Fixed Heat, Now for the A/C

Discussion in 'General Chevy & GM Tech Questions' started by sje0123, Apr 24, 2010.

  1. sje0123

    sje0123 Member

    Did a full Cooling system flush today and swich out the thermostat. The rubber ring was broken allowing it to constantly flow making me have no heat. Now I need to work on the A/C.

    I'm pretty sure it's either the control knobs, or whatever inside makes it switch from Heat to Cold. There is no sound of a changeover when turning the knob.

    Anyone had this issue, or know how these systems work so I know what parts to look at to narrow it down?
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    year make model.. motor would be good.. since they all use differnt relays etc..
  3. sje0123

    sje0123 Member

    Duh, sorry about that.

    2001 Silverado 1500 Z71
  4. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    When you hit the A/C switch does it light up??? IF so is the A/C clutch engaging?? If not you need to put a jumper into the Low pressure switch and see if the clutch engages then.. If it does then you need to see how much of a chage is in your A/C system.. If the charge is 35-40 PSI with the A/C on max with the fan on High. Then you know that you have a bad low pressure switch if not then you need to put a charge into the system and find any leaks that you might have. 99% of the time that dash switches are not the culprit. Also you may want to check your A/C fuses, and Relays mounted on the fuse panel and under hood.
  5. sje0123

    sje0123 Member

    Thanks for the advice. I'll give all of that a look over this week and update.
  6. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    sounds good
  7. sje0123

    sje0123 Member

    Ok. I've narrowed it down. It nothing with anything outside of the cabin.

    If I turn the truck on with it set to cold the A/C works. Once I turn the knob to heat it will not go back to A/C unless the truck is turned off. Once it it turned off then turned to cold and the truck is started I can hear the door changing positions.

    Any ideas?
  8. Viper

    Viper Rockstar 100 Posts

    unfortunatly sounds like an electrical problem, or there is a good chance there is a leak on the vac line that operates the door for change over from heat - A/C
  9. mmorgan1865

    mmorgan1865 Rockstar 4 Years 1000 Posts

    Might be the bypass damper connection or motor. If you have to take it all apart to get to them I would suggest you change both.
  10. sje0123

    sje0123 Member

    Well if any of this is going to require pulling the whole dash I'm not even going to bother. If I need to change from heat to A/C I'll just turn the truck off. This is just a second vehicle for hauling things around and yard work. Not worth the trouble.

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