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.
You should start by checking the fuses. They may have blown due to the damaged connector or during the replacement of the harness connector. There is a fuse box under the hood and one under the rear driver’s side seat.
I also have an issue with the heat damaged connector, looks exactly like your pictures, I’ve replaced the blower-motor resistor and the blower and have gotten no results at all a/c still not working at all
Disconnect the seven wire harness connector at the resistor. Turn the ignition on and check for power at terminals “A,B,C & D” as the blower switch is adjusted. Compare to the chart in the article. If power is not present, you will need to inspect the blower switch and it’s harness connector. If power is present one of a couple of things have happened. The new resistor has failed (possibly from a blower motor drawing too much current)or there is not enough current available at the terminals due to a high resistance in the control circuits (requires load testing the circuits).
Hi Sparky, I have a 06 Trailblazer and my blower resistor burnt out and I replaced it off the instruction on here. when I turned on the car for the first time all 5 speeds was working then it shut off and the only speed that works is 5 can you help me trouble shoot this problem please..
Thank you so much for this blog! My mechanic has worked on my system for the last six months replacing every part associated with Fan Controls multiple times. I ordered the parts from your link above and installed yesterday. The difference between the original connector and the upgraded is obvious. Instructions were flawless and my fan is working again now. Thank you again!