I have a 2001 Cherokee that I am having problems with the blower motor for the heat-a/c. The original problem was the motor would quit blowing and I would have to get out and tap on the motor to start it blowing again.
When I had time I installed a new blower motor.
Now with the new motor when I run it on Max A/C and the fan switch on high, the relay behind the glove box continually trips and resets. If I don't have it set on Max A/C it will operate on all 4 normal fan speeds but still will occasionally trip the relay and then come back on.
From what I have read here it does not sound like the blower resistor, and I have put in a new relay but still have the same problem. I am leaning towards it being a defective blower motor drawing to many amps and tripping the relay.
Before I pull the pain in the ***** to get to blower motor again I would like to know what some of the more experienced Jeep owners think about my problem.
Thank you in advance,
Mark

 

What does the connector and pins look like? Sometimes they get hot enough to melt.

 

The connectors were fine when I changed out the motor

 

I would check the wiring all the way between motor and controls could be a slightly bare wire just getting enough contact to arc and trip the relay.

 

X2
My first thought was the relay which you have already replaced.
Second thought was the fan itself which you have already replaced.
Only other thing possibly worth replacing would be the resistor. But before you do that and possibly waste money on a part not needed I would check the wires as mentioned above. I know on mine when I pulled the AC/heater control panel the plug on the backside was melted. I would check that and see what it and the wires look like before swapping that fan back out. Good luck!!!

 

I have considered the wiring as a possible cause and have checked what is easily seen as well as the connectors on the resistor, relay and motor and all are fine. What makes me think motor instead of wiring is the original problem was not a constant tripping of the relay since the motor would not come on at any speed setting unless I tapped on the motor itself and jarred the brushes into making contact again, then after installing the motor I started having the relay trip issue. The other reason I tend to believe it is not wiring related is the fact that the relay trip is almost exclusively only on Max a/c and the blower on high. If it was a wiring problem I would think the relay would be tripping on any fan speed rather than just on Max. Does my line of thinking make sense to anyone besides me? Also from what I have read here about the resistor is that if it is bad you lose all the fan speeds except the Max a/c if I understand its purpose correctly.

 

For the price of a resistor I'd swap it out, vs warranting out a blower motor. Its really the only remaining x factor.

 

I replaced the resistor and still had the relay problem. I pulled the blower motor and put in a used one I had laying around since the part store was closed and the problem is gone. The only reason I did not put it in first was to avoid changing it twice if it was no good. So back to the part store for a refund and hopefully this used one will go for another 150K miles. Thanks for the help everyone

 

Wow. Bad motor from the parts store that sucks. Glad you found your issue and got it resolved!!!