1984 Jeep XJ Pioneer-defrost heat but no fan

Air conditioning and heat controls, doors, and fan work fine. On defrost, I can feel the heat coming out of the windshield vents softly but the fan won't come on. Ideas?

obxxj said:

Air conditioning and heat controls, doors, and fan work fine. On defrost, I can feel the heat coming out of the windshield vents softly but the fan won't come on. Ideas?

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Does the fan work at other setting or speeds ?

If it's just fan speed the resistor is probably the cause. I believe its the same 84-96 and easy to get to from the passengers side.

If the fan works at other settings my guess would be its in the heater control. Which it a bigger problem because the early Xj controllers are unique to the early years (84-85 only?).

When I got my 85 Xj it was in winter and the blower switches didn't work at all, I pulled the blower motor which was bad but had to match it up at auto zone because the catalogues didn't show those years. Sadly the heater controller (dash switches ) was burnt out too , the fan part of it was shorted out. Took some time to locate another heater controller assembly so I ended up bypassing it and setting up a switch and running a wire from the battery.

Edit as I recall the dash actuators which control the setting between vent and defrost is actually vacuum so if the heater controller is burned out that part will still work.

The fan does work at other settings and all three speeds work. Just no fan at defrost.

Since the fan works it's not the resistor.
My only guess is a switch inside the heater controller is bad or maybe a lose plug.

You might be able to pull it out and clean it if it's not burned out, it is over 30 years old now maybe it is gunked up.
I never tried to repair the heater controls maybe someone who has experience can give some advice.

Thank you Green Mesa!

It may be a simple fix of cleaning it up.
Thinking about it you have two extremes off and defrost .

Hang on I'm home right now, I'll get you a picture of what the switch I think is the problem.

Top pic: off


Bottom pic : defrost

I have my radio out as part of the great 30 year upgrade/ rebuild that'll be in full swing this summer (hopefully) , so you can clearly see the switch in the center of the controls. I'd pull it just enough to check the plug and clean up contacts. But the center switch might be bunt out too. If you have to replace it, going to be hard to find its 84-85 only. At least the whole control is. I don't know if any of the switches are the same after 85. It's the same basic design so maybe. But I've never had my newer XJs ac controls out and the old XJ I've fought to get back to working normally. Also mine is the non ac version so it was particularly a PITA to locate parts for.

For a used search try car-part.com for used part search not all junk yards are on it but more than enough to find the part you need.

Hope the pictures upload , first time trying this with tapatalk

Thanks Green Mesa!
Guys like you are why this webpage rocks!
David