This 2006 Chevrolet Trailblazer came in with the complaint that the blower did not work at any speed. This repair applies to 2002 -2009 Chevrolet Trailblazers and GMC Envoys,2002-2004 Oldsmobile Bravada, 2004-2007 Buick Rainier, 2002-2008 Isuzu Ascender. The parts are the same but positions may vary for 2004 and 2005 Chevrolet SSR. All with manual A/C controls.
This Trailblazer has dual zone, manual a/c controls as seen in the picture below.
Since this is a very common problem I went straight to the blower resistor assembly. It is located under the passenger side of the dash. To access it the lower hush panel has to be removed. Two 7 mm headed screws are used to attach the panel to the bottom of the dash.
Once it is down there are some wiring connectors that have to be taken loose along with the satellite radio module. Not all vehicles will have this module.
With all of that out of the way, I could now see the resistor and the burnt harness connector attached to it.
A little different view. The red wire is visibly damaged.
I unbolted the resistor assembly by removing the two 5.5 mm headed screws.
I had to use a screwdriver to pry the connector loose from the resistor assembly.
The damaged connector.
As usual the red and black wires were the main wires affected. The needed parts are available at www.The-Electric-Connection.com . Please click here to order.
Now, it was time to splice one wire at a time. I started with the red wire and made sure I applied the heat shrink tubing as this wire has power on it all of the time. I did not want to blow the fuse or remove it either.
Stagger the joints.
Reassemble and this one is done.
Testing is as follows. Disconnect the 7 wire harness connector and inspect. If there is any sign of heat damage replace both parts per above instructions. If there is no sign of heat damage then check the following. With the 7 wire harness disconnected check for power on the red wire. It should have 12 volts at all times and it gets it’s power from the 40 amp blower fuse in the under hood fuse box. Next with the key on check for 12 volt power to each of the following wires as you move the blower speed switch from low to high. Yellow / low, tan / med 1, lt blue / med 2, purple / med 3 and orange / high. Remember, this test is done with the key on and the seven wire harness disconnected. Other than the red wire having power at all times, only one wire at a time will have power on it, during a proper test. If there is no power to any of these wires during the test , check the fuse in the driver’s interior fuse box. If only some of these signals are missing, you will need to inspect the blower speed switch and related wiring. Also you should do a drag test on the terminals to check the spring tension. Please click here for more instructions.
- Terminal “A” Tan = Speed 2, power through blower switch from HVAC fuse
- Terminal “B” Yellow = Speed 1, power through blower switch from HVAC fuse
- Terminal “C” Purple = Speed 4, power through blower switch from HVAC fuse
- Terminal “D” Lt Blue = Speed 3, power through blower switch from HVAC fuse
- Terminal “E” Black = Blower system, ground at all times
- Terminal “F” Orange = Speed 5, power through blower switch from HVAC fuse
- Terminal “G” Red = Speed 5, Constant power from BLWR fuse under hood
If all of the tests above are okay and you want to go a step further, place a test light or voltmeter in the wires going to the blower motor. If the light comes on or you have a 12 volt reading, the resistor and wiring are okay and the blower motor is faulty. This can also sometimes be confirmed by bumping the blower motor with the switches on. If the motor starts after bumping the motor is faulty. One can also remove the blower motor and apply 12 volts (power and ground) directly to the motor. Be careful though the motor will tend to jump and roll all over the place. Hold it firmly and be sure you are clear of the impeller as it could hurt you pretty easily.
One other note. If you have an amperage gauge, test the blower amperage draw while it is mounted in the blower case. Turn on surge amperage could go up to about 28 amps. Amperage draw at high blower should be in the 18 to 24 amp range. The lower the better. Restricted cabin air filters (if present) and dirty evaporator cores will cause a blower motor to draw more current while reducing air flow volume. These two conditions combined will significantly reduce the life of any blower resistor.
I have a 2002 trailblazer and have replaced the resistor and checked to make sure iam getting power out of the plug that hooks to it and i get 12 volts out of it and 12 volts on my different speeds when i check them but cannot get any power out of the new resistor and fan does not work any help would be great.
Awesome! Thanks a bunch Sparky and checking out the link now for the Blower Speed Controller. NCLady
It is highly likely that the blower speed controller is the cause of your problem. I have included a link to a similar repair on a Yukon. The part and the procedure are the same. The newest part number no longer has an issue working with older blower motors. So you do not need to worry about that part of the post.
http://www.sparkys-answers.com/2011/07/2003-gmc-yukon-bower-erratic-not.html
Got an ’06 Trailblazer with auto and digital A/C. My blower started working intermittently last week. On the highest blower setting it will either blow cold at high speed, blow at med speed, low speed or not blow at all. Today was the first time the blower stayed on a minute after I turned the car off & removed the key. It’s also blown only when in drive & not on brake, but didn’t do that today. The face & foot settings work, the defroster works (but it does not blow high when on high, blows at about med on high). Heat works also. A local (non-dealer) tech told me to replace both the blower motor & resistor as he was unsure of what it is, though he looked at the resistor! I left with no repairs & found your site. What’s your take? Thanks! NCLady
I might be able to help more if I knew more about your vehicle. I understand it is an 05 Trailblazer. Does it have auto or manual a/c? I ask because you mentioned that sometimes it will not turn off and that is more common on the auto systems.