I have no power to heater fan in 02 expedition. I have taken the plug of at the fan and with a test light tried both wires for ground and for power. It has neither one . These tests were done with switch and fan in on position. Also checked plug going to resistors. They also have no power. Fuses are good. Any Help would be greatly appreciated.

 

Do you have power to the switch?

 

no power to the switch. I said before that there is no ground at the fan but this was erroneos due to a faulty tester.there is ground at the fan. Also have power at fuse and changed fuses around in case of fuse not visibly bad. The power seems to stop somewhere between fuse box and switch. Any ideas?
Thanks
Ken

 

Just some guesses as I do not have schematics for this vehicle You can check for power at the fuse block in the cabin and work your way back to the battery. It's going to be in that direction. but there is ussally fuses in 1 of the 2 power distribution boxes and 1 or 2 accessory relay(s) (1 might be in the fuse box under the hood the other on the firewall) all under the hood for the blower. There might be a fusiable link some where too, check for power at the fuse box. No need in checking the fan If there is no power coming into the switch, it won't magically reappear after the switch.

 

Hope this may help! I don't have the 2002 wiring diagrams and am looking at a 2001 book but I doubt that they changed much. there are two sources of power for the heater blower first a 10 amp in the fuse box inside the veh fuse #24 and then a 40 amo fuse under the hood on the drivers side distrabution box. the 40 amp is fus #105 from that fuse the power is directed to a heater blower relay that is located in a box under the dash, I have never looked for that relay (have had no reason to) but the wiring diagram shows it to be up and to the right of the colmn hope you just have a fuse problem and dont need to look for the relay.From the relay the power goes directly to the blower motor, the switch and resistor are on the ground side of the system. the blower relay is actavated by the switch and the 10 amp fuse. hope this helps you with youre problem

 

I will go do some more checking and get back to you.
Thanks
Ken

 

You solved my problem. I thought all relays were inside the fuse boxes. When you mentioned the relays above and to the right of steering collumn I recalled the two flashers in that area. Well one is a flasher for turn signals and fourways the other ,it turns out, is a fan relay!The top pulled off as I was removing it and burned circuits were clearly visable. I replaced it with new relay and viola! it works! I cant tellyou how much I appreciate your help and all who gave advise. This is truly a great site

Thanks very much
Ken