Tech Tip:
Performing Calibration and Cool-Down Tests
Application:
1996-2000 Caravan, Town & Country and Voyager
Symptom: A/C Panel and/or Rear Wiper Indicator Lights Flashing
Theory:
When it comes to the A/C system, these vehicles have a unique way of letting you know they need diagnosis or calibration. The LED indicators for the A/C and/or Rear Wiper controls will flash. This can happen if an A/C component is replaced or even if the battery was disconnected for more than a few minutes. The procedures to reset everything are really not a big deal, but they can be hard to find in some service literature.
The Test:
What to do depends on which LED’s are flashing and how. Match yours up with the following list to get the appropriate procedure.
- Before
you start this procedure, the ambient temperature should be 60°F
or above. If this isn’t possible, try to warm the Evaporator Case
by running the HVAC system in the Full-Hot mode for a few minutes.
- With
the A/C off, set the Parking Brake and let the engine idle at normal
operating temperature. Turn Mode Switch on HVAC to Panel. Open all A/C
vents and set Temperature Selector to Full Cold.
- Press
and hold Rear Washer and Rear Wiper buttons at the same time for 5 seconds
and release. All LED’s on the panel should light up. The Rear
Wiper and Intermittent LED’s will flash alternately while the
test is in progress.
- After
approximately 60 seconds, if only the Rear Wiper LED is flashing, the
calibration was successful. If the Rear Wiper and Intermittent LED’s
are flashing together, calibration was incomplete. Turn key off and
restart the test. Remember, it will also fail if the Evaporator or ambient
temperature is too low. If the Rear Wiper and Intermittent LED’s
are flashing alternately, it failed the test due to a fault and there
should now be a stored code. See the Service Manual for Code-Retrieval
procedures.
The Fix:
Run the appropriate test from the symptom chart above.
Calibration/Diagnostic
test:
- Before
you start this procedure, the ambient temperature should be 60°F
or above. If this isn’t possible, try to warm the Evaporator Case
by running the HVAC system in the Full-Hot mode for a few minutes.
- With
the A/C off, set the Parking Brake and let the engine idle at normal
operating temperature. Turn Mode Switch on HVAC to Panel. Open all A/C
vents and set Temperature Selector to Full Cold.
- Press
and hold Rear Washer and Rear Wiper buttons at the same time for 5 seconds
and release. All LED’s on the panel should light up. The Rear
Wiper and Intermittent LED’s will flash alternately while the
test is in progress.
- After
approximately 60 seconds, if only the Rear Wiper LED is flashing, the
calibration was successful. If the Rear Wiper and Intermittent LED’s
are flashing together, calibration was incomplete. Turn key off and
restart the test. Remember, it will also fail if the Evaporator or ambient
temperature is too low. If the Rear Wiper and Intermittent LED’s
are flashing alternately, it failed the test due to a fault and there
should now be a stored code. See the Service Manual for Code-Retrieval
procedures.
Cool-Down
test:
- Before
you start this procedure, the ambient temperature should be 60°F
or above. If this isn’t possible, try to warm the Evaporator Case
by running the HVAC system in the Full-Hot mode for a few minutes.
- With the
A/C off, set the Parking Brake and let the engine idle at normal operating
temperature. Turn Mode Switch on HVAC to Panel. Open all A/C vents and
set Temperature Selector to Full Cold.
- Press
and hold Rear Washer and A/C buttons at the same time for 5 seconds
and release. All LED’s on the panel should light up. The A/C and
Recirculation LED’s will flash alternately while the test is in
progress.
- After
approximately 60 seconds, if only the Rear Wiper LED is flashing, the
calibration was successful. If the Rear Wiper and Intermittent LED’s
are flashing together, the test was incomplete. Turn key off and restart
the test. Remember, it will also fail if the Evaporator or ambient temperature
is too low. If the Rear Wiper and Intermittent LED’s are flashing
alternately, it failed the test due to a fault and there should now
be a stored code. See the Service Manual for Code-Retrieval procedures.
