Progress, but still some weird stuff

[jcormier]

So, my 2002 Jeep is now running like a dream, but I'm having some intermittent AC issues. If I turn the key quickly, the AC blower motor will turn on almost 100% of the time. If I turn the key to accessory, wait for the fan to start, then start it, the blower fan usually remains off. I've replace the blower motor relay to no effect. I just don't think I understand sufficiently how the blower motor circuit works to further troubleshoot. The resistor block is new, the relay is new, and the HVAC control module is new. All of the controls work when the blower motor starts, but that seems to be the issue is that it doesn't always start...

Anyone experience something similar?

 

[NskLJ]

So, my 2002 Jeep is now running like a dream, but I'm having some intermittent AC issues. If I turn the key quickly, the AC blower motor will turn on almost 100% of the time. If I turn the key to accessory, wait for the fan to start, then start it, the blower fan usually remains off. I've replace the blower motor relay to no effect. I just don't think I understand sufficiently how the blower motor circuit works to further troubleshoot. The resistor block is new, the relay is new, and the HVAC control module is new. All of the controls work when the blower motor starts, but that seems to be the issue is that it doesn't always start...

Anyone experience something similar?

Sounds like you may have a poor connection at the ignition switch circuit that powers the blower circuit. Could be connector at the ignition switch or internal. The connectors at the a/c controls also have issues.
Your last sentence is a little confusing, what “doesn’t always start” the blower motor or the vehicle?

 

[jcormier]

Just the blower motor isn't starting. The rest of the vehicle seems fine.

 

[NskLJ]

Just the blower motor isn't starting. The rest of the vehicle seems fine.

If you can get the blower motor to act up repeatedly, then check fuse #8 for voltage when the motor does not come on. If the fuse has no power, check for voltage at the ignition switch. Black/ orange wire pin #8 if it does not have power, check the input wire at the ignition switch connector pink/black pin 9 at the ignition switch. If pin 9 has power but #8 does not it would be the ignition switch or the actuator that turns the switch. ( it may not be turning all the way) check the electrical plug for melting.