Jeep Cherokee 98 A/C malfuntion

Maintenance/Repairs
1

I own a 6 cylinder Jeep Cherokee 98 that drives great and is in top condition for a vehicle that is 10+ years old (I’m a Jeep enthusiast).

The A/C control panel is the vacuum-controlled type and it will ONLY work when the dial is set to the maximum output. The positions go from 0-4 (so only 4 works). It sends out cold and hot air ok. It also delivers it well depending on the position (dashboard, feet or both).

I’ve looked at the fuse and its ok.

I used to have a Cherokee 94 that experienced the same issue.

Has anyone ran into this before and fixed it, and how?

Thanks

2

The blower only operates when set at full speed? You get cold or hot air out at a lower speed when the vehicle is moving fast enough? It is probably the blower speed control resistor assembly. A resistor has burned through. The blower motor might have caused it by dragging and causing the resistors to heat up too much.

3

Thank you for correctly naming the part for me. The blower speed control on the dashboard will only work when set at the maximum speed (the control dial has only positions 1-4). When the car is moving fast enough I notice that some air comes through the vents if the blower speed control is set to positions 1-3 but it does not turn the blower on, it will only turn on at #4 which is the maximum regardless of the speed of the vehicle.
I actually replaced the dash control assembly with a salvaged part, but had the same result once hooked up and connected. I’m hesitant to buy the part at a dealer and get the same result.

4

This is a regular problem with cars. There are a set of three resistors that control the speed of the fan. The tend to blow out starting with the slowest speed to the highest. The highest does not have a resistor.

There are two possibilities.  Simple resistor failure which means simple replacement of the resistor pack or replacement of the resistors, assuming you are into doing those things.  

 The second possibly is a blower fan motor that has worn bearings and is causing the resistors to go out.  

  You can try just replacing the resistor pack and if it goes out again soon (usually slowest speed first) then you will know it is time for the motor as well.  Or you can just replace both at the same time. 

   I believe it is not too hard to get to those parts on your car so you might want to try the resistor pack first.  If I am wrong about that and you spend a lot of time or money getting to the resistors, it might be a better idea to replace both while you have already done most of the work.  Check the prices and make up your own mind.
5

I’ll certainly get both parts and replace them. I appreciate all the input!

6

It is the resistor, and it is not expensive. I have only replaced 1 or 2 in 60 years of driving and the Blower motor was OK.

7

If you have an ammeter (multimeter) check the current drawn by both the old and new motor at full speed before you replace the resistor. Watch the spike when it starts up and where it steadies down to. (An analog meter will be better for this). If they give you similar readings, the old one is O.K. The meter will only cost you a few bucks and will come in handy. Just be sure it will handle current above what the fuse for the blower motor is rated.