Question about 2004 Chevrolet Cavalier

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HVAC Control Head Mode Dial

The head mode dial wont switch to defrost it stays on vents and I need to get it fixed before snow seasion starts up the heater and a/c works just fine it self but can't switch modes. I researched some information and want to start with something simple and found out that I may want to replace the foam for the mode dial but I am not to sure were it is located at on my 04 cavalier. Then also the part# I would need to get.

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  • johnu220 Oct 20, 2008

    do you know how to remove the dashboard face plate to get to the guts of the hvac controls?

  • cjcarpenter Oct 28, 2008

    I had the same problem you could move the dial but it wouldn't move the air to a different location. My husband had to take the front dash all apart and replace a $12.00 cable that actually moves the door to let the air through. If you call your local dealership they should be able to get it for you.

  • b_hemenway Nov 12, 2008

    Just need something that could show me how to remove the Hvac unit or take the dash plate off so I could get to the hvac unit.



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It is an entirely mechanical process. As one user put before, you cable is kinked. I have the same problem. The way I see it is that there are 2 options. The first being replace the cable, which I have read will cost you about $90, or $12 plus pulling your dash apart. If you look under your dash, right above your accelerator, there is a wheel type thing that needs to be rotated. If you take a screw driver and push on this and turn the knob at the same time you can shift into the defroster.

Posted on Nov 22, 2008


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Selector for air mode stuck on defrost

This is caused by a low engine vacuum, the engine vacuum is low when you accelerate, the HVAC system loses vacuum to the mode control vacuum switch and defaults to the defrost ducts for safety. You likely have a leaking mode control vacuum switch in the control panel of the heater AC system (HVAC).

Jun 16, 2016 | 2001 Ford Windstar

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I have a 2006 Pontiac g6 gt and my heat or air will not turn on or rear defrost

You have a computer controlled HVAC system ! It has the capability of setting DTC'S - diagnostic trouble codes !
The HVAC control module is a non-GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive and ignition 3 voltage circuits provide power to the control module. The HVAC control module during defrost mode will change the A/C compressor LED status from on to off. The control head displays recirc, outside air, A/C and rear defrost feedback status through LED indicators. The control head has a rear defrost request switch please refer to Rear Window Defogger Description and Operation in Stationary Windows for operation. The HVAC control head will display NO COMMUNICATION when checking DTCs or doing a vehicle diagnostic system check refer to Diagnostic Trouble Code (DTC) List - Vehicle and Diagnostic System Check - Vehicle in Vehicle DTC Information.
The rear window defogger system consists of the following components:
Body control module (BCM)

Heating, ventilation, and air conditioning (HVAC) control module

Rear Defog relay

Rear window defogger grid

Your probably better off taking this to a ASE certified repair facility ! You probably have bad Heater / A/C control panel . HVAC Control Module Malfunction

May 06, 2015 | Pontiac Cars & Trucks

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My heat on blows from the defrost how do i fix?

The heat/vent blend door that is located inside of the HVAC system behind dash..Rarely it is the control however it could be....Some of the vent door issues are recalls on certain vehicles."Also Blend vent door actuators that operate the doors can become inoperable...If it is the door inside the HVAC it will probably take about 8 hours to repair...Most vent doors either stick shut and or well as actuators....Only a Dealer Scanner can tell exactly where the problem is.....

Feb 22, 2015 | 2008 Jeep Liberty

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My ac and heater are stuck in defrost and i cant figure out why i turn the dial to vents and heat but it stays in defrost

It all depends on whether your truck is equipped with Automatic Climate Control or Manual HVAC. You could have a broken control head assembly a broken mode door cable, a failed electronic mode door actuator, a broken mode door, or a loose or broken wire or connector.

To put it simply, your mode doors are not swithching modes - the reason for this can vary depending on which system you have.

Nov 14, 2011 | 1999 Chevrolet Silverado 1500

1 Answer

Had the battery changed, but now the (heat) vents in the top of the van and the floor vent (heat) does not work - only cold air comes out. Also, the heating/cooling dial lets it get hot midway on cold...

Try this calibration procedure and let us know if you have more questions:
  1. Start the vehicle.
  2. Wait 40 seconds for the HVAC control module to self-calibrate.
  3. Verify that no DTCs have set as current DTCs.
  4. Clear all DTCs.
  5. Place the ignition switch to the OFF position.
  6. With the Mode knob in the PANEL position, press and hold the AC button for 5 seconds.
  7. Rotate the Mode knob fully counterclockwise.
  8. Rotate the Mode knob fully clockwise.
  9. Rotate the Mode knob fully counterclockwise.
  10. Release the AC button.
  11. Wait 40 seconds for the HVAC control module to self-calibrate.
  12. Start the vehicle.
  13. Verify that no DTCs have set as current DTCs.

Nov 14, 2010 | 2005 Pontiac Montana SV6

1 Answer

Climate controls wont change from vents to defrost

There may be a problem in the climate control head. The most common problem with HVAC systems of that error is a broken vacuum line. Usually the feed line to the control panel is broken or disconnected from the engine and it is stuck in defrost mode as it's the default mode. If your stuck in the vent mode there may be a broken line at the climate control panel, a broken line to an actuator or a bad actuator.

Jan 02, 2010 | 1989 Pontiac Grand Am

2 Answers

How or what do I have to do to get the air to blow through the ac vents ? It only blows through the defroster...

Hello nuttierthenu...Chrysler issued a TSB (technical service bulletin) on this problem to correct the issues it was having on the Stratus and the Cirrus.....
The mode door actuator, located in the A/C-Heater housing, is controlled by the Body Control Module (BCM) . When the operator requests a mode of operation, the BCM processes the signal from the control head and actuates the mode door to the proper position. 62486887.gif
The good thing is the Body Control Module (BCM) will store a DTC for this system but the bad thing is you need the Chrysler DRB scan tool to get them.
There is a TSB out on this problem.
TSB NO: 24-12-95
GROUP: Heater & A/C
DATE: Aug. 18, 1995
HVAC System Stuck in Defrost Mode
1995 (JA) Cirrus/Stratus
HVAC system stuck in defrost mode. May be intermittent.
Check Diagnostic Trouble Codes (DTC's) in the Body Control Module (BCM). If no DTC's exist and vehicle is no longer stuck in defrost, perform all steps in the repair procedure (Steps 1 through 5).
For a "HVAC Mode Door Feedback Failure", proceed to step # 1.
For a "HVAC Control Head Input Shorted To Ground/Shorted To Battery", refer to the 1995 Cirrus/Stratus Body Diagnostic Procedure Manual (Publication No. 81-699-94029), Section 7.0, "Manual A/C System".
PARTS REQUIRED: AR 4864052 Wiring Connector Repair Kit, Mode Actuator Connector AR 4644834 Actuator, HVAC Mode AR 4856997 Body Control Module, Vendor Part, Order on DIAL Function 11 AR 4864311 Wiring Connector Repair Kit, HVAC Control Head Connector REPAIR PROCEDURE:
This bulletin involves testing and replacing the HVAC Mode Actuator/Connector, Control Head Connector, or Body Control Module as necessary.
  1. Check Mode Actuator connector (C215) for full insertion/locking into Mode Actuator and spread terminals. Repair as necessary. The terminals in question are referenced on Page 8W-80-27 of the 1995 JA Service Manual (Publication No. 81-270-5121). In connector C215 check cavities #2 through #4. A visual check is not sufficient. A .0044" pin gauge is required. Repair any spread terminals with wiring connector repair kit P/N 4864052. Replace HVAC Mode Actuator P/N 4644834.
  2. Check BCM P/N. If it is not P/N 4856997, replace. Proceed to step # 4.
  3. Check HVAC Control Head connector (C204) for full insertion/locking into Control Head and for spread terminals. Repair as necessary. The terminals in question are referenced on Page 8W-80-23 of the 1995 JA Service Manual (Publication No. 81-270-5121). In connector C204 check cavities #5 and #8. A .0040" pin gauge is required. Repair any spread terminals with wiring connector repair kit P/N 4864311.
  4. Check battery voltage. If not above 11.5 volts, charge battery. Check for charging system problems. Perform "On Vehicle Battery Test Procedures" as outlined in section 8A of the 1995 JA Service Manual.
  5. Assure ignition is off and key is out. Pull IOD fuse (10A, cavity #5 in Junction Block). Do not replace for a least 1 minute. This will clear all BCM faults and cause the HVAC to re-calibrate when ignition is turned to the "RUN" position.
There it is...Good luck...hope this helps, please rate me a fixya

Jul 24, 2009 | 1995 Chrysler Cirrus

1 Answer

Heater works ok but wont send air thru defrost vents

check the control knob it may appear to be working but is not turning the actual controller

Jan 01, 2009 | 1995 Pontiac Grand Am

1 Answer

Grand am heater works ok but wont defrost

check cable behind dials rod most likely off on that dial.

Jan 01, 2009 | 1994 Pontiac Grand Am

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HVAC duct

This is caused by a loose of vacuum to the mode control switch, the vacuum line runs through the firewall on the passenger side near the kick pad trim.

Oct 09, 2008 | 2003 Chevrolet Cavalier

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