[92breadbox]

I have a 92 caravan....3.0 The fan switch will only work on high, and the only position that the heat will blow from in the windshield, no matter what button i press for it to blow from...I thought that maybe it was the control's themselves so i got new ones from the junk yard, i replaced them and its still the same problem, only this time i added a new one to the list, after hooking up the unit, the cable that controls the temperature, popped off, and it appears that i cannot push the switch in the cold direction without the cable resisting and snapping off. I do not seem to understand what has happened with this since this cable is just supposed to rest around this little hook. I would realli like to avoid a mechanic on this one...ANY SUGGESTIONS WILL BE GREATLY APPRECIATED! :huh:

 

[Wally_03]

I have about the same problem from my '94 3.3L. Air from front is luke warm, and it likes to switch from vent to defrost on its own!?? Heat from rear is hot. Have checked water valve, found to be operating correctly.
I would suspect your fan problem is due to a burnt out resistor, and i havent looked, but should be mounted in the ductwork in close proximity to the blower motor.
Temp problem is probobly a bad cable or door (or something stuck in it) Mine is probably the same thing, i will get around to digging into sometime soon (AS IT IS GETTING COLD HERE!)
I am stumped on the mode selector though, so hopefully someone has some insight

 

[gas28man]

breadbox and Wally,

When your fan switch only works on high, the blower resistor has gone bad. It's a dealer-only part, running anywhere from $16 to $26 depending on where you live. On the 96-00 models, it's on the passenger side firewall, accessible only from under the hood, and a major beyotch to get at. On the 01-07s, it's much easier. Literally a five minute job, right behind the glove box. On the older models I'm not sure where they put it, so I can't help you there. But that is the problem.

Wally,
As for the mode switch issues, again, I'm mainly familiar with the newer models, but on them, the issue is usually the control panel on the dash, so I'd start there.

As far as temp control problems, these can be an issue with the control panel as well, but a door or motor is equally likely to be the culprit.

The fact that you have both mode and temp control problems would seem to point to the panel, though. Mine went bad when a can of Dr. Pepper exploded all over it, so if you've had any spills in the dash area around the time the problem started, then you know what to do.

Breadbox
Your cable problem is a mystery to me. You obviously know how its supposed to work, and that's not happening. Try spraying down the cable with some silicone or lithium grease, and it you can find the vent/door it controls at the other end, lubricate there too. That's all I can suggest.

Hope my suggestions help. Keep us posted on your progress.

Rick

 

[Wally_03]

Hey guys-

I dug in to this today before work. Breadbox, where that temp control cable hooks on to the peg on the controller there should be an upper peg that helps to hold the cable down. Being a used controller, i wouldn't be surprised if it was missing...??? (ie broken off or something) compare it to your original one. when looking at mine, it seems to be quite secure with that peg riding on the cable. And yes, wouldnt be a bad idea to spray some silicone down inside the plastic housing on the cable.

I dug into the dash on mine a little and took the temp control cable off the controller. I verified that the door moved easily both ways, and heard it hit each side of the ductwork. I felt the coolant lines coming in and out of the heater core through the firewall. line in was hot, line out was like warm. i removed both lines and backflushed the heater core with a garden hose. WOW! all kinds of junk come outta that thing! reass. and perfect heat front and back now! No more cold fingers!

The issue with the mode switching to defrost is still unknown to me, and i did originally suspect the contoller, gasman. the thing that boggles me is this: Under nomal driving, mode selector works just fine, however, when i accelerate, no matter what mode i have it in, it will go to defrost, then back once i let off the gas. The only thing controlling the mode doors is vaccum, so somehow the changing vaccum is changing my doors. Main vacum line to the controller is plumbed off the brake booster.

I cant solve my own problem quite yet, but breadbox if nothing changed when you changed the controller i might suspect something is possible wrong with your vacuum line. like i said, on my 3.3 it is plumbed off the booster, 3.0 may be different. the main line goes through the firewall right with the lines for the evap from the expansion valve. The vaccum line for the water valve also comes out through there. i would check for a possible hole in that supply line, or pinched off. i really don't know, (and i should, but i usually work on eighteen wheelers) does vaccum increase or decrease with acceleration? if i find that out, i may be able to solve the problem.... good luck, and yes, keep us posted. i plan on doing the same

 

[Wally_03]

Did some looking. Vaccum will decrease with engine rpm. So a loss of vaccum is making the mode door move to defrost. Breadbox, i would really be looking at a complete loss of vaccum to your controller. with the engine running, disconnect some of the vaccum acuators. there is one behind the glove box on the right side for the recirc, and some more down by the gas pedal. they are all silver in color. if there is vaccum there you will be able to hear it when you disconnect the lines. Oh, and sorry, i forgot to look around for the blower resistor to give you an exact location. ill try to remember and get back to you. Let me know what you find