Suddenly HOT air from vents!!!!????

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Hwy St*r, May 23, 2012.

  1. Hwy St*r

    Hwy St*r Member

    Ok fairly pleasant NJ morning today I'm about 30 minutes into my 45 minute commute have the fan on with temp setting all the way down with the direction set to dash vents to bring in some cool fresh air when suddenly HOT air start coming from the the vents as if the temp controls have been pushed up to the very top!? No adjustments or turning off of fan, switching to air conditioning change the the temp from being HOT. Check gauges not overheating or anything else out of the norm. Get to work shut off truck, wait a few minutes and restart and now I'm back to getting cool air out of the vents. Never had anything like this happen before so would appreciate any suggestions of where to start to look.

    2005 1500 W/T V6-5speed Silverado.

    In the meantime I'll try to keep my cool!
    Thanx in advance for any & all help.
  2. Sierraowner5.3

    Sierraowner5.3 Epic Member 5+ Years 1000 Posts

    sounds like the AC condensor froze up. it happens. letting em thaw out and then trying again is usually all you can do.

  3. Hwy St*r

    Hwy St*r Member

    thought that would only happen if AC was on? I just had fan on to vent outside fresh air....
  4. RAMwoodworks

    RAMwoodworks Member

    I have an '06 and sometimes have problems when going from hot to cold or cold to hot. Seems like it doesn't always completely close or open. I have found that if I turn on the recirculate for a minute it helps with the temp doors.

    Not the same problem as yours but turning the recirculate on may help.

    I like the old days with the cables and or vacuum actuators much better. Easy to diagnose and usually cheap to fix.
  5. Hwy St*r

    Hwy St*r Member

    actually tried that too, didn't work :(

    the only thing that did work was shutting off the truck completely and upon re-starting it was like it should be.

    odd thing to me is that the air temp coming from the vents changed from cool (outside temp of fresh air) to hot without me touching any of the controls.

    one of the strangest things I've seen and yes I agree give a simpler older truck and I'd be happier.
  6. paracutin

    paracutin Rockstar 100 Posts

    Same thing has happened to me a few times in the past. Usually just the passengers side. Only way to fix it was to do just what you did and shut the truck off. However, there was a thread about calibrating the HVAC module actuators. Here it is. Fifth post down - Alternate Method (w/o Scan Tool).

    ​After doing this I have not had the problem come up again.
  7. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

  8. Jimmeh

    Jimmeh Epic Member 5+ Years 500 Posts

    My truck did the exact same thing (blew hot air with AC on, once I shut the truck off and turned back on, it worked fine), and a couple of days later, the whole HVAC system completely stopped working. GM has a recall out on the HVAC systems for our trucks that are manually operated (IE: not the ones commonly found in the LTZ trucks with the digital temp read out) to replace the resistor for the controller. My dealer had it done in an hour.
  9. Coach24

    Coach24 Rockstar 3 Years 5000 Posts

    Way to go Jimmer
  10. RobertSwindall

    RobertSwindall New Member

    My 2003 silverado does the same thing. Only fix I have found is stop, shut off engine & re-start. Usually works. Highly inconvenient though. I do have a blend door actuator problem that I am in process of fixing. Will post after that & let you know if that fixes it.

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