Electrical

Tiny
CARTERSCOTT
  • MEMBER
  • 1996 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 143,000 MILES
1996 Caravan SE. Air Cond., Rear wiper and ventalation switch lights blink all the time. Why?
Sunday, February 13th, 2011 AT 2:05 AM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,741 POSTS
Battery was disconnected or run dead, or the HVAC computer was unplugged. It has lost its memory and needs to be recalibrated. Here's a copy of the procedure from the service manual:

ACTUATOR CALIBRATION TEST

Set blower motor on High.

Set Mode position to Panel.

Open all AC outlets.

Set temperature to cold.

Press Wash and Rear Wiper buttons at the same time for five seconds until all leds flash.

All leds will turn on for five seconds.

The calibration test is running when the Rear Wiper and Intermittent leds are flashing alternately.

Acceptable result is the Rear Wiper led is the only one flashing. Press Rear Wiper to exit. At this point, the calibration and cooldown procedures can be run separately.

COOLDOWN TEST

Set the blower motor on High.

Set mode to Panel.

Open all AC outlets.

Set the temperature to cold.

Press Wash and AC at the same time. (See note at the end).

Then there's a note in the manual that says the test will fail if the ac evaporator is already cold. HUH? "To correct, operate system with AC OFF and the blower motor on high for three minutes prior to starting the test". That's probably why I remember putting the temperature to hot before starting this test.

All leds will turn on for five seconds.

Cooldown test is running when AC and Recirc. Leds are flashing alternately. If they flash at the same time, the test has failed.

To abort the test, press the Rear Defogger, Recirc, and Rear Wiper buttons or cycle the ignition switch off and back on.

The manual doesn't say what to do next, but as I recall, if the test passes, only the AC led will be flashing. Press it to exit the procedure.

Note: For the Cooldown test, the manual say to "Press Wash and AC at the same time". Later, it says "Cooldown test is running when AC and Recirc leds are flashing alternately". To start the test, I think they meant press the AC and Recirc buttons, not the AC and Wash buttons. Try it both ways if you have to.

Caradiodoc
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Sunday, February 13th, 2011 AT 5:03 AM

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