It could be the control head or you have no vacuum getting to the control head. The defrost vents are the default,when there is a heater problem.

 

I also have heating problems.
Beginning at least a year ago, sometime would get no heat regardless of the position of the temperature slider - or sometimes 100% heat, and I'd have to turn on and off the fan to maintain a comfortable temperature. Sometimes it would go back to normal operation where I could control the temperature.

The AC needed a recharge shortly after I bought the van used so I just pulled the fuse from the AC clutch because in defrost position the AC comes on whether the temp is on hot or cold, summer or winter. I guess it was designed that way to dehumidify the defroster air.

Sometimes just driving with nothing on (no heat or AC), I hear the servo motor running?? I expect this is indicative of problems.

Now all the heater fan speed controls do not work, other than full - no problem, I understand the resistors go.

Someone also indicated another problem I used to have last winter... I had to turn the fan on high to get the door / deflector to "Thump" closed, then I would have heat until I turned off the vehicle. Now however I can't get it to "thump" closed anymore so I have not heat directed into the cabin.
The controls to direct air to the face, feet and defroster vents work - just no heat.

I ran the diagnostic today (by holding the Wiper and the Wash buttons at the same time). First time I ran it I didn't turn on the fan which I later read I should do. The first results ended in the indicator lights cycling between the Wiper Light flashing 1 time, and the Intermittent Wiper light flashing 4 times. When done the system indicated an error by flashing both these lights when I turned on the car and this condition would not clear until I re-ran the test as below.
After further reading, I later re-ran the test as suggested with the FAN on FULL, the TEMP on COLD and the Selector on FACE. It Ran now with only the Wiper Light giving me a single flash and kept repeating this. This time when I pressed the wiper button, it successfully terminated the diagnostic test with no lights left on.
* Anyone know what the single blink means? *
I'm suspecting like F150 noted, I broken nipple connected to an actuator or something like that...
I do not suspect a heater core, a thermistat or insufficient coolant.
I suspect a mechanical or electrical issue in the dash.
Anyone have any suggestions?
Thanks in advance.

 

I have similar problems with my 07 GC. Everything works except the mode control. The heater and A/C work fine but all air comes out of the mid level vents. No defrost, no leg heat. Recirculation function changes the sound but not the placement of where the air comes out. All indicator lights look normal. Ideas????

 

Welcome to DF
You could have a broken mode door or blend doors.

 

Anyone ever figure this one out? I have a 99 that switches to panel and defrost just fine. but no floor. Ran the calibration test and when finished, the rear wiper was not lit. Blend door works fine temp is okay , just no floor and with winter coming on, this is a problem. Any thoughts?

Thanks

 

Had Intrepid when the coolant level got to low heat would not work. Add fluid to where it should be, all was well.

 

The mode door actuator moves 3 different doors. there are arms that come out to each door pivot. Make sure when the acutator is moving that all 3 arms are moving their doors. And in mid year of 1998, the heater controls were changed so they were diagnosed with a scan tool. You can still run calibration but it will not give you codes or any of the potentiometer tests. You would have to use a scan tool for that.

 

Hi again guys ok new problem at closer Look the damn RPM and Speedo Needles are on the Wrong side of the pegs How does one fix that? and Still same problem with the Passager Side Floor Vent not closeing pls PM me if you have any Ideas

 

Try to recalibrate the hvac for that issue and see if it gets better. There were blend door issues in '01 but if it worked before, might just need calibration. The cluster would also just need to be run through self test and it will be fine.

STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION

The heater-A/C control module must be recalibrated each time an actuator motor or the control module 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. Simultaneously depress and hold the Power and Recirculation buttons on the heater-A/C control for at least five seconds. The manual heater-A/C control power Light Emitting Diode (LED) and Recirculation LED, or the Automatic Temperature Control (ATC) heater-A/C 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 heater-A/C control, and less than twenty seconds for the ATC heater-A/C control. When the LEDs or graphics stop flashing, the calibration procedure is complete.
4. If the LEDs or graphics continue to flash beyond the normal three minute (manual) or twenty second (ATC) calibration time, it indicates that the heater-A/C control has detected a failure and a Diagnostic Trouble Code (DTC) has been set. Use a DRBIIIŽ scan tool to perform further diagnosis. Refer to the appropriate diagnostic information. 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).

CLUSTER
To activate the Self-Diagnostic program:

1. With the ignition switch in the OFF position, depress the TRIP ODOMETER RESET button.
2. Continue to hold the TRIP ODOMETER RESET button until Sof </B>and a number (software version number (i.e. Sof 3.2</B>) appears in the odometer window (about five seconds) then release the button. If a fault code is present, the cluster will display it in the odometer display. When all fault codes have been displayed, the cluster will display “end”</B> in the odometer display. Refer to the INSTRUMENT CLUSTER DTC'S table to determine what each trouble code means

 

What is the name of this scan tool? my dad is trying to figure out repairs on my van and its having problems with heating and cooling but we have done the recalibrations and they come back with nothing thermastat has been replaced twice and the coolant is full we dont have time to take it to a shop with the hours that i work they are all closed when im off work