My 2003 4x4 Sport was in for service on the front end. 2 days after getting it back I turned on the heater to clear the windshield - and had no heat.
Up till this time, the heater and AC had worked perfectly.
A few days ago I had time to look into it. The heater core was receiving hot water from the engine as it should. I removed the front seats, lower instrument panels pieces and glove box so I could see the wiring, ducts and servo motors.
All looked in order, but I disconnected and reconnected all the wiring. I also ran the control through the various vent positions to see that the servos were working. All OK, EXCEPT the servo for the mixing door did not seem to respond to the call for heat. I also removed the cabin air filter (it was very dirty) and replaced it.
Finally, I removed the thermistor that senses cabin air temp (to the right of the steering wheel behind the small grill of slots), cleaned off the dust and disconnected/reconnected the wiring.
Here comes the magic! Once I put it all back together, my heat worked just fine. Again, not very satisfying in that nothing was obviously broken or disconnected - but the system is now working fine.
Just in case there is any tie-in, I posted a fix on the brake booster pump today, 9/27. I had been having problems with the pump running on start-up. I "fixed" that at the same time I was working on the heater. Once everything was completed and put back together, the booster pump problem and the heater problem were both cured.
Up till this time, the heater and AC had worked perfectly.
A few days ago I had time to look into it. The heater core was receiving hot water from the engine as it should. I removed the front seats, lower instrument panels pieces and glove box so I could see the wiring, ducts and servo motors.
All looked in order, but I disconnected and reconnected all the wiring. I also ran the control through the various vent positions to see that the servos were working. All OK, EXCEPT the servo for the mixing door did not seem to respond to the call for heat. I also removed the cabin air filter (it was very dirty) and replaced it.
Finally, I removed the thermistor that senses cabin air temp (to the right of the steering wheel behind the small grill of slots), cleaned off the dust and disconnected/reconnected the wiring.
Here comes the magic! Once I put it all back together, my heat worked just fine. Again, not very satisfying in that nothing was obviously broken or disconnected - but the system is now working fine.
Just in case there is any tie-in, I posted a fix on the brake booster pump today, 9/27. I had been having problems with the pump running on start-up. I "fixed" that at the same time I was working on the heater. Once everything was completed and put back together, the booster pump problem and the heater problem were both cured.
