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post #1 of (permalink) Old 12-21-2000, 10:35 PM Thread Starter
 
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Is my heater switch is dying slowly ?

Hello All

A few months ago I noticed the heater switch's highest setting wasn't as fast as it used to be, I put it down to maybe it was clogged with leaves. While Xmas shopping today I noticed my heater fan slowed down again. I also noticed it only runs on lowest or the next speed up.

The fact the fan runs at all, on these two lowest speeds, makes me think it's the switch not the fan motor....right ? If so, who carries one, just the dealer ? and how much is it ?

Thanks and stay warm everyone

Malcolm

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post #2 of (permalink) Old 12-21-2000, 10:52 PM
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Re: Is my heater switch dying slowly ?

Right: not the motor. The switch does sometimes burn out, but, more often, the resistors burn out. They are accessible from the engine compartment on the passenger side just inboard of and below the fan motor. There is a plug with about 5 wires, and 2 screws hold the plate in the duct. Both the switch and the resistor plate are probably dealer/junkyard items.

Steve
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
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post #3 of (permalink) Old 12-21-2000, 10:58 PM Thread Starter
 
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Re: Is my heater switch dying slowly ?

Thanks Steve

So which do you figure it is ? If the resistor is burned out, wouldn't the fan not work in any speed ? Or do you lose different speeds slowly with a faulty resistor ?

Thanks again fer such a quick reply, I'm going into town tomorrow so I want to get the part, get the booze and get back out of town before they let the commuters free shortly after lunch onto the roads.

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post #4 of (permalink) Old 12-21-2000, 10:58 PM
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Re: Is my heater switch dying slowly ?

Last year I replaced the switch in the dash on my 80, and before I had Off, Low, Med, and High. With the new switch there is only Off, Low and High. Also I noticed that there seems to be another fan that comes on when I turn on the A/C. There is no A/C on the truck but there is a spot on the switch plate. Anyway I think there are dif switches for dif applications. Later

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post #5 of (permalink) Old 12-21-2000, 11:12 PM
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Re: Is my heater switch dying slowly ?

There are several resistors on the plate; the switch connects one or more at a time to cause the fan to run at different speeds (except Hi: no resistance). If one resistor or switch contact burns, you'll lose only the speed that used the burnt element. You won't know if it's the switch or the resistors until you pull them and look.

Steve
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post #6 of (permalink) Old 12-23-2000, 07:54 PM Thread Starter
 
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Re: Is my heater switch dying slowly ?

Thanks guys

Got the new switch in and got high and 3rd speed back. The parts guy here is really knowledgable and used to drive a Bronco so he's a wealth of info. He told me that because I had the lowest trickle speed and 2nd speed, but not the 3rd speed or high, that it was the switch. If it had been the other way around, it would have been those resistor blocks like you guys suggested.

Interestingly he said the 5 wire female plastic socket that plugs into the switch would probably be burned out and I should buy a replacement one and crimp it into replace the stock one.

Well he was right it was charred, but I was still able to plug the socket into the new switch and fire up all four fan speeds, and at -31 with the windchill this morning, that was good enough for this guy. Boy Henry's engineers don't exactly make it a piece of cake to get at that switch !

Warm again, thanks guys

Malcolm

"Well it's 40 below, got a heater in the truck, so I don't give a f#@k and I'm off to the rodeo !"

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