1988 no air blowing/ no power to the switch

[pruett365]

I have recently noticed that my heater/ac does not blow any air. I get heat while driving down the road due to air being forced through the system. I have checked the coolant level and fuses and can find no problems. The connections to the blower and resistor have no power to them so I checked the harness going into the switch and I found that there is no power getting to it. I have had my technician friend look at it and he determined the same thing. I can not find a wiring diagram to save my life. Does anyone have any ideas???

 

[Harris]

Start on the other end; pull off the fuse/relay box beside the battery and make sure nothing is loose there and that you have power. The (I think it's a 45 amp) fuse should be marked on the inside of the top of the box. As far as I can tell there is one Hot When Key On into the relay and then out, which makes a straight shot to the blower, and then there is a set of wires going to and coming from the switch.

Open the fuse box in the engine compartment and pull the AC/Heater blower relay. Turn the key on. Check each connector in the relay socket until you find voltage. It looks like there should be two hot when the key is on, one for the blower and one for the switch.

You should also be able to bypass the relay (if you have voltage to the relay in the first place) with a jumper wire. At least that way you could identify a bad relay if the blower came on when you jumped it.

 

[pruett365]

My pickup does not have a fuse/relay box. There are 4 relays near the battery and none of these are for the heater.
My dad's '85 Ranger has a fuse/relay box.

 

[Mark_88]

There's another thread on this same topic, but I'll reply with what I'd offered in that one...the little switch on the heater box where the wires connect...that switch can rust out on the inside as mine did (88 Ranger) and if you replace that with a good switch (I call it a switch but not sure what exactly it does) your blower will work...

I tried replacing the blower itself and that does not work...the blowers usually don't 'blow' but the relay switch or whatever it is connecting to fails...

F Series trucks use the same 'switch' and are usually in better shape than any you will find in a similar Ranger/Bronco...I went through about five before I checked the F150s and found they work the same...wires may be colored different and some may actually connect differently...I have one in my truck now and can get a pic of the wiring if that helps...