Hi there, totally new to this forum and sincerely appreciate the community.
I recently acquired a 1998.5 Ram 2500. As noted in the title, the blower motor stays on after the engine is off and key is removed. HOWEVER... it does eventually turn off after quite a long period of time (time out?). So...

I checked and tested the ignition switch and it does not appear to be part of the problem. My methodology was this...

a) I started the truck and let it run for a couple minutes, then shut it off and removed the key.
b) I noted that the blower fan was indeed still on.
c) I proceeded to remove the ignition switch and unplugged both wiring pigtails... the blower motor stayed on!? Clearly not the ignition switch in this case?
d) I plugged the ignition switch back in and re-fastened it.
e) l turned the blower motor switch to off, let the truck sit for awhile, went back out to turn the fan on, and as expected it did not turn on. (timeout?)

So... is this a control module issue? A stuck relay?

Baffled here.

Thanks in advance for any sage input.

Cheers!

 

Download the service manual for your truck from here. Wiring diagrams are in section 8W. have a look at the blower motor circuit, see if anything obvious presents itself. The switch provides ground path, so, I believe your problem is on the supply side of the circuit..... trace the power feed backwards from the blower motor, see what could possibly leave it enabled. (might be just a sticky relay.)

 

Thank you for the reply. My next test is to time how long it takes for the blower motor circuit to actually power down. It seems like it is consistent (takes quite some time) and not random, however... checking all possibilities is in order.

 

No electronic control modules in this ancient A/C / heater system. There is a relay in the PDC under the hood that provides power to the blower motor and the ***** on the dash connect the motor to ground via the blower resistor. The relay gets activated by the ignition switch via fuse 2 inside. I'd start at the relay.