Heater gone -5 degrees CODE RED!!

[gt1009]

So today it was -5 to -10 degrees. I get in the truck and hope to god that it starts. Started fine, but when I go to flip on the heater after warming up the engine nothing happens. So I drive around all of today with just the airflow that comes from having the heater turned on. Barely enough to keep the windshield clear. Please tell me there is a simple relay or fuse that has gone and where it is so I don't have to tear apart the dash and change the blower motor.
Thanks,
Greg

 

[Recovry4x4]

Even if it is a blower motor, it's easily access under the hood. 10 minute job IIRC

 

[citizensoldier]

So you just dont have a blower fan working? or the motor wont warm up? Whats the engine temp at? Is your antifreeze up to par? Could be freezing up on you and blocking the heater core or you could just have a heater core full of gunk.. Do you have something in front of the radiator to keep it up to temp? More details and I am sure we can help..

 

[CCATLETT1984]

Check the fuse first, if its good then check the voltage at the fan under the hood (fan switch must be on and ignition must to in the "run" position, engine can be off)

if you have voltage then you have a bad fan motor, its not a hard job to replace. TIP: place some old blankets or padding on the enigne, makes it more comfortable to lay over while working.

 

[maxim]

Fuse, motor shot, or loose connection.

 

[CCATLETT1984]

please note that the post states that he only has the airflow that comes from flipping the defrost selector, and that it barely clears the window. He's getting heat, just no fan to blow it.

 

[DDoyle]

Not having a CUCV - but having driven a number of GM autos - IIRC, back in the day that these were being made, the blowe speed was reduced by a resistor. This resistor is mounted in the duct work under the hood with a plug-in electrical connector. If this resistor failed, the result was no blower. Like the motor, its easy access, and a two minute job to replace.

Its been a good ten years since I put a wrench on a Chevy pickup, my memory may not be the most clear - but maybe I'll jog someone else's memory.

HTH,
David

 

[CCATLETT1984]

I'll have to look at mine.

 

[FMJ]

Blower should still work on the high setting, the plug on the blower housing goes to the resistor, even if you unplug it, the blower should still work on the highest setting.

 

[Monty]

When I bought mine the blower didn't work, I started the truck turned the blower on and took a reading with a multimeter at the blower motor. I had 12+ volts I drove to Napa and got a replacement. I think it was $28.00.
Take your old blower motor with you when you go if this is your problem, they have 2 diffrent ones and one works and one won't.

Chad

 

[majortom]

Common GM blower Fits all 1973-87 Trucks and full sized GM cars, Sometimes when it gets real cold the blower will not spin Open the hood and firmly wap the end of the blower motor with a medium sized weapon, worked for me at minus 17

 

[Somemedic]

Had a dude sell me a blower motor on ebay that listed it as a "arctic kit" blower motor... Maybe it wasbut it spun backwards from the original motor. Cest la vie, even if the resistor died the motor will spin on its highest setting like was stated. Thats how mines been since last summer. I believe the resistor is mounted on the firewall on a diamond shaped plate with a small 3 or 4 wire harness towards the pass side. as I recall you need a small hex head wrench for 2 bolts and theres some wires/hoses/crap within close proximity but it doesnt look like a long drawn out job

 

[CARNAC]

Ok, I have what I think is the same problem since I got my truck. I only get luke warm air at best after an hour of running.

I replaced the resistor last night (I am assuming the oval 4" by 2" thing with coiled wire on the inside and two small screws and a 4 prong electrical connection on the outside).

I can distinguish a different force of air at the duct but the medium and low settings are significantly lower than the hi setting.

Antifreeze and radiator were installed in July. I checked the fuses about a month ago and couldn't find a bad one.

 

[mangus580]

How is your thermostat? Whats your engine water temp?

If you have moving air, I would suspect your thermostat next. Make sure its a true 6.2 tstat, as the cheapie parts houses like to sell you the wrong one...

 

[majortom]

Check the air door that is controled by the temp slide on the dash. Leaves and trash stop them from closing and allow cold air to bypass heat core. We blow compressed air in all the heat ducks, tons of crud comes out. The heater works much better after cleaning.

 

[ARMYMAN30YearsPlus]

Some units installed valves in the heating tubes or on the block to cut off the heating core did you check to see if there was one that is shut? Other than that I would say a heater core blockage.

 

[CCATLETT1984]

Guys, he has heat, the FAN doesnt work. Please pay attention here

 

[JWNathan]

Necro post. I too am having a similar problem. My blower motor wasnt working, so I pulled it thinking it was bad, I bench tested it and it was fine. So I put it back in and used a jumper wire to verify it had a good ground, it spun just fine.
Now heres the part that is giving me fits. With the key on and fan switched to high, I am getting 12volts at the motor plug under the hood, but with a load (a test light) the voltage dropped to nothing. To test this I used a test light and meter in parallel, unhook the light and the voltage shot up to 12+.

Any ideas what may be happening? I am at a total loss here.
-Jesse

 

[CDN-CUCV]

I've gone through this with a couple Chev's including my M1009 just two weeks ago. The bearing in my blower motor was going and it had put a strain on the fan switch and the power wire going to it. It finally fried the wire going to the switch. Sometimes the the switch itself will overheat too and fry. Replaced that as well before.

In my case, I had to replace the blower fan but also a short length of wire leading to(or from, can't quite remember of hand) the fan switch on the heater control. The last wire was cooked. So, check fuse and the blower motor resistor, located to the right when looking at the motor under the hood may be suspect as well. It's red, has four wires and is attached to the blower housing. You may want to check your fan speed switch and it's wiring for any signs of heat damage. Cooked wiring can cause resistance and ultimately failure of the circuit. Good luck.

 

[ssgtwright-usmc]

Look at the resistor going to the fan on the firewall. Had same problem and it was shorted out because of it touching another wire.
You will see it since the plastic is melted going to that resistor.
Cut/splice/and wrap.