Question about 2007 Chevrolet Silverado 2500HD

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The air conditioning will only work in defrost and floor mode, even if I have the mode on the panel selection.

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  • Roy Funkhouser
    Roy Funkhouser May 11, 2010

    It would help if y9ou could tell me what is the year make and model of your vehicle. This information will greatly help in the diagnosis and repair of your vehicle. Thank You, Roy


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I would say the mode door actuator is bad or the mode door is broken.
Thank You,

Posted on Aug 06, 2009

  • hende80 Jul 10, 2011

    Where is this located? Thank you!


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How do I remove the center console where the heater control switches are located on a 2006 Pt Cruiser GT

DESCRIPTION A manual temperature control (MTC) single zone type heating-A/C system or a manually controlled heater-only system is standard equipment on this model, depending on market.
To maintain the performance level of the heating, ventilation and air conditioning (HVAC) system, the engine cooling system must be properly maintained. The use of a bug screen is not recommended. Any obstructions in front of the radiator or A/C condenser will reduce the performance of the A/C and engine cooling systems.
The engine cooling system includes the radiator, thermostat, radiator hoses and the engine coolant pump. Refer to 7 - Cooling for more information before opening or attempting any service to the engine cooling system.

All vehicles are equipped with a common heater, ventilation and air conditioning (HVAC) housing (1). The heating-A/C system combines heating, ventilating and A/C (if equipped) capabilities in a single HVAC housing mounted within the passenger compartment beneath the instrument panel. The HVAC housing includes:
  1. Mode-air doors (2)
  2. A/C evaporator (A/C system only) (3)
  3. Recirculation-air door and actuator (A/C system only) (4)
  4. Blower motor (5)
  5. Mode control cable (6)
  6. Temperature control cable (7)
  7. Heater core (8)
  8. Blend-air door (9)
On heater-only systems, the A/C evaporator is omitted from the HVAC housing and is replaced with an air restrictor plate.
Based upon the system mode selected, conditioned air can exit the standard heater-only or optional heater-A/C housing through one or a combination of the three main housing outlets: defrost, panel or floor. The defrost and panel outlets are located on the top of the HVAC air distribution housing and the floor outlets are located on each side of the distribution housing. Once the conditioned air exits the HVAC housing, it is further directed through molded plastic ducts to the various outlets within the vehicle interior. These outlets and their locations are as follows:
  1. Defroster Outlet- A single large defroster outlet is located in the center of the instrument panel top cover, near the base of the windshield.
  2. Side Window Demister Outlets- There are two side window demister outlets, one is located at each outboard end of the instrument panel top cover, near the belt line at the A-pillars.
  3. Panel Outlets- There are four panel outlets in the instrument panel, one located near each outboard end of the instrument panel facing the rear of the vehicle and two located near the top of the instrument panel center bezel.
  4. Front Floor Outlets- There are two front floor outlets, one located on each side of the center tunnel near the dash panel.
  5. Rear Floor Outlets- There are two rear floor outlets, one located on each side of the floor panel center tunnel near the front of each rear seat foot well.
    WARNING: Disable the airbag system before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to follow these instructions may result in accidental airbag deployment and possible serious or fatal injury.

    NOTE: Illustration shown with instrument panel removed for clarity. (Refer to 23 - Body/Instrument Panel/BEZEL, Instrument Panel - Removal).(Refer to 24 - Heating and Air Conditioning/Controls/CONTROL, A/C and Heater - Removal).(Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Removal). 5. Remove the screw (1) that secures the temperature control cable (2) to the left side of the HVAC air distribution housing (3). 6. Disconnect the temperature control cable from the blend door pivot lever (4) and remove the cable from the vehicle.

    WARNING: Disable the airbag system before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to follow these instructions may result in accidental airbag deployment and possible serious or fatal injury. (Refer to 24 - Heating and Air Conditioning/Controls/CONTROL, A/C and Heater - Removal).(Refer to 08 - Electrical/Clock - Removal).(Refer to 08 - Electrical/Power Windows/SWITCH, Power Window - Removal).(Refer to 24 - Heating and Air Conditioning/Distribution/OUTLET, Air - Removal).

Oct 31, 2016 | Cars & Trucks

1 Answer

Heater control wont switch to the defrost

In your HVAC unit there are at least two 'doors' that are moved by servos. (1) regulates your temperature - the blend door, which adjusts/blends the amount of air coming through your heater core and your air conditioning evaporator. (2) regulates where the air goes - the mode door (there may be multiples of this depending on your model, etc), that selects floor, dash vents, and defroster vents. One of your servos may be bad, or your mode door may be jammed.

Jan 20, 2016 | 2001 Dodge Intrepid

1 Answer

The ac on my 1998 ford ranger only blows out the defrost vent and floor vent. How do I fix it?

Almost sounds like the actuators are inop. depending on which style you have, some are electrical motors and some are vacuum. These control the mode doors which move to deflect air to various vents.

Jul 03, 2012 | Ford Cars & Trucks

1 Answer

Climate Control - Heat and cool work fine. Air flow is directed to defrost /floor. No indication (Sound or sight) that the vacuum diaphrams are being activated. The display on the dash matches the...

Does your vehicle have manual or automatic climate control ? You system is stuck in floor an defrost mode ?

03 mercury grand marquis hvac air flow .-13qahwfdndst2y1hypmr2cdq-4-0.gif Item Part Number Description 1 18A318 Vacuum control motor-floor/defrost door 2 - Defrost air flow 3 18A478 Floor/defrost door 4 18476 Heater core 5 19860 Evaporator core 6 19805 Blower motor 7 - Outside air inlet 8 19A813 Air inlet door 9 18A318 Vacuum control motor-air inlet door 10 - Recirculated air inlet 11 18B545 Temperature blend door 12 18A559 Panel door 13 - Panel air flow 14 18A318 Vacuum control motor-panel door 15 - Floor air flow 16 - Vacuum from the engine intake manifold 17 19A563 A/C vacuum check valve 18 19A566 Vacuum reservoir tank and bracket 19 19980 EATC control
Pull the control panel an check for vacuum

vacuum lines hvac 03 grand marquis-13qahwfdndst2y1hypmr2cdq-4-2.gif Item Part Number Description 1 White Air inlet door 2 Yellow Floor/defrost door 3 Red Floor door 4 Blue Panel door 5 Black Source vacuum 6 - Not used

VACUUM APPLICATIONS CHART-ELECTRONIC AUTOMATIC TEMPERATURE CONTROL Switch Port Vacuum Harness Hose Color Func- tion Manual Override Selector Buttons OFF MAX A/C NORM A/C VENT FLOOR FLOOR/ DEF DEF 1 White Air inlet 2 Yellow Floor/ panel (partial) 3 Red Full floor 4 Blue Panel 5 Black

May 21, 2017 | 2003 Mercury Grand Marquis

1 Answer

Heat does not come out passenger side of the car but comes out drivers side

There is a blend door problem.

prev.gif next.gif HEATING AND AIR CONDITIONING Refer to Section 1 for discharging and charging of the air conditioning system. The heating system provides heating, ventilation and defrosting for the windshield and side windows. The heater core is a heat exchanger supplied with coolant from the engine cooling system. Temperature is controlled by the temperature valve which moves an air door that directs air flow through the heater core for more heat or bypasses the heater core for less heat. Vacuum actuators control the mode doors which direct air flow to the outlet ducts. The mode selector on the control panel directs engine vacuum to the actuators. The position of the mode doors determines whether air flows from the floor, panel, defrost or panel and defrost ducts (bi-level mode).

Oct 28, 2010 | 1998 Oldsmobile Regency

1 Answer

2004 Dodge Ram 3500 Turbo Cummins diesel, air conditioning is cold but there is very little air pressure even when turned on high, fan sounds like it is blowing like crazy but very little air movement...

Sounds like the "Blend Doors" are not completely closed (or opened). The Blend Doors open and close to direct the air from the blower motor to the vent selection you have made on the control panel (defrost on windshield, floor, front, etc) You may need to try various selections to see if the blend doors actually open or close. If no changes, it could be a blend door actuator failing.

Aug 05, 2010 | Dodge Ram 3500 Cars & Trucks

1 Answer

2003 Chevy trailblazer, the 4 front dash air

{: ) Check first the fuse labeled HVAC1 10A at the rear fuseblock. If okay, the mode actuator could be faulty. You can try this: turn ignition switch and a/c off for a minute. Then turn ignition on, wait forty seconds. Afterwards, start the engine, and check your a/c again.

Aug 01, 2010 | 2006 Chevrolet Trailblazer

1 Answer

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.

Oct 17, 2009 | 2001 Dodge Ram 1500 Truck 2WD

1 Answer

Air vents and defroster

replace the vacuum mode control switch in the heater control, this is a dealer only part.

Mar 22, 2009 | 1999 Ford Expedition

1 Answer

2007 F-150 Supercrew Lariat Cabin Air Filter

According to the shop manual you do not have one.
Air Distribution and Filtering adobe.gif Printable View (79 KB) NOTE: The air distribution system of this vehicle cannot be equipped with a cabin air filter.
There are 2 sources of air available to the air distribution system:
  • Outside air
  • Recirculated air
Recirculated air is automatically used when the electronic manual temperature control mode selector is set in the MAX A/C or OFF modes and can be selected in any mode other than MAX A/C, OFF or DEFROST by selecting the RECIRC button. Recirculated air is available in all modes except DEFROST. If the vehicle is equipped with an electronic automatic temperature control (EATC) system, recirculated air is used in OFF and is available in all modes except DEFROST. RECIRC mode is a timed function in FLOOR and FLOOR/DEFROST.
Air distribution within the vehicle is determined by the electronic manual temperature control (EMTC) function selector switch position, or is controlled by the EATC system in the AUTOMATIC mode. The air distribution mode on EATC vehicles may be overridden by the driver if desired. Air distribution doors are used to direct airflow within the heater core and evaporator core housing and the plenum chamber. An electronic mode door actuator is used to position these air distribution doors. One air inlet mode door is used to switch between FRESH or RECIRC air inlet. An electric actuator is used to position the air inlet mode door.
Air enters the passenger compartment from the:
  • instrument panel A/C registers.
  • heater outlet floor ducts.
  • windshield defroster duct.
  • side window demisters.
  • center flow-through console (if equipped).
Passenger compartment air is exhausted from the vehicle through open windows or body air vents.

Mar 08, 2009 | 2007 Ford F-150 Harley Davidson

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