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Where's the Air?

OK. I think this is an easy one.



2003 Jeep Liberty. 87,000 miles.



I have an interesting problem with my climate control system. I turn the dial to get the fan going. When I have it set to 1, 2, or 3, the fan doesn’t run. It doesn’t go on until I turn it to 4 (full blast)



With winter coming on, I want to have my climate control system in working order. What’s the matter with it? Can i fix it myself?

Either a fuse or bad resistor. If the resistor is fried then you might consider the possibility that the blower motor is failing.

A failing blower draws more current than a normal blower and this translates to more heat.
Since the resistor runs red hot anyway that extra current could be pushing it over the edge

An ammeter can be used to check the blower motor current draw on the high position. If the current is up in the 20 amps give or take range then the blower is failing.

Chances are the motor is fine, there is a variable resistor for the fan speed control that needs replacement. It should be pretty easy to fix, ask for one at the parts store and they can tell you where it is.

I Agree With Your Recommendation. Current Draw Should Be Checked Before Replacing A Resistor (Unless It’s Really An Easy Location And The Part Is Really Cheap And You’re Feeling Really Lucky).

I’ve wrestled resistors into tight spots only to have the blower run fine on all speeds and then blow the new resistor in a matter of days or weeks. Then it’s motor time, anyhow.

A failing motor is definitely a prime suspect in a failed resistor.

CSA

You have a resistor pack, usually two or three resistors. If the other speeds failed all at the same time, then the resistors themselves are probably good. A run on the circuit card probably opened or the main supply pin burned up.

If you blower motor runs as fast as it always did when on high, the motor is probably good. If it drags on high, then it could have a dry or bad bearing. They have designed these motors to be not repairable these days.

Some resistor packs are easy to get too, but most aren’t. I don’t know about yours, but it should be located just behind the fan speed switch.

The Chrysler Resistors I’ve Replaced Have Been Located A Distance From The Fan Switch, Nearer The Blower Motor, Mounted In The HVAC Ductwork, In The Slipstream Of Air That Moves Through It.

Usually they’re mounted with two screws and have a small wiring harness plugged into it.

I agree with the possibilities you present, but also, I’ve had all speeds except high burn out simultaneously when the resistor failed and I’ve had motors that seemed to run fast, but must have drawn more juice than normal.

CSA

It appears this resistor is behind the glove box. Measuring current draw is a good idea. It is currently drawing less amps than the fuse can handle, would that spec be in Chiltons? Tutorial for Mr. Nantuckett if needed.