Repair Topics / Heater Fan

• Why does the fan motor work on high speed only?
• How to check fuses
• How a thermostat works
• Why wont my car heater work?
• How a cooling system works
• How does a car heater work?

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Car Heater Fan Question and Answer - This category contains featured questions as examples. They relate to most vehicles.

Question: 2003 Dodge Caravan mileage: 66,000. My heater fan stopped working. I put 12V across the motor and it ran. I checked the 40-amp fuse and it looks OK. I looked at the wiring diagram in the Haynes manual I have and it shows a relay, but I can't find the relay; I'd replace it if I could find it. It's not in the "power distribution center" under the hood, and it's not in the "junction box" under the dash. Do you know where to find this relay?

Answer: It is located on the junction box behind the left side of the dash.

Question: 2002 Ford Thunderbird mileage: 51,100.  The fan stopped working on it today.  I looked in the fuse panel to see if there was a blown fuse, but I could not locate it.  We did not receive the owner's manual with the car.   I have looked in the engine compartment for the blower relay.  I could not tell which one was which on the control panel there either.  The heater or AC is not working since the fan is not blowing.  Any info that you can give me would be very well appreciated.  

Answer:  The blower motor has failed.  Test it by checking for 12-volts at the blower motor with the blower switch on.

Question: 2004 Mercedes E500  mileage: 43,000.   I am having problem with my heater.  I can tell that the air is hot but the fan is not blowing it out.  I checked the fuse and also changed it and it still doesn't work.  I am trying to find the fan itself and am having trouble finding it.  Can you help me with this?

Answer:   It is under the dash, in the heater ductwork.

Question: 2004 Toyota Avalon mileage: 40,000. Without warning, the air conditioner & fans quit working. This car has an outside air temp display & it suddenly does not show a temperature reading. I checked every fuse I could fine with a meter. All OK. The car starts & runs fine & all other electrical works, i.e., lights, rear defroster, windows, door locks, seats. It is equipped with an auto mode for the air with a temperature adjustment that will control the blower speeds. This is not working, or if you try to punch manual blower speeds, (each button will light up) but will not turn fan on, or if you push the a/c button, will not work or light up. No engine service light either?

Answer: Check wiring for damage or loose connections. Check BCM module operation it may be faulty.

Question: 2002 Ford Windstar mileage: 70,000.  The heater/air-conditioning fan does not appear to have enough volume blowing out the vents.  I put on new fan and washed out the air conditioning coil, but it didn't appear to help.  I also straight wired the fan directly from the battery to see if it was an electrical problem in the speed control.  The volume didn't change.

Answer:  The "doors" in the heater ducts may not be opening.  Check vacuum hoses for leaks or loose connections in the engine compartment.

Question: 2004 Audi Quatro mileage: 25,000  Lately the heater fan has been making odd sounds at regular and low fan speed.  High speed is ok.  Tonight, I turned the car off to run in to the coffee shop.  (Note: the heater fan was making that loud noise.)  When I started the car up, I had no headlights, signal lights, and the climate control.  (No heat) also no seat warmer.  The car ran ok.   Parking lights and instrument panel are fine.   I checked the fuses and alls well.  What could be the problem?

Answer:   We are guessing that the fan motor shorted out causing a fusible link to fail.

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Repair Topics / Heater Fan