Hello group. My hvac controller fan switch only works on one speed and GM no longer stocks them. There is no after market part either. Any suggestions? Seriously thinking about selling the car. Thanks I did use the search.

 

ebay has them....also local salvage yards may have them too...Occasionally they pop up here as well and I think there are refurbished ones too...

 

You might do some research OP. In less sophisticated cars the fan speed is controlled by a resistor. When it fails the fan will only work on full speed. It's possible that the hvac controller still has a separate resistor. I don't know just saying it might not be the controller.

Or the resistor could be built into the controller... At which point your doinked.

 

Did a quick search. It's possible you need the blower it's self. There is some "module" on the blower. My search was far from exhaustive so I'm just spit balling here. Take my advice for what you paid for it...

 

Looks like it is all controlled within the AC controller. Another option is to take unit in to electronics shop to see if it can be refurbished.

Air Speed
The blower motor forces air throughout the vehicles interior. The vehicle operator determines the blower motor's speed by toggling the blower motor switch manually or by using the automatic mode. The blower motor will always operate at some speed as long as the HVAC control module is in any position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module.

Power is provided to the blower motor from the blower motor control processor through the blower motor supply voltage circuit. The blower motor control processor receives power from the under hood electrical center through the battery positive voltage circuit. Ground is provided by the blower motor control processor and ground circuit.

When any blower speed is selected, whether manual or automatic, the blower motor control processor will control blower motor speeds based on a 5 volt signal circuit that is pulse width modulated (PWM) signal by the HVAC control module. When a low blower speed is requested, the PWM signal is reduced. When a higher blower speed is requested, the PWM signal is increased. The blower motor control processor interprets the PWM signal and varies the ground on the blower motor control circuit internally. An open circuit, short to ground or short to battery on the blower motor speed control circuit will disrupt the PWM signal and cause the blower motor to not operate. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature. Toggling the blower button manually also activates the LCD display for the blower speed selected.

Off Mode
When the vehicle is moving, air flowing over the vehicle increases the air pressure just ahead of the windshield. This forces air into the outside air inlet, into the HVAC module and out through the floor outlets. The HVAC control module attempts to match the inside air temperature and driver selected temperatures. Since the A/C compressor is not running, the incoming air may be warmed but not cooled. Press the driver side air temperature switch to turn off the HVAC system. The ambient air temperature will show on the display.

Recirculation Mode
When the recirculation switch is pressed, the HVAC control module will apply a ground to one of the recirculation door control circuits in order to obtain the desired position. The recirculation actuator is a reverse polarity motor, each circuit provides both power and ground to the recirculation actuator. When the actuator is being held in a stationary position, both of the recirculation door control circuits have 12 volts applied to both sides of the actuator motor. This holds the actuator stationary. When a recirculate position is requested, one of the recirculation door control circuits will ground driving the recirculation actuator into the desired position. When an outside air position is requested, the other recirculation door control circuit will ground. This moves the recirculation actuator into an outside air position. This brings air from outside the vehicle instead of air from the inside.

The HVAC control module provides power and ground to the recirculation actuator. The HVAC control module receives power from the under hood electrical center through the ignition 3 voltage circuit. Ground is provided by the ground circuit.

The recirculation mode can be used in both automatic and manual operation. The only time recirculation is not available is when FRONT DEFROST and mix blend mode is selected. The RECIRC LED will flash to alert the driver that recirculation mode is not available. Pressing the recirculation switch, from the OFF position, will set the blower, mode and A/C compressor clutch into automatic mode.

When in automatic mode, recirculation will stay on until either the vehicle operator selects outside air, by pressing the RECIRCULATION switch, or the HVAC control module automatically moves the recirculation actuator. Automatic recirculation is only available when air temperatures are 21°C (70°F) or warmer. The recirculation actuator position will vary to obtain a cooler duct air temperature when cool air is selected. This will assist in cooling the vehicle quicker.

The HVAC control module will move the recirculation actuator to the outside air position at ignition off to bring fresh air to replace stale air that has accumulated in the HVAC module during shut down.

When requested the recirculation actuator will be able to move to the 100% recirculation position for a limited time, after that limited time the actuator will move to the 90% position. In the auto mode only, the recirculation actuator will move faster to the recirculation position when vehicle is at an idle compared to the normal speed of the actuator during normal operation.

If the recirculation actuator or related circuits has a failure the HVAC control module will attempt to drive the actuator to the outside air position regardless of mode selection. If there is a failure with one of the air temperature actuators the HVAC control module will allow the recirculation actuator to move to the outside air position.

Automatic Modes
The automatic HVAC system will warm up/cool down and maintain the interior temperature of the vehicle by controlling the A/C compressor clutch, blower motor, air temperature, mode and recirculation actuators to achieve the desired temperature. For fully automatic operation, both the blower and mode buttons must be in the AUTO position. Blower speeds will change automatically based on inputs to the HVAC control module . The HVAC control module will always come back to the last settings after an ignition cycle or, if equipped, to the last settings of the driver by pressing the UNLOCK button on the remote keyless entry fob and placing the ignition in RUN. Only RECIRCULATION will have to be reset after each ignition cycle.

Moisture tends to accumulate in the HVAC module assembly after the engine has been shut off. The HVAC control module will purge the HVAC module of stale air and moisture to prevent window fogging. The mode actuator will move to the floor mode and run the low speed blower for 10 seconds to purge out the air and moisture. The recirculation actuator will be in the outside air position. Purge mode can be bypassed if any manual modes are selected.

In cold temperatures, the automatic HVAC system will provide heat in the most efficient manner. On cold engine start-up, when temperatures are -1°C (30°F) or colder, low blower speeds will be selected and airflow will be directed on the windshield for 3 minutes. This is done to prevent windshield fogging. To warm the interior quickly, maximum heat mode is used where the blower is at maximum speed, floor mode, both air temperature actuators are in full hot position and outside air is being drawn in. The vehicle operator can select the extreme warm setting of 32°C (90°F), but the system will be out of automatic operation and not warm the vehicle any faster or regulate the blower speed. Once the desired temperature is reached, the blower motor, mode, recirculation and temperature will be adjusted automatically by the HVAC control module.

In warm temperatures, the automatic HVAC system will provide A/C in the most efficient manner. On vehicle start up, the HVAC control module will monitor for conditions that indicate the possible presence of moisture in the HVAC module. To avoid blowing hot air and moisture out at the driver, the HVAC control module moves the mode door toward the floor and runs the low speed blower for a 3 seconds. This purge mode can be bypassed if the vehicle is started with the blower switch in maximum speed position. To cool the interior quickly, maximum cool mode is used where the blower is at maximum speed, both air temperature actuators are in full cold position and the recirculation actuator is drawing air from inside the vehicle. The vehicle operator can select the extreme cool setting of 16°C (60°F), but the system will be out of automatic operation and not cool the vehicle any faster or regulate the blower speed. Once the desired temperature is reached, the blower motor, mode, recirculation and temperature will be adjusted automatically by the HVAC control module.

 

Thank you. I will be checking around.

 

The GM Technician said it was the hvac controller.

 

I have one out of my 06. couple of the buttons are worn but it worked when I took it out. You can have it for free. It might get you by till you find a perfect one. Can send photo by I phone. PM me your phone number and will send a photo.

 

Thank you.