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What causes my 2002 Envoy to stop running when I turn on a/c? Also defrost won't work ion dash vents

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Could be a low charge rate from alternater as a/c uses masses of power so could be enough to stop other electrical units operating

Posted on Apr 23, 2014


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Posted on Jan 02, 2017

  • 65 Answers

SOURCE: No air flow from defrost vent on my van.

Could be a vaccum line leaking not changing the vent flap to defrost

Posted on Jan 10, 2009

  • 37 Answers


Sounds like you have a supply vacuum problem. When you lose supply vacuum to the control head it defaults to defrost.

Posted on Mar 13, 2009

  • 5 Answers

SOURCE: dash vents not working

It may be the actuator not working properly. Should be above the accelerator pedal to the right.


Posted on May 20, 2009

  • 169 Answers

SOURCE: my 2002 trailblazer is making a clicking noise in the a/c

more likely a broken door in hvac case.with car running work controls and watch actuaters operate to locate good luck maybee a little challange

Posted on Aug 30, 2009

  • 4803 Answers

SOURCE: I have a 2002 Dodge Ram where vent selection won't change

Your heating and air conditioning system is controlled by the Body Control Module (BCM). Any diagnosis should begin with scanning the (BCM) for trouble codes to determine the source of the problem and/or which circuits and components are involved.

If a failed mode door actuator is, in fact the problem, the instrument panel must be removed to gain access to it.

Posted on Oct 17, 2009

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I have a 2002 GMC Envoy with auto climate control. It won't change the air from the floor to the dash vents when requested. There are times when the air will come out of the dash and the tempera

the load ratcheting sound is likely the mode door actuator. It is contains a small motor with gears that turns the mode door to the various positions. Those gears can strip and cause the noise you hear. It is fairly simple to look and feel around under the dash to locate these actuators. There are a minimum of three depending on what climate control you have. There will be one for the temperature control, one for the mode control and one for the fresh air control.

Sep 20, 2012 | 2002 GMC Envoy

3 Answers

Heater clicking noise in gmc envoy

Do you hear a clicking noise when you turn your truck on? Its probably the actuator. While the defroster was on I removed the fuse locted under the rear driver side seat. I think its 36B. It stopped the clicking noise and my air vents work well now.

Dec 08, 2011 | 2003 GMC Envoy

1 Answer

2002 GMC Envoy Blower fan seems to work fine but little air coming from the vents. It seems like the air is spread throughout all the vents including defroster. Where should I start?

The problem is most likely one or more of the mode control actuators or the doors that they drive. Sometimes the doors bind or else the actuator gears break. Unfortunately, these parts are not that easy to get to. Some of the parts can be accessed from under the dash after removing some panels, others are buried. Attached is a diagram of their locations.


Aug 07, 2011 | 2002 GMC Envoy

1 Answer

Blows air only through defrost vent no where else

i had this problem with my envoy, it an hvac mode acuator, after i replaced it works perfect, it is hard to get to tho, its up under the dash in the middle

Mar 23, 2010 | 2002 GMC Yukon XL

1 Answer

A/c heater wont blow out of dash vents only defrost vents

i had that problem with my envoy, it a hvac mode acuator,dealer said 103 i got it for 57, if your good with working on cars its not too bad of a job but the piece is hard to get to its up in the dash

Mar 17, 2010 | 2002 Chevrolet Silverado 2500HD

1 Answer

Floor vents not working in my Avalon.

When you turn the dial to the floor vents, do you hear anything. You should hear a flap or something move after the dials been turned. There's a flap (direction control) just above the blower behind the passenger side dash. This directs the air to where it's supposed to go. It sounds like yours may have come loose

Aug 18, 2009 | 2004 GMC Envoy

2 Answers

Dash vents will not blow air

It may be the mode actuator. Have you heard any clicking or other strange noise ? Under the drivers rear seat, in a plastic box is a fuse panel. Remove the two retainers, and the cover. Remove the HVAC or A/C fuse for a minute or two. Reinstall the fuse and this will make the A/C system relearn. Whwn you put the fuses back do not touch the A/C controls. Start the truck and leave it run for two or three minutes. Then try to change the vent from floor to vent and defrost. If this does not work you will need a mode motor. Good Luck

May 22, 2009 | 2006 GMC Envoy

3 Answers

Dash Vent problem

I got the same problem. I was told it was the AC control module that goes bad and it kills the ability to blow air out the AC dash vents. My Envoy is a piece of junk, electrically speaking.

Jul 16, 2008 | 2004 GMC Envoy

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