AC fan is not working, need the location of the motor resistor

[Prismatic]

Before I go and replace the motor (as per this thread http://www.taurusclub.com/forum/1703494-post2.html ) I'd like to test the resistor out.

I have no fan activity in any setting. The AC comp turns on, and the AC fan up front works as it should.

1999 SE 3.0 OHV

Thanks!

[Jeff K]

I assume you have manual HVAC controls (not EATC) If so: If the resistor fails, the blower will still work on high speed, as high speed bypasses the resistor entirely. So, if the blower doesnt work on high, the problem it not the resistor.

Test the blower motor. You should be able to access the 2 terminal blower motor connector under the dash or behind the glove box. Run 2 long, heavy gauge wires from the battery into the passenger compartment and try to power up the motor at its connector. If it doesnt run, replace blower motor. If it does run, trace the circuit back to the blower switch, fuse box, etc looking for an open.

If you have EATC, blower speed is controlled by a solid state controller.

[Prismatic]

Originally Posted by Jeff K

I assume you have manual HVAC controls (not EATC) If so: If the resistor fails, the blower will still work on high speed, as high speed bypasses the resistor entirely. So, if the blower doesnt work on high, the problem it not the resistor.

Test the blower motor. You should be able to access the 2 terminal blower motor connector under the dash or behind the glove box. Run 2 long, heavy gauge wires from the battery into the passenger compartment and try to power up the motor at its connector. If it doesnt run, replace blower motor. If it does run, trace the circuit back to the blower switch, fuse box, etc looking for an open.

If you have EATC, blower speed is controlled by a solid state controller.

It is manual HVAC, yes. The blower just shut off as I was driving. I managed to make it pop back on, albeit with the blower making an odd whine, by switching between off and vent a few times, but then it cut out completely.

I'll test the motor first, thanks for the tip on the resistor.

[SoNic67]

Spray some electric contact cleaner in the fan connector (the one under dash). Mine had some corrosion on that contacts and it would not start when cold.

[behlinla]

Could be the brushes going bad. Do you get any kind of ozone (electrical) smell when it's acting up? Bypass testing the motor is a good idea like Jeff said. If you have a test light, you can also check for voltage at the fan connector.

[Prismatic]

Hey guys. So after some testing I discovered there was no power making its way to the motor, but the motor was just fine. I ruled out the switch in the dash and finally decided to check under the hood.

The 40a fuse is fine, so I pulled the relay out to test it annnnnnd yeah, there was no testing required.



Ugh. It looked bad. I pulled the back cover off that fuse block and the harness is fine. I cleaned the contacts to bare metal again and put a new relay in. Works great. I'm a bit upset that the fuse didn't pop before that relay burned up. That pin literally jumps directly to the fuse.

Maybe corrosion? Who knows.

[Jeff K]

Glad to hear you found the problem! Corrosion = high resistance in circuit = little to no current flow = fan doesnt run. Fuses blow with excessive current draw, they dont blow with little to no current flow.