I have an 03 Trailblazer and the blower motor only runs on the lowerst speed. I swiched out the blower motor control module and everything was fine for 3 or 4 days and then it would only work on the lowest speed again. I tried jiggling the wires and unplugged and reconnected the plug that connects to the module with no luck. 2 days later everything started working properly. I drove the vehicle 40 minutes to work yesterday and everything was fine but it was not working for the ride home. Someone checked the connector at the blower module and said everything looked fine and they also checked the connector that plugs into the blower motor itself as well as the connector pins on the blower motor and said what they could tell was everything was okay. It was dark out so I don't know what thet actually saw or didn't see. Can anyone help as it's getting cold out. Thanks in advance for any help offered.
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What are you using to test this control signal ? Were you on right wire ?
Blower Motor Control Processor
The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.
Chevy Trailblazer EXT Blower Motor Won Turn Off The blower motor in this video don't shut off , but he show's how to test the PWM signal right !
Your blower motor control module is probably bad , or HVAC control panel is bad , or a wiring problem !
? 3:03 www.youtube.com/watch?v=frZl49p2quk Sep 5, 2007 - Uploaded by volvoproject
All how to replace blower motor in volvo s70 v70 c70 XC70 ....Awesome video....took 15 mins to install blower motor andresistor on my .... Most time was spent trying to remove theelectrical wires from around the blower properly (there ... I was suprised how much bigger the fan is irl than it looked in this vid!
The relay in your blower motor is stuck on, there is a TSB for this issue. Replace the blower motor resistor and you'll be back in business. How does the resistor get power if the fuse is pulled? Replacing the resistor will cure both problems. TSB is a technical service bullitin seen below Subject:HVAC Blower Motor May Run Continuously After Vehicle is Turned Off (Replace Blower Resistor Relay)Models:2004 Chevrolet Avalanche, Silverado, Suburban, Tahoe, TrailBlazer, TrailBlazer EXT2004 GMC Envoy, Envoy XL, Sierra, Yukon, Yukon XLwith Manual Control HVAC (RPO CJ3)Built Prior to August, 2003
It sounds like you've got a bad blower motor resistor. The resistor is located under the right side of
the dash at the blower motor. A new resistor is not very expensive and it's a fairly easy DIY.
Hope this is helpful
Good Evening, If I am translating this properly your fan only works on the high setting? And the other settings do not change the speed? If this is correct respond back and I will help as much as possible.
Problem with blower motor is the blower motor resistor. They are usually located next to the blower motor, a couple of screws and a couple of plugs and your done. Autozone sells them for around $30 each. Wipers you may want to check for relays under the hood in the fuse block. There may be 2 relays 1 for low and 1 for high. I have switched relays from other working accesories and got wipers to work. Sometimes bad connection.
Your looking for the blower resistor. Its on the passenger side under
the dash. Two of the wires go the the blower motor. The wire connector
and the resistor can burn or corrode. The replacement is easy two
screws hold the resistor in and the connector can be replace with ****