log man

i guess i am the new guy, i have a question about my 2001 ram, i cannot figure this out, my heater + a/c control only works either wide open hot or cold no inbetween i even tried putting the control in the middle and disconnected the battery and no luck . either i freeze or i sweat, any help would be great.....log man.

badme

I am just guessing here, but I think when you switch this from cold to hot at either end of the spectrum it has a switch with a variable resistor in the middle. The resistor must be bad so it only works at the two ends, so the blend door only goes from hot to cold with no mix.

WestTN

The resistor block is the reason. It its the speed control. Replace it and you are good to go.

log man

mabe i said it wrong, but it is not the fan, all speeds workfine, it is the temp control that is hot or cold at its fullest all the time , no regulation

WestTN

The blend function depends on a position sensor attached to the blend door. It is a balanced bridge circuit. If that sensor breaks you will have the symtoms you are reporting.

technolackey

i have same problem, only its the Fan speed controls, on full on A/C (still workin the get that working) and full blast heat... replaced the whole control assembly with brand new, still only full blast fan works...

Busboy

In your case its probably the resistor block mounted in the heater plenum.

technolackey

hmmm that involves getting to the heater core doesnt it... taking that dash apart scares me.. know any tricks?

rage_blue

thecnolacky- the resistor block has two screws holding it to the heatbox. I belive it is just to the left of the fan on the bottom side of the heater box. two screws and an pug and its out.

JoeCanuck

I will bet that the problem is with the connector between the blend door actuator and the blend door itself.

This is a very common problem and a pretty easy fix.

To verify if this is the problem, look under the passenger side of the dash. The actuator is just to the right of the transmission hump and has a small wire harness connected to it.

To test it, turn the def/vent/floor/ac **** to off. Turn the key to run, (without starting the truck. this will allow you to hear the actuator running).

Turn the heat control **** to full cold. If the connector is broken, the actuator will continue turning in this position.

Next, turn the heat **** to full hot. The actuator will turn the other direction and not stop.

Then turn the **** to the middle position. The actuator will run for a while and then stop. If you move the **** to the left and right, (but not exceeding the 3-9 oclock positions), it should make small steps.

If it does these things, it is definitely the crappy plastic connector between the actuator and the blend door.

You will be able to hear the actuator working and if you look carefully, see the actuator shaft turning.

I don't know what they cost from Dodge but probably not much. I fixed mine with wire reinforcement and epoxy. If it breaks again, I'll probably replace it.

If you want a permanent fix, do a search for, Dodge Ram Blend Door heater fix, on ebay. The add also explains the procedure.

The actuator is held in with a couple of phillips screws. Removal of these screws is easiest with a 90 degree screwdriver. It helps a very great deal if you cut the carpet and padding out from under the actuator. The actuator itself will fall down. The connector will probably stay on the blend door shaft. It comes off with some tugging and spinning with pliers.

The job is a bit of a pain but easily doable in less than an hour.

technolackey

checked the blend door, its fine, can hear the blend door shut away from the heat... i guess i also forgot to mention that only def and floor work, vents do not... thinking a problem in the vacuum lines maybe? the instrementation (*****) panel is new, or at least has been replaced, so its not that...

Busboy

This thread contains two different truck problems. The blend door is related to the original problem. You seem to have two problems. First your resistor block is probably fried, thats easy to replace and will fix your fan problem. Second your vents don't work. That could be tricky. IF there is NO vacuum then only defrost works but because your floor also works you must have vacuum. Ensure that the YELLOW one is installed for the vents actuator. You can see this by looking with a flash light on the drivers side from outside the truck. IF all the lines are on then you either have a bad (leaky) servo, OR the rotary vacuum switch is not the correct one. You must get one from a truck that has air conditioning as the heat only switch is different, it looks the same and will fit but is ported different.