heater motor not working.

DarkoStoj

Founding Member
Sep 4, 2002
928
11
39
Detroit
www.pacific-motors.com
what are the ways I can start troubleshooting how to get my heater motor working again? We bought this 65 mustang and it doesnt have a heater core in and the heater hoses just bypass it, but we want to reinstall it. The motor and box is all there but the heater core isnt. So where do I start checking to see where the problem is?
 
  • Sponsors(?)


StangNet created a new car social app called knowmoto! Add your Mustang or post a photo in the knowmoto app and enter for a chance at a $100 gift card from LMR. Click the LMR Logo for more about the knowmoto Mega Thread!

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
4,818
1
69
BC Canada
Visit site
I'd start by measuring the voltage at the blower motor. No voltage means a wiring or switch failure, +12V indicates a failure of the motor itself.
 

Tim65GT

Active Member
Feb 24, 2004
1,149
2
39
60
West Texas
Here is a simplified diagram of the blower circuit.

The motor gets 12v from the fuse box and the switch regulates the ground potential through a resistor assembly.

FanSwitch.jpg
 

Attachments

  • FanSwitch.jpg
    FanSwitch.jpg
    19.7 KB · Views: 1,703

DarkoStoj

Founding Member
Sep 4, 2002
928
11
39
Detroit
www.pacific-motors.com
Here is a simplified diagram of the blower circuit.

The motor gets 12v from the fuse box and the switch regulates the ground potential through a resistor assembly.

FanSwitch.jpg
NICE! I should be able to figure it out with that.

so there is a fuse that runs to the blower right? I guess that will be the first place i check.
 

Attachments

  • FanSwitch.jpg
    FanSwitch.jpg
    19.7 KB · Views: 7,454

suki243

Member
Dec 19, 2006
662
0
19
Southern California
the current from the fuse block runs to the motor. Its the source, its in the engine bay, there are two wires that go to the motor, check the current on the brown one. But when i wired mine, i remember that the wires had become black and hard with dirt and buildup so check both wires i guess.
If no current is being received there, then check the fuse box for a fuse. I'm not sure if the heater has its own fuse, i doubt it, its probably on the accessory fuse
If there is current. then make sure that there is a wire plugged into the heater box prongs, theres a set of three and one below. The one on the bottom is supposed to receive current from the back of the heater motor. So check if the wire is still in tact using an ohm meter.
Im not 100% sure how to test the switch itself. :shrug:
 

spirockp

5 Year Member
Mar 26, 2004
465
12
39
NJ
OK funny I just did this myself. I guess winter is here and we all would like some heat.

Step 1. Hook the 2 wires coming out of the fan and connect them to the battery. Doesn't matter which one goes where, we,re just seeing if it spins.

Step 2. If that works reconnect them. Turn the ignition on. Take the wire, should be yellow, off of the resister on the heater box and ground it. The fan should also spin.

Step 3. If all that worked, unconnect the wires coming from the heater switch and connected to the resister. Take the same yellow wire and connect it to one of the 3 wires coming from the switch. By doing this you are bypassing the resister. Try to turn on the fan by switching to low, medium, or high on the heater switch. One should turn on the fan.

Step 4. If all that worked, replace the resister. That's what I needed to do.

Good Luck.
 

DarkoStoj

Founding Member
Sep 4, 2002
928
11
39
Detroit
www.pacific-motors.com
OK funny I just did this myself. I guess winter is here and we all would like some heat.

Step 1. Hook the 2 wires coming out of the fan and connect them to the battery. Doesn't matter which one goes where, we,re just seeing if it spins.

Step 2. If that works reconnect them. Turn the ignition on. Take the wire, should be yellow, off of the resister on the heater box and ground it. The fan should also spin.

Step 3. If all that worked, unconnect the wires coming from the heater switch and connected to the resister. Take the same yellow wire and connect it to one of the 3 wires coming from the switch. By doing this you are bypassing the resister. Try to turn on the fan by switching to low, medium, or high on the heater switch. One should turn on the fan.

Step 4. If all that worked, replace the resister. That's what I needed to do.

Good Luck.
PERFECT! this is exactly what i was looking for. Thanks!