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Discussion Starter · #1 ·
I am having an issue with my wifes 2007 trailblazer, today after work i got in it turned on the a/c and nothing not at any level 1-5. I checked all of the fueses all are fine. also the a/c light blinks three times and then turns off.
I have searched this forum and cannot find any help thank you
 

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2007? No warranty left?

I have the 2004 shop manual, and don't recall ever seeing a warning indicator that involves flashing the light 3 times.

Does the compressor clutch click on for any length of time when you start up?

If you turn off the AC compressor with the button, does the blower fan still fail to operate on speeds 1-5?

Might be relay 44 if it's just the compressor clutch failing to engage, or you could have a leak and all the refrigerant is gone and the low pressure safety switch is making sure the compressor isn't damaged.

Can you confirm you checked underhood fuse 35, and rear fuse block 39 and 44?

Do you have an EXT and rear aux AC?

A scan tool can communicate to the HVAC controller and PCM to check pressures and temps in the system. You may need a professional with that tool.
 

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Discussion Starter · #3 ·
yea no warranty 37200 miles haha

I checked all of the fuses agian and they are all fine.

the a/c compressor engages just no air blows out of the vents in any setting.

maybe the blower or one of the components bad. is there anyway to check that?

thanks
 

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Sounds like the control module or the blower, for sure. The most common failure of these vehicle's HVAC systems is the blower motor resistor pack. Run a search here on trailvoy for the "how to change it" threads. Cheap and available in the aftermarket.

But they almost always fail one or more ranges of speed, not all at once.

Do you have a voltmeter and can check voltages for me?

Start with putting the fan in speed 5, and then checking the voltage on the RED and the PURPLE wires on the resistor module behind the glove box.

The blower motor itself may be jammed from junk falling into it.
 

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Discussion Starter · #5 ·
I could not find a purple wire i just had red and black. I used the pictures from this thread to guide me http://forums.trailvoy.com/showthread.php?t=54119 picture 5 is what we are talking about correct?
My wires are red and black, i checked the voltage and at 5 volts i had nothing but 1-4 i had 10.5-10.6

I am lost if there is voltage there why wont the fan come on? thanks agian
 

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When you're checking the voltage on the motor's red wire, is it plugged in? Can you confirm the motor's black wire is at ground (near zero volts).

If it's plugged into the fan, and voltage is there on red, and ground is there on black, then the fan's bad.

But if you're on speed 5, and the fan is plugged in, and the red motor wire has nothing, then the problem is not entirely in the motor but upstream in the resistor pack or wiring.

Got any friends you can shove the schematic into their hand and ask them if they recognize the symbols? If they say yes, then shove a beer in the other hand, and tell them to follow you to the vehicle. :D
 

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Discussion Starter · #7 ·
Ok well I have changed the resistor pack and bench tested my fan. i quess that leaves just the control panel right? thanks again for your help
 
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