Hello everyone, new guy with an old problem. The heater fan was working intermittently on my 2008 Ram. I was letting it go until the sub zero temps moved out. I would have to hit the heater box to get the fan moving again. Today (50 degrees temp fortunately) the fan finally stopped so I removed it and the resistor. I tested the fan and it ran on another 12 volt source. The resistor was corroded, burnt and missing chunks of the ceramic so I replaced it with a new part. I tested the fan and it worked on all speeds so I reinstalled it. I took the truck on a half hour drive to give it a workout. The fan worked fine, I even turned the speed up and down just to test it. But, I turned the fan off and it wouldn't come back on. I read the threads on the ignition switches and installing a relay. I pulled my steering column apart. My ignition switch doesn't look like the ones in the YouTube videos and pictures in the repair threads. Its smaller with less wires. When I took it off and unplugged it, the blades aren't burnt and the plug end wasn't melted. I checked the fuses and they are good. I even gave the heater box a slap to see if it would work but still no fan.

Is there a relay or something else I'm missing?

Thanks

 

Update: went out to move the truck slapped the heater box with the fan on high. fan comes on at high speed...

ARRRRGGGGHHHH.

 

Are you getting power to the fan when it it doesn't work? Given your symptoms, I would really suspect a bad fan motor.

 

I'm thinking the same exact thing, especially after the resistor is already replaced.

 

Thanks guys I will check the next time it quits.

 

1A Auto has an excellent video on YT for troubleshooting your problem.
Many times the resistor burns because the fan motor is failing and drawing high current.

 

Fan was acting up again and required a kick or slap to start running again. This time I left the fan on high and restarted the truck, no fan. No voltage at all on the resistor, I pulled the plug and checked with my multi meter and a 12V light up probe. (I had replaced the old one in the first post so this is a "New" part. I know, doesn't mean it'd not bad.) Voltage at the inop fan was 12.37 volts. I tested the fans ground on the plug to another source with the light probe, it's good. So I plugged the fan back in and smacked it, it ran at 3/4 speed not full. Shut down truck, pulled resistor and started truck, It ran at full speed for a while and then started to slow down.
Anyone have any ideas what to do?
I will check 1A Auto's video jrsick.

 

Have you replaced the fan itself?

 

Not yet, I was watching You tube videos on the wiring. There is a connector to the left of the steering column that can develop a bad connection. If you shake the harness it will make contact an get power to the fan and controls.
Right now it's raining so I'll check tomorrow.

 

I think I read in there that the resistor or plug was partially melted at some point?

Sometimes when that happens, when the electrical contacts get hot, they can lose their temper (springy -ness) so from then on out, they are loose and then they create more heat and so on so on. When it runs, try to feel that connection for warmth. Also see if you can bend or crimp the electrical pins or clamps (either, or, or both) to make the connection tight.

Depending on what quality of resistor part you bought it may very well have failed again. Especially if it is trying to work through a high resistance connection (loose contacts)

I hope this helps you.

Please return and tell how any of this information worked for you, what you find, and how you eventually fix your vehicle (even if it is that you brought it to a mechanic / dealership for repair)
It is your feedback and final repair report that will make these forums useful to others in the future.
Many times I search and find the same exact fault that I am having, someone suggests how to fix it, the patron follows the suggestion and then never returns to say YEA! or NAY...


The forum thread just goes dead because the person fixed their fault and has not a care to offer the answer anymore. Please don't be that guy.

Cheers!