Fan only works on high

[SlicksInRain]

My A/C will only work when the fan is on high and not at any other speed. My truck had this problem over 10 years ago when it was my dads. He would drive over a bump and it would go back on, but not a bump in this city is kicking it back on. Do I need to replace the whole set up, can I repair the switch or is this a wiring issue? Also do you think I can find a good one at a junkyard or do they all tend to go out after 20 years? Thanks!

 

[shaun89]

mine did the samething....i cant figure it out

 

[readymix]

Are you talking about the blower motor?
Check the resistor

 

[shaun89]

Are you talking about the blower motor?
Check the resistor

yep! is that on the fire wall near the actual blower motor?

 

[readymix]

In the general area

 

[SlicksInRain]

How do we fix this?

 

[shaun89]

How do we fix this?

im guessing just replace the resistor

 

[rjfguitar]

There is a relay or resistor that is attached to the A/C evaporater housing above the passenger side fender. There is a big plug that is plugged into it and has a few wires coming out of the plug. Change that resistor and it will be as good as new.

 

[shaun89]

There is a relay or resistor that is attached to the A/C evaporater housing above the passenger side fender. There is a big plug that is plugged into it and has a few wires coming out of the plug. Change that resistor and it will be as good as new.

awesome,thanks a lot!

 

[dyeager535]

The guys nailed it, it's the resistor.

Just for general knowledge, the switch gets 12V from the fuse panel on a single wire (brown). From the switch to the resistor the wiring is separated for each "speed". "High" on the switch is straight 12V to the blower motor, so it doesn't go through a resistor, which is why it still works, but only on high.

 

[shaun89]

The guys nailed it, it's the resistor.

Just for general knowledge, the switch gets 12V from the fuse panel on a single wire (brown). From the switch to the resistor the wiring is separated for each "speed". "High" on the switch is straight 12V to the blower motor, so it doesn't go through a resistor, which is why it still works, but only on high.

o cool that helps a lot, thanks for the details!

 

[SlicksInRain]

So that's the thing by the plug? Sorry I haven't been to my truck yet and I am still a little sketchy on what to change.

I just don't know exactly what it looks like and I misplaced my shop book.

 

[mudboggink5]

Ive been having the same problem, I will check out the resistor today

 

[dyeager535]

On a non-AC truck, the wires all go straight to the resistor plug. On AC, I think there is a relay tied in, but I'm not certain of that.

It's an odd plug as I recall, 4 blades...3 in a row, one offset a bit. I think my plug is gray.

The resistor "pack" is screwed into the heater or AC case. When you pull it you'll see the individual resistors on the underside.

 

[SlicksInRain]

I fixed it for $8. Thanks guys!

 

[mudboggink5]

I swapped out the resistor, and still only working on high. an other ideas

 

[iwaxmyjimmy]

check the plug itself sometimes the ground burns up when the resistor goes out.

 

[mudboggink5]

I'll check that out, thanks