98 XJ Heater Fan Control Operates on "4" (High) Only

The heater fan control knob on the dash now only operates on "4" (highest speed). I know it's simple enough to pull the dash bezel off and replace the control, but before I order a new part, my question is this: Before I go to the dealer or boneyard to find a new switch, could anything else be causing the problem?

Thanks,

Mark '98 XJ

Reply to
M. E. Bye
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If it only works on high then the resistor pack is probably toast. I am betting the dash switch is fine. If the resistor pack is toast then you should also change the blower motor out too. It probably caused the resistor pack failure. Just changing out the resistor pack will probably be cheaper but it will fry again. KH

Reply to
Kevin in San Diego

What Kevin said. Take a look at the connections on the resistor pack if they are cruded up give them a good clean and see if the fans speeds come back, sometimes its just dirty. If not the resistor pack is gone.

Snow...

Reply to
Snow

Reply to
L.W.( ßill ) Hughes III

I don't have any experience of Jeep resistor packs, but others (like Saab) have three large resistors (that rarely go) and a thermal fuse (that often goes). The thermal fuse is an inexpensive item and a replacement can be crimped on. Available from Tandy/Radio Shack.

The Saab had the problem since the resistor pack was located in the airstream for cooling, but in position one there wasn't positive airflow before the pack got too hot. After changing a thermal fuse in one I found that by switching the fan to max and then to the desired speed the thermal fuse didn't blow again.

I don't know how or if this applies to the Jeep.

Reply to
Danny

Reply to
mic canic

In the Saab design, since each speed has it's own resistor (apart from full speed) it's unusual for the resistors to all go. There is usually a thermal link that blows and can be replaced. Note: crimp, not soldered.

Reply to
Danny

The point is, that if the resistor blows then something is probably wrong with your fan. Even if the Jeeps whole resistor pack magically disintigrated, its a cheap easy part to replace. What caused the failure is the issue here. KH

Reply to
Kevin in San Diego

FWIW my old Ford Escort ('91) was the same way.

On that one, though, I had the connector contacts corrode instead of the fuse blow. The replacement I left hanging so it couldn't collect water again, but during the summer my dad forgot and left the blower on too long and blew the fuse (he was borrowing the car then). He wrapped a bare piece of wire around the fuse to bypass it, but that gives no protection against overheating and starting a fire.

-D

Reply to
Derrick Hudson

Not necessarily. In the case of the Saab design, the resistors are cooled by air movement through the blower assembly and in slower settings there is insufficient airflow in the short space of time it takes the thermal fuse to overheat. Starting the fan on full and then turning it down to the desired setting allows positive airflow to be established before the resistors are used.

Reply to
Danny

Reply to
mic canic

Yeah then charge again for replacing the fan..

Snow...

Reply to
Snow

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