Ok here is the deal....my heat used to work. I own a 91 740 turbo with 125k on it and the heat used to work but only when i turned it to the highest speed. Now it does not work at all. What could it be? I checked the fuses and they are fine.

 

OK cold air comes out?

Or you have no fan at all?

If you have cold air only coming out then open the hood and look where the hoses go into the car.There should be a Valve controlled by vaccum.See if it is working properly.

 

no fan at all

 

Well if the resistor is bad then you should still have high fan speed.High doesn't go through the resistor.
Do you have ECC or MCC?
Hint Ecc will have an auto setting on the temp and fan.

 

Im not sure what you mean by ECC and MCC?

I read that the resistor could be bad if the fan only worked on the highest speed then just quit.

 

Colgate,

ECC = Electronic (automatic) Climate Control
MCC = Manual Climate Control

 

Look at the fan switch and see if it only has 123 Etc or does it have AUT then some fans speeds.

The high fan speed is direct 12volts from the switch.

Do you see where im going with this?

Im thinking maybe a bad switch.

 

The switch has 1, 2, 3, 4, and 5 being the higest

 

If it is a bad switch, how will i know? Is there a way to test this?

 

also, i took the blower motor out from the right bottom on the passenger side and it had water in it and also looks corroded.

 

Sorry to be a pest, but i just took the blower motor out and got rid of the water in it and cleaned it up some pluges it back in and once again it works!!! But only on the higest setting *5 in this case...so im going to put everything back and see how long it lasts. Any ideas about what could be wrong? Switch possible?

 

Now that you have atleast one fan speed that works then you can test with a meter for Voltage at the motor.
If you have no voltage at the motor then the resistor is bad.That is at the lower fan speeds.

Also you might want to check the A/C drain and make sure it isn't clogged backing the water into the box.

 

Correct, i looked for the a/c drain but i couldent find it...where would it be? Somewhere on the fire wall i know but where? I think the a/c/ drain is cloged and thats the cause of my problems, and i only know now because we have got heavy rain for 5 days and im in NY. Thanks

 

Yes the A/C drain is in the firewall.Find the A/C lines at the firewall.Then follow the firewall straight to the ground.On the way maybe about a 1ft to 1ft and a half you will see a black thing coming out of the firewall.That is the drain. Sometimes people also put a black hose from the drain to the body.

 

Thanks again, what would i do with out you guys