The blower switch on my 87 S4 only works in the third and forth position. The fan does not come on in the first and second position. Is there a fix or do I just need a new switch.
Thanks

 

You probably need a new blower resistor pack.

You can take it out and attempt a repair first (under cowl - through intake plenum wall).

You can also check the switch function there on the connector...

Alan

 

Thanks Alan
I will do a search and find out how to remove the consul to check the switch first.

 

Its easier to test the switch from the blower motor resistor pack end - trust me here - far easier.

Blower pack (if original; '87 module)

Pin 8 - always powered with HVAC on (slowest speed - speed 0) (this is also connected to Pin 4)
Pin 1 - Speed 1 (+ on with all other higher speeds too)
Pin 5 - Speed 2 (+ on with all other higher speeds too)
Pin 7 - Speed 3 (+ on with all other higher speeds too)
Pin 6 - Speed 4

Pin 6 connects to the blower motor directly (and is also connected directly to pin 2 on the resistor pack)

Pull off the connector and probe the pins in the connector to test...

I think you will find that the switch checks out just fine - they very rarely break. The resistor pack is a different story...

Besides even if the switch is full removed from the circuit - you should still get the blower motor powered all the time on the lowest speed via the resistor (note there is no 'off' seetting on the switch - "0" is slow - not off) - since you don't get this (I assume ?) the resistor must have a fault - so either you have a fault on the resistor pack or a fault on the resistor pack AND the switch - my money is on just the resistor pack.

If so evaluate the resistor pack - there should be 'continuity' (low resistance values ~ a few ohms each) all the way from Pin 8 -> Pin 1 -> Pin 5 -> Pin 7 -> Pin 6.
I'm guessing there won't be at least between Pin 5 and Pin 7 (maybe more)...

Alan

 

I had this same problem a few years ago and everyone said I needed a resistor pack. Replaced it but didn't solve the problem. After much digging and taking things apart, I finally found that one of the pins on the blower switch plug on the side of the head unit was melted and had lost contact. Cleaned the pin and socket and all was good. I couldn't find where anyone else on RL had had this problem, but worth checking.

 

If you bench test the resistor pack be careful it gets freakin hot.

 

But not if you test it with an ohmmeter...

Alan

 

Good point. I can't remember exactly why I was testing it under load but damn it hurt.