2003 GMC Sierra Hvac hardly blowing out any air

elinglelb7 · September 26, 2016

Having issues with my AC and HEAT, they will both blow out hot and or cold with nothing funky going on, but no matter at what speed its on it will hardly come out. I swapped out the blower motor and blower motor resistor and still nothing. I saw on some other forums that some wires / connectors had heat damage either at the resistor and the fuse box but all looked fine to me and I was getting the correct voltage. What should I check next? Thank you in advance

Formulabruce · September 27, 2016

Hi welcome to GM-Trucks.com ! , Here is my opinion

1.IF (and its possible due to your year ) your truck has a Cabin air filter ( between motor and blender) you may want to pull it and replace. Gm removed the cabin filter in production due to just the problem you describe. There are Videos on you tube on that as well.

2. IF that's not it... You seem like you are on the right track, did you hear the Blower motor pick up speed?

3. If answer to #1 is yes, then you may need to work on the "blender" (left of the blower) and that can hang up and or block air if in wrong spot. It has its own motor. There a couple videos on you tube showing how it works.

Good luck, and update how you made out please for everyone's benefit !

Colossus · September 27, 2016

Yup, ditto on the cabin air filter, get it out of there and you'll start grinning

elinglelb7 · September 28, 2016

Hey guys sorry it took me so long to reply but I did find out that my truck is not equipped with a air filter. After finding that out I grabbed my multi meter and checked both the fan and the resistor again and now I'm only getting milli volts. Any ideas on where to test next?

Formulabruce · September 29, 2016

I have had to replace the blower speed switch on the dash on a couple 200-2003 trucks , thats your next stop. Remove dash panel is easy and just clips in at edges, then you can get that panel with switch on it out easily. Good luck!

Ccross88 · October 20, 2016

I just replaced my resistor yesterday because the blower wouldn't turn off even after my truck was off. After I replaced it and wired up the new harness color for color the blower worked but nothing came out of the vents. I pulled the blower out and turned on the truck and the fan was spinning the wrong way. So I reversed the to wires that go to the blower from the resistor and now it's running the way it's supposed to. Reverse the orange and purple wires to the fan. Not the black and red to the resistor. I tried that first and the fan kicked in without the truck on when I hooked up the battery.