It is a chilly 34 degree day in Southern AZ and I want heat. I usually leave it at 75, but noticed the fan never kicked on. If I turn it to full cold, the fan kicks on and blows cold, but if I turn it to full heat, no fan. I can hit the front defroster and the fan kicks on full blast, but blows cold. The vacuum line to the heater control valve is intact and opening or closing the valve. I tried the defroster both with and without the vacuum line hooked up and it was still blowing cold.

The car is up to operating temperature. The coolant level is good.

I did a code check and it shows 21, but did not beep, so that means its an old code and I don't think the solar sensor would cause my issue anyway.

I tried searching - no luck. Suggestions?

 

Car fixed itself... for now.

 

I wonder if the blend door is activating. Even though that does not account for the fan not running when set to full heat...

 

Sounds like an HCV problem to me...

 

No, the fan wasn't activating when set to heat. Water was flowing through the heater core and I could see the valve actuator operating.

 

When I set it to defrost, it was very cold, so the blend door definitely wasn't routing airflow through the heater core. I don't know if there is a temp sensor separate from the gauge sending unit that maybe wasn't telling the HVAC that the car was warm enough to allow the heat to turn on. Normally it takes a couple minutes of driving before the fan will kick on so its not just blowing cold air.

 

Bump from the dead. I am now having a similar problem. The heat intermittantly works. Most of the time it works perfectly, but tonight (about the 3rd time its happened) the fan just wouldn't come on, no matter what I did. I would hit the A/C button (didnt leave it on for more than a second), and nothing different would happen. The climate control is working perfectly, but the fan just doesn't blow for some reason.

It has done this before, and it will come back on (I hope), but like I said it has done this before and its always works the next day.

 

Did you check for Climate Control Codes?

 

I checked for climate control codes. Came back 00, or no code. My problem is a little different, first, my car was making a noise, sounded like a leaf was stuck in the fan. The heat and all worked great, but sometimes the fan wouldn't kick on, then it would work the next day. When the fan doesn't work, it doesn't work on any temperature or defrost. The display works perfectly though. I looked today and the cabin filter was not there, so it's a possibility something got in there, but I'm leaning towards replacing the fan unless someone else comes up with something that could be the problem. Let me know!