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1996 Suburban AC Problems

Discussion in 'General Chevy & GM Tech Questions' started by bigbob94, May 9, 2008.

  1. bigbob94

    bigbob94 New Member

    Before I tell you my problem let me first say thanks to all you folks for monitoriing this forum and offering for free your expert advice. I'm a pastor and can't afford new cars so I've go to be able to repair and keep my machines running. Thanks!

    I have a 1996 Chev Suburban 4x4 350. Last summer the AC stopped blowing cold air. Everything works fine just warm air instead of cold air.

    So this week I went and got a recharge kit. I turned on the burb, turned on the AC connected the refrigerant (following the directions) can with pressure guage. The pressure was low--less than 10 psi. So I shot some into the system until it reach about 35psi. Then the compressor turned on (or engaged). Yikes, the pressure dropped back to 10. The compressor disengaged. The pressure went back up to 35psi. Back and forth every 5 seconds. (I think they call this short cycling). So, I thought the system needed more R-134A so I took the pressure up the 45psi. Then the compressor would engaged and drop down to about 20ps. I drove it around no cold air. The compressor would just go on and off.

    The problem is that I cannot add more A-134A because I'm at 45psi and that is in the Yellow on the gauge that says "Alert" don't add more refrigerant.

    So now what? do I have a bad compressor? How to I get the compressor to stay engaged so the refrigerant will cycle through and equalize the pressure.

    Any help or thoughts would be appreciated.

    Robert (bigbob94)
  2. Crawdaddy

    Crawdaddy Epic Member Staff Member 5+ Years 1000 Posts Platinum Contributor

    It's all a matter of playing the waiting game. When you put refigerant in, you're putting it in on the low side. When the compressor kicks in, it starts circulating it, and the low side gets low on the pressure again. When the compressor kicks out, the pressure should rise back up. If the pressure when the compressor kicks out is ok, let it sit for a while. It'll slowly kick in and out, pulling more refigerant onto the high side. Keep adding more till you get to the reccomended pressure when the compressor is kicked in. Also, make sure the fan is on high, ac switch it, and either recirc is on, or max air is on (whichever the vehicle is equipped with). I apologize if the directions are a little fuzzy, I have a diffcult time describing processes like this... I also invite everyone else to fact check me on this...
  3. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Crawdaddy is rihgt on. The pressures need to be checked with the engine running and the compressor clutch engaged. The Suburban has a big system, so it may take a bit of freon to get it back up to proper levels.
  4. LANDBARG

    LANDBARG Rockstar

    Also, with it running, make sure the receiver/dryer, the metal cannister looking thing by the passenger firewall, starts to sweat. If not, you have a clog somewhere, most likely in the expansion valve or evaporator coil.
    Last edited: May 12, 2008
  5. collinsperformance

    collinsperformance Epic Member 5+ Years 500 Posts

    pne more note-------over charging R-134A will reduce the cooling properties so let it balence a couple days and recheck. is it blowing any colder? it should be and the compressor likes to run arounf 1400+ RPM.....mike

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