I recently removed the dash and replaced a leaky evaporator core (and heater core) to get my AC working again. I also replaced the blower motor resistor (BMR) since it had partially melted the connector.

The old BMR wasn't 100% faulty (just found parts rattling inside) and I have not changed the blower itself.

Any idea why the blower would run with no key in the ignition, AC controls are also in the off position? When I start the engine, the blower has no speed control and sometimes pulses.

Any help would be greatly appreciated, a week project has turned into 5 weeks and going.

 

It appears both Blower Motor Resistors are toasted -- assuming this would point to a tired blower motor that still works but is pulling too high of a load.

I'm thinking of replacing the Blower Motor and the Blower Motor Resistor (again) but is a ($300) mistake if I end up toasting them.

Anyone have some guidance on how to test if there is a short or something in the wiring causing issues?

 

Was it a used resistor? If you have auto climate control its the resistor thats bad.

 

brand new in the box - mopar part from the dealer which strikes me as very odd - I'll see if they will replace the part and add a new blower motor along with it.

 

Hmmm weird. That is a common problem with the ZJ's. Mine did it too so i have first hand experience. Did the original one do it?

 

i had one intermittent issue with the original - but the AC has been down for about a year. When I replaced the evaporator core I found the harness partially melted for the BMR which was why I decided to replace it as part of the project. THe new part worked for 1 day, reinstalled the original and also worked for about a day. Could be that the blower is pulling too much load, I did remove and inspect while I had the cooling "box" out of the Jeep. I didn't see buildup and it spun feely by hand so I chose to reinstall it. Appreciate the help.

 

Ah, something must be shorting it. I guess you could start by checking for amp draw on the wiring to the motor.