Ford: Heater fan either off or high - no in between

[Blakers]

Hello Folks,

Once again I come to you asking for help with my company work truck. It's an 06 F-250. A few weeks back the heater fan control stopped working except on high. All the other positions are dead. I was told it was probably the heater fan resistor, located in the air box near the heater core. I took it out and looked at it - all the resistor coils look intact, but have some heat discoloration, which is probably normal. Is there a way to test these with a volt meter or ohm meter. Could it be the switch bad instead?



Thanks for your help,

Blake

 

[PBJ2500CTD]

First check should be the resistor pack - yes, you can check it with an ohmmeter.
Second is to check the switch - usually the switch fails on the high setting due to the high current and subsequent heat generated.
Then again this is a newer truck and the engineers seem to reroute things through wierd boxes and stuff.

 

[Blakers]

Thanks! I wonder where I could find what the resistance should be?

Blake

 

[kenny61]

If you have 2 trucks that are the same test or swap a good one

 

[PBJ2500CTD]

And you can check the voltage at the resistance pack connector while switching the switch through its positions to see if voltage appears at each respective connection.

 

[ttbird]

9 x's out of 10 it's the resistor pack. But check switch like PBJ2500CTD said just to be sure. Have replaced many on both Ford's and Chevy's. Not so common on Dodge's though, from my years of wrenching.

 

[Blakers]

Thanks guys. I'll check the voltage at the different resistors first. Switching with a different truck might work too as we have more in our company.

My Dodge went through the heater trouble, but it was the switching between defrost, heat, dash, etc. Repaired once under warrantee and again when I had to pay $$ for. So far so good since.

Thanks,
Blake

 

[Blakers]

Thanks to you guy's help, I tracked the problem down to the resistor and replaced it for under 15 bucks. I switched it with a coworker's truck and found mine bad. Take care.



Blake