i have an 04 aviator. it has the dual dig. ac/heat and rear a/c heat. Sitting still it only blows cold, once moving it EVENTUALLY gets hot. If you have the dual function engaged its even worse. The rear has yet to blow warm air. I know nothing about heat in a car. I've read it could be a vacuum problem or a clogged heater core. Any ideas? or anyways to check? Also there are no leaks or smells in the car.

 

Welcome to the forum!

Does the temperature gauge suggest the engine is getting up to temperature as expected? Once it starts blowing hot does it get cold as soon as you come to a stop, or does it remain hot?

I don't believe any of the HVAC controls are vacuum actuated with the Dual Automatic Temperature Controls (DATC). The DATC does have self diagnostics that can be run, but I'm don't have the factory service manual for the 2004 model year to call out the specific procedure. You can try the one for the 2002 model year, listed below.

-Rod

• To retrieve continuous DTCs press the OFF and PANEL buttons simultaneously and release, then press the AUTO button within two seconds. All vacuum fluorescent segments will be displayed if there are no continuous DTCs present. Continuous DTCs are indicated by the presence of the degrees Celsius symbol (ºC) on the DATC module display. Record all DTCs displayed.
  
• If any DTCs appear, carry out the diagnostic procedure. Refer to the Dual Automatic Temperature Control Module Diagnostic Trouble Code Index and follow the ACTION for each DTC given.
  
• If a condition exists but no DTCs appear, refer to the Symptom Chart Condition: The DATC System Is Inoperative, Intermittent or Incorrect Operation.
  
• To exit and retain all continuous DTCs, press any button except DEFROST. The DATC module will exit the retrieve continuous DTCs mode and retain all continuous DTCs.
  
• To exit and clear all continuous DTCs, press the DEFROST button. The DATC module will exit the retrieve continuous DTCs mode and all continuous DTCs will be cleared.
  
• Always exit the procedure before powering the system down (system turned OFF). Once the procedure is exited the ignition switch must remain ON for at least 30 seconds to allow the temperature blend door actuators to automatically recalibrate.
  
• Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent fault occurs.

 

The temp is normal. I flushed the system yesterday and the heat was hot while doing so, but turned cool when finished. It eventually blows warm while moving then immediately turns cool when not on the accelerator. The rear air never heats up...

 

Did you happen to back flush the heater core when flushing the system? I wonder if maybe the issue now that you've flushed the system is an air pocket in the system. Did you flush the system before or after posting the original post above? If the heat worked fine before the flush, I'd definitely suspect air in the system.

-Rod

 

not thinking and sitting in 15 degree weather i only flushed the coolant. i'm having the heater core flushed and cleaned today. I noticed my inlet hose is hot but the return hose is cold. I flushed it after the original post. Its still the same after flushing. the rear heat has yet to blow warm air.

 

heat into the core, but cool water out.. sounds like the heater might be working and transfering the heat ... there is a blend door in the duct that takes the hot air and cool outside air and mixes it to get the correct temp. IF that door is broken, or the rod to the electric motor is broken, the door can flop a round. It might be bouncing from open to close as you move down the road and get the cool "ram air" into it to dilute the hot air from the heater.

 

door #5 in the photo bottom of this page

https://www.ford-trucks.com/forums/9...-please-2.html

 

some data from the past

2002 explorer blend door--- feb 5, 2007 post----

#1 pulled trim piece around radio and heater/Ac control ( unplugged heater/ac control)
#2 pulled center console out ( dont forget to remove to screws from back corner of console, you will have to pop off the corner plastic pieces to see these screws)
#3 removed the bottom part of dash under steering wheel ( 2 screws)
#4 removed metal dash support ( piece that goes from floor to dash behind the consloe, two nuts from floor and two bolts from dash)
#5 pulled the floor vent duck work from driving side ( 2 screws )
#6 removed several screws form dash in middle so it would move a little ( you may not have to do this but I did just trying to make it easier to get to the actuator)
#7 pulled the actuator ( 3 screws) and unplugged)
the top screw on top back corner is rough to get to .

you will need a 1/4 inch ratchet with a 7 and 8 MM socket, I also used a three inch extension on some of the screws.
you will also have to have a 8mm wrench to remove the actuator.


I replaced my actuator, it was not turning at all,appeared that the gear inside was gone. ---see the photo in this file------
You do not have to get this from the dealer. Advanced Auto ordered one for me. I had it the next day.I paid 49.88. I also found that a Hanyes manual was helpful also ( 18.00)Make sure you get the manual for the correct year you have. I was told that the 2002 and 2003 where the same. The manual I bought was for both years.The wording was not helpful ( as far as locating the front actuator but looking at the pictures helped alot.

I worked on and off on this a couple of days ( took some things apart that was not needed, I was trying to use the steps someone had told me about for a late 90's model, they are notset up the same way.
Once I figured out what had to be done I figure I had a couple of hours in on this.
You could make it easier to get to the actuator if you pullled the complete heater box off but this requires more things to take off ( to do this you would have to unhook and pull the heater core out0

 

would there be a vacuum to close that door to keep the heat blowing while driving? It stays hot while driving and you can adjust full range while driving. only when sitting still you get cool air. rear air stays cold regardless.

 

thanks for the help guys, i feel like i'm going in circles with this thing.

 

Ok.........was the heater working correctly BEFORE you flushed the system? If it was, it sounds like you have air in the system to me

 

no, thats why i flushed it. my first post was prior to doing anything to the car.