this happens when you move the compressor as I did. I added a couple of 12 oz cans of R34 with stop leak then another 2 cans of plain R34. Now my front AC is not blowing cold but you can hang meat in the rear of the vehicle. I think the air out of the rear vents drops about 40-45 degrees. The pressure on the low side indicates 45 psi but there does not appear to be any high side pressure. I am going to check again then replace the compressor if it still shows no pressure.

    My question is why would the front be so warm and the rear so cold? They are both running off the same compressor. I am fairly new to working on AC issues so please dumb down the answers a little.

    Thank you,

  2. #2


    Did you check the AC lines and make sure there aren't any leaks in the lines going to the front vents?
    04 ECSB Custom silver & grey, Soft 8's, BFG KO's, ReadyLift Leveling Kit, Hellwig front sway bar, K&N filter, DeeZee EZ-Down, Rhino liner, Alpine CDE103BT, Rockford 6.5's, 12" V.A.T. Hammer Pro in a Subthump box, Alpine PowerPack amp, Hifonics amp, BackRack w/ 55w 5000k HID KC Daylighters, KC light bar with 4 KC Slimlites, UWS toolbox, Shaved Antenna mod, Black Bowtie, LED backup, license plate, dome lights & 3rd brake light

  3. #3


    I am getting air out of the vents it is just not cold, just a cooler than outside air by about 10 degrees.

  4. #4
    Sr. Engineer
    Join Date
    Aug 2009
    Virginia Beach, VA.


    Your air blend door stuck to the warm side maybe??

  5. #5


    I have tried the thermostat on the dash, I can adjust it from cool to hot and it will start blowing hot. That tells me it is not the dash thermostat.

    Could it be a switch on the AC system somewhere causing it not to send coolant to the forward condenser? The rear condenser drips rather profusely but the forward almost doesn't drip at all.

    Under the hood next to the compressor are two large metal cans, they actually look like soup cans. One is really hot, I think that is off the high side, the other is cool but not cold. My neighbor has a 1999 Tahoe and his are wet with condensation. Mine does not do that.

    Hope that helps.

  6. #6


    X2 on the blend door. If it is working for the back like it should and not the front. It is a common system meaning the "conditioning" for front and back is done with the same components.

  7. #7
    Caddiac's Avatar
    Join Date
    May 2011
    Upstate South Carolina
    Blog Entries


    I had the same problem with my 98 only the compressor was never touched. It turned out that it was low on refer because of a fitting on the compressor leaking. You might just still be low on refer.

  8. #8


    Does your system have 2 evaperators?

Similar Threads

  1. Installed Flowmaster super 40 series dual in / dual out
    By Rockstarrchevy81 in forum Chevy Truck Accessories
    Replies: 2
    Last: 05-10-2011, 08:10 PM
  2. Flowmaster 40 Series dual in/ dual out
    By Rockstarrchevy81 in forum Chevy Truck Accessories
    Replies: 3
    Last: 05-08-2011, 12:02 AM
  3. Dual alternators and dual batteries
    By Jamie99 in forum GM Electrical Tech
    Replies: 11
    Last: 02-17-2011, 05:42 PM
  4. '96 dual fuel tank issue
    By zebra308 in forum GM Powertrain
    Replies: 13
    Last: 12-22-2010, 05:34 PM
  5. dual side or dual rear
    By drwdominance in forum Performance & Fuel
    Replies: 10
    Last: 04-11-2010, 10:42 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts