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climate control unit 700 1990

posted by crow1 on Fri Dec 29 02:30 CST 2006
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last visit: Tue Nov 20 01:00 CST 2007

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I was trying to find a rattle in the dash. I removed the bezel and 4 screwa to the climate control unit (manual one with fan switch and slider controls). Pulled the climate unit out enough to look behind for source of rattle (did not find anything). Put everything back and now the fan does not turn on. Checked the fuse and it is good.
Any suggestions? It is cold here and of course my daughter will not drive it with no heat!

thanks in advance.

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climate control unit 700 1990

posted by Kurzweil on Fri Dec 29 03:08 CST 2006
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last visit: Tue May 1 00:41 CST 2007

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Gosh, if it was working before than it HAS to be the wiring plug to the switch. since none of your heater speeds work, it has to be the wire feeding power in. You can use a meter or make up a little test jig with a auto lamp socket and working bulb. Hook one wire to any ground and use the other as a probe. Bulb will light when you touch a hot wire. You can poke into the connector. Just be sure you don't ever hit two at a time (if you do, it will just blow the fuse as a worst case and run the fan as a best case). If you find a wire that is hot (switch on, of course) you should be able to jump that wire to one of the others and hear the fan start up at some speed. That would indicate a switch failure - - not likely in your case. This is general knowledge based on only seeing the back of that panel one time. Most of the controls (sliders) are purely vacuum.

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climate control unit 700 1990

posted by crow1 on Sat Dec 30 01:45 CST 2006
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last visit: Tue Nov 20 01:00 CST 2007

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finally found the cause...unplugged ground.
go figure...try to fix one thing and end up spending hours fixing what I messed up.
oh well

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climate control unit 700 1990

posted by crow1 on Fri Dec 29 06:52 CST 2006
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last visit: Tue Nov 20 01:00 CST 2007

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thanks.
As per your info,
I tested the fan. It works fine.

The switch cuts power on and off to the relay and the resister pack so the switch is working.

The resister pack has power when the switch is on to all 4 connectors...dont know if that is right or not.

The relay has power on the black at any switch position. The other lugs power off and on dependant on switch position.

The relay makes a buzzing sound when the switch is in the highest position and the test probe is touched to a positive terminal at the relay. This car has not had the highest fan speed in years. Maybe a clue?

I tried jumping some leads but could not make the fan come on.

It seems logical that either the relay or the resistor pack has gone bad (or both). Sort of bothers me that it happened when the climate control unit was out of the dash. Gremlins, I guess.

thanks
any other suggestions would be appreciated.

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