this is for my 99 s10
it has 4 fan speeds.the first 3 work but when i put it on the highest the fan just shuts off.
i changed the relay,resistor and the heater control and still nothing
any ideas?
i heard about something in behind the deck,its some kinda relay or something but i dont know what its called
ive tried s10 sites but no help really there

 

well, sounds like your switch to me but I'm no expert. before you real far you could check the ground. used to have an 86 firebird & the blower just quit; repair shop ran a new ground from fan box to the sheet metal under the hood and the fan started working. same car and headlight motor also went out. a buddy ran a new ground & the fan moter started working again. probably not your problem but might try it and eliminate a semi-bad ground wire from the problem set.

 

The high speed blower position uses a different 12V source than the three lower speeds. Start at your blower motor, you should have two connections, one black (which is the ground) and the other is Purple? (purple on camaros) and trace back to the blower motor relay in the engine compartment. You should find a RED or ORANGE wire on the relay. Trace this in the engine compartment. Most likely the fusible link in the red wire is blown.

One way to check is to pull the blower motor relay and put a voltmeter between the terminal for the red wire and ground. It should be hot all the time. If its dead then the link is gone or the wire is bad from the relay back to the link.

Let us know what you find...

Dave

 

I second 82 crossfire Z28. I am relpacing one tomorrow on my 84. I have all other speeds but no high. When It started I had none.

I wired the motor to the bat and it ran. So then I replaced the switch and it worked no high though, Ordered the part SUN and will put it in tomorrow.

 

on the back of the fan speed switch there are 4 wires pluggin into it.does each wire act as a power to each speed?

 

Take a look at the wire diagram at this link...

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

you want to look at Fig. 21, in the top right side.

Three of the four wires power the blower motor at Low, M1 and M2 speeds. The fourth wire energizes the blower motor relay for HI speed. The relay contact provides power to the blower motor at high speed via a direct connection to the battery/alternator.

Hope this helps

Dave

 

Like 82 and OS3 said check the relay. You can look at the switch as long as you want unless you want to fix your issue. You will MORE THAN likely find a bad RELAY