bajabluejay

Peculiar situation on my new '86:

No low speed fan.

Completed troubleshooting:

Jumper on 2-3 of thermofan switch, nothing

Resistors ~0.9 Ohm, put new spade connectors on some of the more corroded wiring going to the resistors.

Up at the relay box:
M1-V1: 1.4 Ohm
M2-V2: 1.5 Ohm
Jumper on 30M1-V1: Low Speed Fan works
Jumper on 30M2-V2: Low Speed Fan works

Swapped with my '87 relay, 2-3 jumper does not work

AC Switch does nothing. No high, no low. The system is definitely empty, the compressor bearing is rattling like crazy, and it looks like the compressor clutch pigtail is disconnected. Would an empty system cut out the low speed operation?

Stumped!

V2Rocket

low speed should come on based on the radiator switch.
high speed is from a high-temp condition at the rad switch, OR the AC is turned on.

if jumpering the relay pins makes the fans work, but jumpering the switch doesnt, suspect either the switch or relay to be faulty.

StoogeMoe

See my thread from a long time ago how it works

Click here

Jumpering M1 to V1 and it works tells me your relay is shot. Do the fans work if you ground TS? If no, then your relay is shot.

BTW, you are incorrect V2, AC turns on the slow fans, not high.

V2Rocket

...not on my car...
(currently using 100% oem 944 fan setup)

StoogeMoe

You have an early car? The OP has an 86. Different as you know.

If not, then your car is not normal!

V2Rocket

clark's details the early model fan function correctly...
though it appears your explanation for late models is also right.
wonder why they changed it...would think "AC on =fan high speed" would be better.
http://www.clarks-garage.com/shop-manual/cool-01.htm

bajabluejay

I swapped the relay from my '87, and no dice.

The coolant fan relay box gets 12 volts at terminal "X" with the key on.
The coolant fan relay box has a ground at terminal "31" with the key on.

Help!

bajabluejay

Well, maybe it was the relay fan after all...