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Auto Repair

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Questions and Answers

Caravan Heater Problem

Q. I have a 1992 Dodge Caravan. 3 liter 6 cylinder. I believe that the cable adjuster for the heater is having no effect. When I pull the control unit out and grab the cable it is very difficult to move in or out. I think that the control on the heater core is stuck.

Please tell me that I don't have to tear the whole dash apart to get at that switch. Also, the blower directional switch stays on window defrost no matter the button I push. What can be causing that?

Thanks

A. Okay, you may be in luck here. You won't have to do much in the way of disassembly to fix that door. There was a TSB, number 24-11-94 issued 7/1/94 on just this problem. I quote from the bulletin:

SUBJECT:
A/C Heater Blend Air Door Sticking

MODELS:
1989 - 1994 (AS) Town & Country/Caravan/Voyager
1984 - 1988 (S) Caravan/Voyager

SYMPTOM/CONDITION:
Poor heater performance, or poor A/C performance, and/or temperature control lever difficult or impossible to move.

DIAGNOSIS:
Check the temperature control lever for a binding condition. If the lever is difficult or impossible to move, perform the repair procedure.

PARTS REQUIRED:
AR - 4318039 - Mopar Rust Penetrant
AR - 4318066 - Mopar White Spray Lube

REPAIR PROCEDURE:
This bulletin involves accessing the lower pivot and contact surfaces of the blend air door shaft to apply rust penetrant to free up the shaft and then apply lubricant to prevent further corrosion.

Remove the center floor console on vehicles so equipped.
Remove the floor air distribution duct.
On the extension which houses the blend air door shaft inside the heater-A/C housing drill a 3/32 in. (2.2 mm) hole perpendicular to the side of the extension and 3/8 in. (10 mm) up from the bottom of the extension to gain access to the blend air door shaft.
Spray a sufficient amount of Mopar Rust Penetrant into the hole drilled in step 3 and work the temperature control lever until it moves freely.
When the door moves freely, inject Mopar White Spray Lube into the hole for two seconds time in order to prevent further binding/sticking in this area.
Wipe the housing exterior clean of any excess lubricant and tape over hole in extension with black duct tape.
Install floor air distribution duct.
Install center floor console if equipped.
If movement of the temperature control lever is still difficult, inspect the temperature control cable where it attaches to the control for kinks. If kinked replace the temperature control cable. Refer to the appropriate service manual for cable replacement procedure.

As far as the mode switch goes, the vacuum line that supplies vacuum to the switch is most likely broken or kinked. You can trace it from the firewall to the engine and make sure it is in good shape. If it is, you can trace it on the passenger side. If it is in good shape, then it's probably a bad controller.