Working on a 2000 Durango with a 5.2l engine. The owner says that the a/c never has gotten cold since they got it. I noticed that with just the front a/c on that the air is warm, and yes the compressor is engaged, but when I turn on the rear a/c both the front and rear blow cold. Has anyone ever seen this before?

Thanks,
Will

 

this is how my D is same thing. The front is never hot hot but the only way for me to get ac in the front is if my ac in the back is on

 

Sounds like a blend door issues.

 

What is that?

 

The blend door is a doorway that moves air over either the heater core (hot) or A/C coils (cold). If the blend door is stuck between then you get warm air.

Now there is manual and electric actuators that move the doors. In the older series 1999-2000 it is manual moved by vacuum. In the 2001-2003 it is operated by electric actuators. Here is the actuator description:

BLEND DOOR ACTUATOR
DESCRIPTION
The blend door actuators are reversible, 12-volt
Direct Current (DC), servo motors. The dual zone
front heater and air conditioner system has dual
blend air doors, which are controlled by two blend
door actuators.. In the dual zone system the passenger
blend door actuator is mechanically connected to
the passenger side blend air door. A second separate
blend door actuator is also located on the driver side
end of the heater-A/C housing unit close to the
instrument panel, and is mechanically connected to
only the driver side blend air door.
The blend door actuators are interchangeable with
each other, as well as with the actuators for the
mode door and the recirculation air door. Each actuator
is contained within an identical black molded
plastic housing with an integral wire connector
receptacle. Two integral mounting tabs allow the
actuator to be secured with two screws to the heater-
A/C unit housing. Each actuator also has an identical
output shaft with splines that connects it to the linkage
that drives the proper blend air door. The blend
door actuators do not require mechanical indexing to
the blend door linkage, as they are electronically calibrated
by the heater-A/C control module. The blend
door actuators cannot be adjusted or repaired and, if
damaged or faulty, they must be replaced.
OPERATION
Each blend door actuator is connected to the heater-
A/C control module through the vehicle electrical
system by a dedicated two-wire take out and connector
of the HVAC wire harness. The blend door actuator
can move the blend air door in two directions.
When the heater-A/C control module pulls the voltage
on one side of the motor connection high and the
other connection low, the blend air door will move in
one direction. When the module reverses the polarity
Fig. 17 Ambient Temperature Sensor Remove/Install
1 - YOKE
2 - CONNECTOR
3 - SCREW
4 - SENSOR
24 - 20 CONTROLS - FRONT DN
AMBIENT TEMP SENSOR (Continued)
of the voltage to the motor, the blend air door moves
in the opposite direction. When the module makes
the voltage to both connections high or both connections
low, the blend air door stops and will not move.
These same motor connections also provide a feedback
signal to the heater-A/C control module. This
feedback signal allows the module to monitor the
operation and relative positions of the blend door
actuator and the blend air door. The heater-A/C control
module learns the blend air door stop positions
during the calibration procedure and will store a
Diagnostic Trouble Code (DTC) for any problems it
detects in the blend door actuator circuits. The blend
door actuator can be diagnosed using a DRBIIIt scan
tool. Refer to the appropriate diagnostic information.
REMOVAL
The dual zone heating and air conditioning system
is equipped with two blend door actuators.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE
THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM
CAPACITOR TO DISCHARGE BEFORE PERFORMING
FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Roll the Instrument Panel Assembly back(Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - REMOVAL).
(3) Remove the HVAC unit from the vehicle(Refer
to 24 - HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - REMOVAL).
(4) Remove the blend actuators(Refer to 24 -
HEATING & AIR CONDITIONING/CONTROLS/
BLEND DOOR ACTUATOR - REMOVAL).
(5) Remove the drive shaft from the blend door.
(6) Remove the upper half of the HVAC housing.
(7) Slide the blend air module out of the HVAC
housing.
INSTALLATION
(1) Install the drive shaft to the blend air door.
(2) Install the blend actuators to the distribution
housing. Tighten the mounting screws to 2 N·m (17
in. lbs.).
(3) Connect the HVAC wire harness connector for
the blend door actuator to the actuator connector
receptacle.
(4) Roll the Instrument Panel Assembly back into
position(Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL ASSEMBLY - INSTALLATION).
(5) Connect the battery negative cable.

 

I would think that if it was a blend door issue the front air wouldn't get cold even when the rear A/C on.

Will

 

Could be a bad expansion valve. Have you had it serviced?