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How to reset the HVAC mode actuator,becaoused my dash vents seem no airflow coming out.

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  • Paul Marshall
    Paul Marshall Apr 06, 2009

    No air coming out of the dash vents, only the defrost and floor. There was a clicking noise before it quit all together. Could it be the HVAC mode actuator?

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  • Chevrolet Master
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You have a problem with mode mode control switch, it is either leaking vacuum or has no vacuum to it, all of the different modes are switched using vacuum operated air door motors to send air to the selected outlet, i.e. floor, dash. defrost or a mix.

Posted on Oct 17, 2008

  • yadayada
    yadayada Oct 20, 2008

    This rating is unjust based on your question and my 30 years of automotive experience the answer is correct. What answer did you want, there is flat no such thing as a HVAC reset, please change the rating to a more appropriate Helpful.

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My 2002 Cadillac Deville won't blow air directly to my face out of the vents, please help.


Center vents not working , is this what your saying ? Air comes out of the defroster vent or floor vent only ? Mode door stuck or mode door actuator bad !
Mode and Recirculation Actuators The mode and recirculation actuators are 2-wire bi-directional electric motors. Two control circuits enable the actuators to operate. The control circuits use either a 0 or 12 volt value to co-ordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 12 volts. In order to move the actuator, the HVAC control module grounds the appropriate control circuit for the commanded direction. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
The HVAC control module(IPM) determines the door position by counting motor pulses on one of the control circuits. These pulses are small voltage fluctuations that occur when the brush is shorted across two commutator contacts as the motor rotates. As the actuator shaft rotates, the HVAC control module(IPM) monitors the voltage drop across an internal resistance to detect the pulses. The HVAC control module(IPM) converts the pulses to counts with a range of 0-255 counts. The HVAC control module(IPM) uses a range of 0-255 counts to index the actuator position.
If the problem is the actuator the instrument panel has to be removed to replace it . Your best bet is to take your vehicle to a qualified repair shop .

Jun 28, 2016 | Cadillac Cars & Trucks

1 Answer

My heater is stuck on the windshield and floor what actuator needs to be changed


Air Distribution
The HVAC control module controls the distribution of air by the use of a defrost actuator and a mode actuator. The modes that may be selected are:
?€¢
Defrost


?€¢
Defog


?€¢
Panel


?€¢
Bi-Level


?€¢
Floor

The mode and defrost actuators are connected to the mode and defrost doors by a cam type linkage system. Depending on the position of the door, air is directed through the HVAC module and distributed through various ducts leading to the outlets in the dash. If the HVAC control module detects a fault with the mode or defrost doors the HVAC control module will try to drive the actuator for a predetermined amount of time, to defrost, which is the defaulted position for the mode and defrost door actuators. When the mode switch is placed in the defrost or defog positions the A/C is commanded on and the recirculation door is moved to the outside air position to help reduce window fogging. A/C is available in all modes and recirculation is only available in the panel and bi-level modes.
Circuit Description The following DTCs are for the HVAC door actuators: ?€¢
B0248 is for the defrost actuator.
?€¢
B0263 is for the mode actuator.
?€¢
B0408 is for the left air temperature actuator.
?€¢
B0418 is for the right air temperature actuator.
The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The logic circuit inside the actuators receives control signals from the HVAC control module and controls the internal stepper motor. When a door positional change is required, the HVAC control module calculates a commanded door position. The module compares the commanded door position to the actual door position and determines the needed direction of motor rotation. The module applies a signal voltage to the door control circuit that is an input to the internal logic circuit of the door actuator. A 5 volt signal increases the door position. A 0 volt signal decreases the door position. When the commanded door position is equal to the actual door position, the HVAC control module sends a 2.5 volt signal to the door actuator and motor rotation stops. The ignition 3 voltage circuit provides source voltage to the logic circuit. The module provides ground to the actuator logic circuit through the low reference circuit. I would start by having the HVAC control module checked for DTC'S -diagnostic trouble codes First . Then check the system by using scan tool data . 1
Did you perform the HVAC Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - HVAC Systems - Manual

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the appropriate HVAC door actuator ON and OFF while observing the corresponding Door Actual parameter.
Does the scan tool indicate that the value of the appropriate Door Actual parameter changes?
Go to Diagnostic Aids
Go to Step 3

I would

Apr 02, 2016 | 2003 Chevrolet TrailBlazer

1 Answer

The air only comes out of the circle vents on dash, not the defroster vents or floor vents. I have a 2005 Pontiac G6 base model and I am not sure how to fix this issue


In side you dash is a electronically controlled actuator call a mode actuator , it controls which vents the air comes out of ! They go bad, plastic gears in side of it wear out, a lot of times you'll hear a clicking sound in the dash. They are not to tough to fix ,you need to take Instrument Panel Insulator Panel off - Left Side under dash . Some times stuff drops down in an binds up the door inside .Have a little child , they like putting stuff in the vents ,pencil's an the like.
Mode Door Actuator Dorman 604 121 Controls Airflow Direction

Jan 10, 2015 | 2005 Pontiac G6

1 Answer

MY 2005 FORD MUSTANG V-6 THE AC ONLY BLOWS THRU THE DEFROST VENTS ?


  • Do you hear any clicking noise form in the dash ? Sounds like the mode door actuator mite be bad or stuck or the HVAC control module isn't controlling it. The ford service repair information manual has a long drawn out test procedure PINPOINT TEST B: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S) You would have to take some of your dash apart to get at the wiring connectors on the back of the HVAC control module . You need a volt- ohm -meter to do some testing : first thing is to
  • Dec 20, 2014 | 2005 Ford Mustang V6

    1 Answer

    No air coming out the dash vents. Air does come out the floor vents and defroster vents


    {: ) You didn't mention which vehicle model you have, but anyway, check and make sure your control setting is not on defog or defrost. When the HVAC system detects a fault or inconsistencies in the actuator feedback circuits, the HVAC module will default the position of the mode actuator to the floor vents. Usually the fault is caused by the mode actuator itself, or it could be that the actuator doors are blocked or binding, and wiring or terminal connections come next on the list.
    If it is an actuator door issue, the HVAC Blower Module should be removed and disassembled. And this also means removing the whole instrument panel which is a big job. I just hope your case doesn't go this far.
    For the meantime, what you can try is to recalibrate the actuators. Turn a/c and ignition off. Turn ignition on and wait forty seconds ( don't move any HVAC controls during this period). Afterwards, you may start the engine and check operation. If not successful, a scan tool is the next option, to retrieve any codes set, and to perform actuator recalibration.

    Jul 15, 2011 | Chevrolet Silverado 1500 Cars & Trucks

    2 Answers

    I changed the battery on 2006 Trailblazer SS. Now I can only get AC from my windshield and floor vents. Nothing from the dash vents. Also the temp control only gives coldest temp. I have checked fuses...


    once you disconnect the battery your body control module loses power and memory you have to get some one with a scanner with reprogramming capabilities and have the computers reset ,dealer?

    Aug 05, 2010 | Chevrolet TrailBlazer Cars & Trucks

    1 Answer

    2006 slt gmc envoy ac problems vent controls anbd


    {: ) The popping sound you heard is caused by the sudden movement of an HVAC door, most probably coming from the recirculation door actuator (right dashboard area) or the mode actuator( mid dashboard area). The fan outputs could be normally working, but is being muffled by the incorrect positioning of the HVAC doors, giving an impression that there is fault in the blower controls. In other words, your vehicle is having an air distribution issue.
    If there's no conflict in your climate settings, then the trouble may be in the HVAC doors binding or broken, or the actuators faulty or sticking. In both cases, servicing may involve removal of the dashboard to access these HVAC components.

    Jul 20, 2010 | 2006 GMC Envoy

    1 Answer

    Location and removal of the air vent actuator. step by step on how to get to it and replace it. Air blows and I can control hot and cold but I cant change from floor to vent to dash. It just keeps blowing...


    Removal & Installation
    1. Remove the floor air outlet duct extension from the floor duct.
    2. Remove the center console, if equipped.
    3. Remove the screws from the center console duct, if equipped.
    4. Remove the center console duct, if equipped.
    5. Disconnect the electrical connection at the mode actuator.
    6. Remove the mode actuator mounting screws from the HVAC module.
    7. Remove the mode actuator as an assembly with the actuator cam.

    98d9332.gif
    Mode actuator location

    To install:
    1. Install the mode actuator as an assembly with the actuator cam.
    2. Line up the heater/defroster valve lever with the mode actuator cam slot.
    3. Line up the A/C valve lever with the mode actuator cam.
    4. Install the mode actuator mounting screw to the HVAC module and tighten to 14 inch lbs. (1.6 Nm).
    5. Connect the electrical connection at the mode actuator.
    6. Install the center console duct, if equipped.
    7. Install the screws to the center console duct, if equipped, and tighten to 14 inch lbs. (1.6 Nm).
    8. Install the center console, if equipped.
    9. Install the floor air outlet duct extension to the floor air duct.
    10. Calibrate the HVAC module actuators.

    Apr 18, 2010 | 2004 Chevrolet Tahoe

    1 Answer

    AIR VENT PROBLEM


    Chevrolet 2003 TrailBlazer

    For a digital air flow system try resetting the HVAC unit. Either take out the fuse for the HVAC module or disconnect the battery for 5 or 10 minutes. Reconnect battery or replace fuse. Turn the ignition to ON and DO NOT STARTor ATTEMPT to START ENGINE !!. You should hear the actuators, motors etc resetting. This should take about 2 minutes . Then you can start engine. If this does not work, you may have a bad actuator under the dash.

    Jun 07, 2009 | 2003 Chevrolet TrailBlazer

    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

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