Hi guys! For some reason, the heat stopped blowin in my 97 4 door blazer a couple days ago. Then, when leaving the parking lot I was in, I hit a bump, something clunked twice, and the heat started again. Today, it wasnt working again. I live in michigan, we're supposed to get hit with an "arctic blast" soon, and I need it working asap. Do any of you have a clue what this could be? And its not just heat, nothing blows at all. Ive switched everything on and off multiple times but still nothing. Also, when it worked, it only blew out of defrost and one vent above the radio, and everywhere else it kind of seeps out. Any help with this stuff would be greatly appreciated. Thank you

 

try turning it on and hitting the blower motor under the hood (pass side against the firewall) with a small hammer. prob time for a new blower motor.

 

Okay, I will try that. I was also just looking into the problem with my 4 wheel drive not working. I read a thread that said that a leak in the vacuum hoses or something like that could affect not just 4x4 but also the HVAC system, which is heater/ac. Could that possibly be it also? Not just a new blower motor? I didn't know that the heater and 4x4 were connected in any way until just now

 

The vacuum lines that come from the switch on the transfer case control the front axle and the doors in the HVAC vents. Meaning if you switch from windshield to floor the doors may not move. The switch on the transfer case is prone to fail. There is a ball valve in the switch that is supposed to prevent the transfer case fluid from getting sucked up into the vacuum lines. That ball gets stuck and the fluid can get sucked into the front drive axle actuator which is located under the battery tray. The fluid also end up in the vacuum reservoir (on your truck it night be a baseball sized canister that is attached to the hood. Some have even experienced fluid showing up in their ashtray inside the driver compartment. I do not know for sure if this would affect the blower motor, but I haven't heard of that happening. There is a very good link that goes into how to clean the system and replace the switch here GMC Sonoma & Chevy S-10 Transfer Case Vacuum Switch

 

Im gonna bump this one, I have the same problem with my blower motor. Had a 3 hour (well 4 hour with the road conditions) drive home today and I noticed my blower motor wasnt blowing anything, on any settings (1 through 4). Im looking for a checklist of how to diagnose exactly what it is, like start here, then go here, then do this, etc. Ive scoured the web and feel like its the blower motor but I would rather not replace it in below 0 temps right now....but I NEED heat. My toes we're frozen until halfway through the trip. I know to check fuses and tap it with a hammer, if neither of those work ill hot wire it to the battery and see if it runs, beyond that what do I do next?

Truck is an '01 ZR2 blazer

 

if the blowers fine it could be the blower motor resistor

 

the blower in my 98 is acting up and will only work after i unplug and plug back in...wondering what change out first?

 

I don't think vacuum has anything to do with the blower motor working or not. The other day when it was in the negative double digits here, I had the fuse blow on both my 99 s10 and blazer. I guess it was maybe so cold that the motor was drawing too many amps trying to turn. There is a 30 amp fuse in the under hood fuse box. It is labeled HVAC. You should check this one and make sure it's not blown. There's another one labeled HVAC in the cab fuse box on the drivers side dash. I don't think the one inside would affect the motor, but you could check that one too. I've owned my blazer for 10 years and never had this problem. It's weird that it happened on both vehicles the same day. That's what makes me think it was the cold. The blazer only took replacing once, the s10 took 3 before it got going without blowing.

edit: I just realized that the original post is from a year ago. I also see that the person that bumped it has already checked fuses I guess. You can check for voltage at the connection that plugs into the motor. Check for voltage in all speeds and see if you have voltage at all, and different voltage in the different speeds. If you have voltage, the blower should work. If it doesn't, your blower is probably bad. You can unplug the connector from the resistor, check the terminals there and see if there's voltage in all speeds. If no voltage, the switch is probably bad. I hope you can get it narrowed down.

 

Funny this gets bumped up again. First time my blower stopped working it was a fuse blown. Put a new one in and it worked. Couple days ago had the same issue and same low temps. (Windchill in the negatives). Fuse was blown but this time it blew the new fuse right away. So i brought the truck in and put the heater on it for two hours. Put a new fuse in and it worked. I called my uncle who is a certified gm mechanic and he said theres a good chance my blower motor is going bad.

 

Yep....blower motor bearings are worn and/or bearing grease is dried-out requiring extra current when cold and thus blowing the fuse.

Might be able to oil the bearings to get by until warmer temps, but requires blower motor removal to get to inside bearing....might as well replace it...but if funds are short, then could try some oil as a short-term fix.