CorsePerVita

sounds like a pretty awesome tool!

roman944

the thermofan switch is new though, that was the first thing that we did

my dad and my brother took the fan relay (#1 on the panel) apart, and found that at one of the connectors inside, if you have access to one - then when the connection happens, both sides connecting have these little pads - and on one connection this pad is churred/half-worn

so they are thinking that this may be the culprit ... maybe

still going to check and try to bleed it some more to make sure that everything is right

I'm sure once the car is on the road (with A/C thing removed) + fans (somewhat) working + cooler temperatures, it should be fine

but I'm in no rush, I got time to do everything right

I also just may try and see if there is a vacuum bleeder available from local people or how much it is to rent one out ...

roman944

oh btw, I have one of these "multipurpose" relays around, they are advertised as good for anything from fans to headlight motor, think it would be safe to try it out on the fans?

smokin_944

Holy crap! I'm out getting snapped up watchin NFL football while the man is in trouble!! Oops!! On the early car, if the slow speed fan doesn't function, chances are that the resistor side of the circuit (slow speed) isn't working. You are lookin for a rtan colored resistor that looks like a hockey puck. The connections could be bad. Let me explain. When the temp hits a predetermined point(depending on which thermal switch you have), this triggers a parallel circuit on the cooling fan circuit that gets the fan to turn on in slow mode. This happens cause the power is fed through a resistor that cuts the power supply down (in simple terms). Once the temp gets to the critical point (high temp), through a parallel circuit in the coolin fan relay, the high temp trigger bypasses the resistor and both fans go on at high speed. IF the slow speed fan fails because nothing is getting to it (electrically) this means that the connections and/or the resistor is at fault. The only other possibility would be that the cooling fan relay is toast. You have to check these options and get back to me.

CorsePerVita

i shot him a link to the wiring diagram on clarks garage and gave him some info on a few tests. hopefully it'll be easy for him to test. a good multimeter is worth its weight in gold. i also gave him some tips on testing out the relay and bypassing using the A/C method. i remember the first time i saw a wiring diagram i thought i was looking into the motherboard of the starship enterprise. now they don't scare me so much.... rewiring my 914 from bottom to top taught me that one.

roman944

ah! your PM mentions that if the A/C is on, it over-rides everything and both fans should run ... they don't ... relay issue?

shiners780

I've got time on Tuesday, if you want I can bring over my pressure tester and some known good relays. Just let me know.

CorsePerVita

I like Shiners idea! That'll make it EASY to tell.

From what I can tell, it sounds as if we may be encountering more than one issue.

- Driver fan doesn't run in low speed at all (this would be the resistor circuit, and would need to be tested to ensure there is power to it and that the resistor checks out)
- When "HIGH" temperature kicks in the fan turns on with high speed (normal)
- When A/C is turned ON, fans do not turn on? (neither of them)? even in low speed or high speed, if the lowspeed circuit was working, turning A/C on would get the fan running. Potentially a bad A/C relay could also cause this as well, since it should at this point kick on both fans. If nothing then check your fuses, if fuses are good then it lies elsewhere (bad fan, bad wiring)

If you look back at the wiring diagram, you'll see where the air conditioner relay directly functions the driver side once it's turned on. Then determining the relay or circuit(if you're in slow speed mode or high speed mode) the fan should turn on. If your low speed circuit is fubar (as it never runs low speed as it is) it won't work. If your relay is fubar as well then it wouldn't turn it on in high speed. The other culprit would be fuse 3 or the A/C relay altogether. But if fuse 3 was bad, your driver side fan would never turn on as it is.

Clarks garage covers most of the possibilities, but once you get into bad relays/switches/wiring you can have a really strange variation of issues and symptoms. Unfortunately with wiring the easiest way is to check and find out what /is/ working and start testing from there working your way through a circuit till you find the culprit.

The low speed circuit most definitely is it's own thing, if you know from fuse 3 things are working, then my first check would be contacts and the resistor there to get that going again.

roman944

after a little cleaning, when engine gets up to the temperature (thermostat opens?) both fans kick on

but it doesn't happen until 3rd mark on the gauge

I'll have to try the car out on the road and see what happens maybe

Jim - sent you a PM back!

also, right now I can't remember which thermo-fan switch I went with, I think it was the one from Rennbay, but I don't know if it was the 87", 92* or 72* or w/e ... if its the 92 one or something high like that, then that may explain why the fans kick on THIS late, right?

CorsePerVita

92C is 197F - which would be near the 3rd mark as 3rd mark on an early car is 97C. 75 is low temp, and the 80 is OEM normal temp.

http://clarks-garage.com/shop-manual/elect-19.htm

roman944

do you happen to know if the fan switch is stamped with the * or not?

just hit me now after reading back a bit, that I don't know what temp thermo switch I have right now ...

CorsePerVita

I have a new thermoswitch at home I'm installing in my car this week, i'll look on it when i get home to see if it's stamped on it. i know it is on the thermostats, not sure on the switch but i'll check once i find it..

smokin_944

If you are talking about relay #141 951 253 B it IS the cooling fan relay on Series 1 cars!!!

smokin_944

Yup!

smokin_944

Right again Roman... cooling fan relay probably...