1994 Dodge Caravan Main heater vents

Tiny
LIBERTYSPIKE138
  • MEMBER
  • 1994 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 185,000 MILES
My heater has the option to blow heat out of the following.
Main vents, Main vents & Floor, Floor, Defrost
The problem is this is what it blows.
Floor, Floor, Floor, Defrost
I can't get any heat out of the main vents.
I made sure the heater controls are fine. Obviously the blower motor and heater core are fine. I traced all the vacuum lines from the controls to the corresponding canisters and made sure they are moving properly. A while back the heater only worked on high so I replaced the resistor pack from a salvage yard. If I shut the heater completely off and then turn it on a low speed I will get heat out of the main vents for a few seconds and then hear it close. Please Help!
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Sunday, November 23rd, 2008 AT 5:37 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
Did you check the switch itsels? It sounds like a vacuum problem. Are you getting enough vacuum from the supply line?

Joe
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Sunday, November 23rd, 2008 AT 6:18 PM
Tiny
LIBERTYSPIKE138
  • MEMBER
I checked the supply line at the engine and the controls and there is air. I tried swapping the controls for a known good one from my other caravan that I just sold and no change. The vacuum lines move the 3 actuators with no change and if I take them off and move them manually there is still no change.
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Sunday, November 23rd, 2008 AT 6:31 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
If everything is working and you still can't get heat through the vent, the duct work has to be disconnected or damaged. If the direction door is sending air to the vent duct, I can't think of anything else other than if a mouse built a nest in the duct work not allowing the air to pass.

Joe
Let me know if you find any of the problems I suggested. And, I'm sorry it took so long to get back to you. I lost a parent and have been a little crazy.
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Tuesday, November 25th, 2008 AT 9:41 PM
Tiny
LIBERTYSPIKE138
  • MEMBER
Another thing I have noticed is if I have the blower down real low I can get air out of the main vents for a little bit. When I turn the blower up higher I hear it close the vents and then nothing. Is there a door that could have broke itself and now the blower moves it to a closed position? If I gradually go back down there is still nothing until I turn it all the way off and back on again. Thanks for taking the time to help Joe. I lost my dad a few years ago so we all go through it but I wish you the best of luck dealing with it.
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Tuesday, November 25th, 2008 AT 11:24 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
Yes, it sounds that way to me. In the center of the dash, you will find the directional doors. Look there for one no opening properly.

I'll take your advice on the parent thing. It still seems too hard to believe. If I don't speak to you again, have a great holiday season. And I do look forward to hearing if you resolved this problem.

Joe
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Wednesday, November 26th, 2008 AT 6:47 PM
Tiny
ROYN
  • MEMBER
I have the same vehicle with the same problem. Inside the large black plastic heater/AC housing under the dash is a 'Mode Door' that controls which vent air exits (defrost, dash panel, dash & floor, or floor). The Mode Door is controlled by a vacuum Actuator near the gas pedal which has two vacuum hoses (brown & red). When a mode button is pressed on the dash, vacuum operates a rod on the actuator which moves the Mode Door. The rod is hooked into a hole on a small flange or tab of plastic under, and molded into, the Mode Door. It is not likely that the rod became unhooked because the rod can only be put into that hole when the actuator is hanging loose. The actuator is held in place with two hex head screws. What likely happened is that the plastic tab broke off. So when the blower fan is on the force of that air moves the Mode Door and the actuator rod is not controlling air direction.

Unfortunately to get access to the heater/AC housing is not possible without removing the windshield because of how four screws that hold the defroster ductwork to the dash were put in place. So to fix the problem you need to remove the lower dash panels, both on the left and right side, and the steel brackets that hold the ashtray/cupholder/storage box.

I drilled three 2" holes on the side of the heater housing to see the problem. Only one hole that large was needed, but at the time I didn't know exactly where the problem was located. I drilled a small hole in the remnant of the tab with the hope of wrapping a piece of wire abound the rod and through the hole to cause the actuator rod to operate the door, but that didn't work. The wire kept slipping of the rod as it moved.

I then made a small metal bracket with a hole, then attached it with super glue and a sheet metal screw to the underside of the Mode Door. With the actuator loose, I slipped the rod through my bracket hole, and reattached the actuator with the two hex head screws near the gas pedal. I tested it for a day or two and it worked. I then resealed the heater housing with the 2" discs of plastic and duct tape.
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Tuesday, November 10th, 2015 AT 6:16 AM

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