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97 OBS no heat/fan switch stuck on 4


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Hello everyone. New to the MB, couldn't find an answer for my troubles.

 

I have a 97 OBS 2.2 5speed with 197k. This winter i went to the car to go to work in the AM and there was no heat (there had been the night before). The fan does not work, and the fan switch is stuck on #4 setting (high:Flame:). After a while of driving i can feel some transient heat coming out of the vents, but not enough to heat the car. I have checked fuses, although I cant tell which fuse is actually for the heater motor/etc. thinking the fan switch mechanism may just be blown? is there a relay under the hood that i should be checking or replacing? tired of the frosty drives.

 

thanks

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Yea - but his may be sounding like a fan or resistor problem.

 

Also FYI between 95 and 99 they changed the controls visually but I don't know if they are interchangable or not. Realized it when a friend with a 95 needed one and I only have one for a 99 that I can find currently.

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The resistor block is cooked. 4th speed is just a straight connection from 12v to the motor, everything else goes thorugh the resistor block.

 

Just replace that and you will be golden, nothing wrong with anything else.

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Could well be an issue with the fan. Sometimes, the fan will quit working, if it gets gunked up with tree leaves and crap that fall down into the fan from around the windshield.

 

My fan quit, thought the fan had broke, but cleaned out the crap, and the fan motor began working again as good as new.

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OK. so i dove into it this weekend. took the resistor out of my wifes 96 outback (in which the fan works) and plugged it into my car. still no fan. took the blower itself out of my car and plugged it into my wifes car and it worked fine. so its not the blower motor resistor, and its not the fan that doesn't work in my car....its the switch itself???:confused:

 

as far as i can understand, thats the last remaining item that could be the culprit. however, other than junkyards (which i haven't checked yet), i can't seem to find the assembly online or in parts stores.

 

any advice on what it might be other than the fan switch on the dashboard? if the problem were the resistor, the fan would work on #4 setting - which it isn't. when the problem arose one morning the fan switch inside the car was STUCK on the #4 setting and there was no fan at all. the night before the fan was working 100% fine. ideas?

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Derek,

 

I had the same problem on my 1992 Legacy, except that my switch was not "stuck". Are you saying that the fan speed switch worked fine one night and the next morning you went out and you could not slide (turn?) the switch at all? And it is stuck on the highest speed setting? If that is correct, then I guess I would suspect something with that switch itself.

 

However, my problem, after troubleshooting the fuses and the blower relay and the resistor block, turned out to be a bad wiring connection. Search for my thread on this from a month or so ago.

 

Good luck!

 

Mike V.

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Derek,

 

I had the same problem on my 1992 Legacy, except that my switch was not "stuck". Are you saying that the fan speed switch worked fine one night and the next morning you went out and you could not slide (turn?) the switch at all? And it is stuck on the highest speed setting? If that is correct, then I guess I would suspect something with that switch itself.

 

However, my problem, after troubleshooting the fuses and the blower relay and the resistor block, turned out to be a bad wiring connection. Search for my thread on this from a month or so ago.

 

Good luck!

 

Mike V.

 

yes, the fan speed selector (sliding type) was literally stuck on the #4 setting one morning after working as intended the evening before. i shoved the fan speed slider out of this stuck position but its still not working and doesn't slide like it is supposed to. i took the temperature control unit out of the dash to look and see if there was some coffee or something in there, and there really isn't. i'm searching now for a used one at a junk yard but it seems hard to find. :banghead:

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To power the fan, 12v comes from the relay, grounding comes through the switch and resistor.

 

So, just to rule out the relay, check to see if there is 12v on one of the wires going to the fan when the mode selector is on (heat,defrost.....anything but "off")

 

If you've got 12v there, the relay is good.

 

And you've verified the resistor works in the other car? correct?

 

I would assume at that point it is the fan switch.

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To power the fan, 12v comes from the relay, grounding comes through the switch and resistor.

 

So, just to rule out the relay, check to see if there is 12v on one of the wires going to the fan when the mode selector is on (heat,defrost.....anything but "off")

 

If you've got 12v there, the relay is good.

 

And you've verified the resistor works in the other car? correct?

 

I would assume at that point it is the fan switch.

 

 

i'll give this a shot. also, which relay is for the climate control? i have looked at them all (under dash and under hood) and none are labeled as climate control, or fan, or anything. is it somewhere separate from the other relays??

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I would guess the switch is broken. If it was jammed and you forced it to turn, then it probably broke internally.

The switch can be removed from the climate control assembly but it's easier to just replace the whole thing with a junkyard unit. Only takes a few minutes to remove it and you can check the switch for continuity to confirm before replacing.

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I would guess the switch is broken. If it was jammed and you forced it to turn, then it probably broke internally.

The switch can be removed from the climate control assembly but it's easier to just replace the whole thing with a junkyard unit. Only takes a few minutes to remove it and you can check the switch for continuity to confirm before replacing.

 

continuity can be checked, just via multimeter?

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At the risk of insulting, a continuity test determines whether a connection is "closed" (no resistance; zero ohms) or "open" (infinite resistance). Multimeters typically (always?) have a ohm meter function, so, yes, a multimeter will test continuity.

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At the risk of insulting, a continuity test determines whether a connection is "closed" (no resistance; zero ohms) or "open" (infinite resistance). Multimeters typically (always?) have a ohm meter function, so, yes, a multimeter will test continuity.

 

not insulted, and i get what a continuity test does. i meant, how do you perform the continuity test on the switch itself? where on the switch itself should i be touching the probes to do the test. pardon my ignorance, i get some of the basic concepts, but i've never done it before so i'm trying to gather info before i go get a meter and test away.

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If I were going to test the fan speed switch for correct functioning, I would first locate the plug connector for the switch. Then with my wiring diagram at hand, I would verify continuity (or lack thereof) between the different pins in the connector (verifying that what you get is what the wiring diagram indicates that you should have).

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Right, using a multimeter you can check for resistance across the terminals on the back of the fan switch. You'll either get 0 resistance or infinite resistance. Infinite resistance meaning the switch circuit is open, thus no power is able to flow through, thus fan doesn't work.

 

The harness plugs straight into the back of the switch, and the large black wire is the ground.

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