2nd Gen Non-Engine/Transmission 2001 A/C / Heater temp control problem

[s2Mumford]

My heater / air conditioner temp control knob on the dash has gone binary.



It's either "cold" or "hot", witn no in-between adjustability.



I'm either freezing cold or baking hot.



What's the deal and how can I fix it?

 

[ntillm01]

You might do a search on this too, but I have seen a few folks report that the blend door actuator motor ends up being the cause. Your 2001 HVAC rotary knob send a voltage signal to the blend motor, which in turn moves to a determined angle based on the voltage. When they flake out, they only move to one extreme or the other.



The service manual recommends putting the control in "mid" before you re-connect the batteries after replacing the blend motor. Keeps the initial power-up at full hot or cold from binding the motor at one of the extremes.

 

[RBallard]

I bet it not the AC controller. I have been through this! Underneath the passenger side glove box is the blend door actuator. It is held in place by a couple of screws and you'll need a one of those $3 "S" shaped compact craftsman screwdrivers to get one of the screws out. There is a plastic key that breaks between the blend door shaft and adapter. Once it breaks the blend door is either loose or out of alignment thus giving you all hot or cold.



I was able to repair mine without the key using epoxy but I also ordered a new adapter from the dealer for around $12. I'll see if I can dig up a part number tonight. I didn't get the plastic key so It must be included with another part.



While you have the blend door servo out, you can check it's operation by moving the selector. You should see it move with each click. BTW a new servo at the dealer is $115.



Darkhorse and I just had a thread about this in the last week or two.





Bob

 

[s2Mumford]

Awesome, thanks a lot!

I will tweak out on it.



Also, where is the best place to get a shop manual?



A thousand thank yous

 

[ntillm01]

RBallard: I remember the plastic key problem you had, but I thought it was the blend door motor that you ultimately had to replace.



s2: I got my service manuals by calling the number in the back of the owner manual. I think you can order on line too.

Not cheap, but lots of good information! The wiring diagrams alone are priceless.

www.techauthority.daimlerchrysler.com

Let us know what you find! Good luck!

 

[pwknapp]

Thanks for the info. Mine won't run anything but hot air no matter where I put the thermostat.

 

[RBallard]

My neighbor, at Chrysler mechanic, lead me to believe that the AC is an intelligent system. That the servo motor self adjusts which is why I never worried about alignment. He brought the DRBIII over and we went through everything. Turns out the system aint too smart! I bought a servo and heater controls prior to the DRBIII thinking it had to be one of those. I played with the servo for a bit taking it completely apart, manually moving the position of gears and putting it back together. No matter what position, once power was on it, it always returned to the position of the selector. I then noticed that the shaft wan't aligned with the key way so I put globs of epoxy in there and filed it flat to fit making sure the flat was in the correct location. Like magic it all worked again. In the mean time I took the extra plastic adapter to work and made a new one from brass. When or if the epoxy one breaks, I'll try the brass one.



As for the factory manuals, I picked up a 2002 off ebay for around $30 and it included the power train diagnostic manual. I lucked out when Dodge redid the 2002 1500 because they were deleted from the manual. I guess the 1500 people are what drives the costs up. Let me know if you need anything in particular such a diagrams, I may be able to PDF you some info.



Bob

 

[ntillm01]

I get it now, Bob. Yes, there are some systems in many of today's vehicles that need a scan tool to "learn" the servo positions. At least up to 2002, these aren't that smart.

 

[BRI7070]

Talk about bringing ud post.....

Any answers? I have the same problem and the local dealership HVAC guy told me that when I replaced my heater core that I did not connect a ground wire somewhere. The way he explaned it to me, if I remember correctly, is that the servo reads the impedance to ground to control the temp. with out the ground connected it will give full hot or full cold and not stop anywhere in between.

Now i have to gpo ground wire hunting. out comes the dash, again. O lucky me