I have an 05 caravan, xmas morning the heat stopped working and it only blows cold air. We have since replace the resistor switch, the thermostat, and the dial panel. Both hoses coming out of the firewall are hot, I had a mechanic look at it and he says he can see the flappers on the drivers side moving, the rad has been burped. i would get heat if i used the circulated cabin air but then my windows keep foggin up. I now get some warm air threw the vents and when sitting it blows hot but when I'm moving (esp on defrost) there's no warm air at all. I'm at my wits end... can anyone help? I've already spent a fortune on diagnostics and what I was told was sure fix but to no avail....

 

are the hoses in and out of the heater core so hot you can't hold on to them?

 

Did you run a calibration procedure after replacing the panel?

 

I could touch them but wouldn't hold on to them for a long period of time.

 

No.... wasn't aware I had to and for that matter how to...

 

A/C-HEATER CONTROL CALIBRATION

The A/C-heater control module must be recalibrated each time an actuator motor or the A/C-heater control is replaced. If the vehicle is so equipped, the calibration procedure also includes rear HVAC positions for each actuator motor.

1. Turn the ignition switch to the On position.
2. If equipped with the manual temperature control (MTC) system, press and hold the Rear Wipe/Wash and Recirculation buttons for at least five seconds. If equipped with the automatic temperature control (ATC) systen, simultaneously press and hold the Power and Recirculation buttons on the A/C-heater control for at least five seconds. The MTC A/C-heater control Rear Wipe/Wash button light emitting diode (LED) and Recirculation button LED, or the ATC A/C-heater control Delay and Recirculation graphics will begin to flash when the calibration procedure has begun.
3. The calibration procedure should take less than two minutes to complete for the manual A/C-heater control, and less than twenty seconds for the ATC A/C-heater control. When the LEDs or graphics stop flashing, the calibration procedure is complete.
4. If the LEDs or graphics continue to flash beyond the two minute (manual) or twenty second (ATC) calibration time, it indicates that the A/C-heater control has detected a failure and a Diagnostic Trouble Code (DTC) has been set. Refer to Body Diagnostic Procedures to perform further diagnosis. The LEDs or graphics will continue to flash even after the ignition switch is cycled Off and On, until a successful calibration is completed or until the vehicle has been driven about 13 kilometers (8 miles).

 

thanks I'll try it tonight and let ya know if it work.

 

I did it and the re-circulating air button continues to blink after.... still no hot air

 

Might check your thermostat to make sure it's not stuck open. That's an old fashioned problem that's been around as long as cars. Might as well try the $2 fix first.

 

Remove the Blend door motor, see if it works. does the motor moves when you adjust the temp?
here is your blend door motor,


4 - DRIVER BLEND DOOR ACTUATOR (DUAL-ZONE)

5 - HEATER CORE

6 - BLEND DOOR ACTUATOR (SINGLE ZONE) OR PASSENGER BLEND DOOR ACTUATOR (DUAL-ZONE)



try stick your finger or small screw driver into the Blend door motor slot and operate the blend door manually, see if it change the temp. I've seen linkage on the side of the HVAC housing binds.

Have you tried flushing the heater core yet?
also, pressure test the coolant system, see if there is any big leak somewhere. Believe it or not, a Radiator cap not sealing could result poor coolant flow.


is your system Auto temp control, or Manual temp control? dual zone or single zone?