cooling fans

[hoover]

Hi, before I take the fan relay apart I'd like to ask for confirmation of the following symptoms I'm getting------as soon as ignition is turned on the fans start,(fast) I have unplugged the thermofan connector (ign on) fans are still running(fast). Linked terminals 2 &3 on thermofan switch connector (ign off), fans run but fast. Looking like relay, your views please.

[9FF]

Relay is a quick swap to confirm but my educated guess is if your fans are always running fast your puck resistors are toast.

[hoover]

I've not got a spare relay to try, and please explain more about these resistors.

[9FF]

I've not got a spare relay to try, and please explain more about these resistors.

Two large ceramic "puck" resistors are located behind the glovebox or under the fan cowl in the engine bay on later cars. They control fan speed on both the fans. They either work (fans run at low and high speed) or they don't (fans on high speed only).

[hoover]

Thanks for that, will check them out before going further.

[ernie9944]

Originally Posted by 9FF

Two large ceramic "puck" resistors are located behind the glovebox or under the fan cowl in the engine bay on later cars. They control fan speed on both the fans. They either work (fans run at low and high speed) or they don't (fans on high speed only).

+1 (see pic of how bad the connections can corrode ).

[hoover]

Thanks for the picture, very thoughtful of you

[9FF]

Thanks for the picture, very thoughtful of you

You would have got one from me but mines an 86 with the resistors behind the glovebox. If yours is the same you have to remove the glovebox and get into some extreme yoga position to access them GL

[hoover]

No problem, I'm grateful to you for the location info you posted, I have an '89 so a little later.

[CatsEyes]

Originally Posted by 9FF

You would have got one from me but mines an 86 with the resistors behind the glovebox. If yours is the same you have to remove the glovebox and get into some extreme yoga position to access them GL

Hey 9FF,

I have exactly this problem, on my 1986 RHD (Euro-spec) 944.

There is a clicking noise behind the glove box (on the left-hand side of the car), when the fans succeed or fail in going to low speed.

I'm presuming this is the same layout as for LHD cars, but on the other side.

Do you have any more precise information about where the 'puck' resistors are? Is there a diagram somewhere? Perhaps my yoga skills are wanting, but I'm struggling to locate them...

Thanks,

David

[9FF]

I don't know for sure where they are on the 86 RHD models but I will guess they are somewhere under the dash attached to the firewall. They moved them from inside the car to under the hood on 87 models. Search with a bright flashlight for this:

[hoover]

Well I've been searching all morning for mine! They're not under fan cowling despite being a post '87 car. Maybe the s2 is different, I presume they must be fitted to this model? Checked under the glove box just in case. It's right hand drive so will start looking at the other side.

[CatsEyes]

[QUOTE=9FF;6915777]I don't know for sure where they are on the 86 RHD models but I will guess they are somewhere under the dash attached to the firewall. /QUOTE]

Thanks, 9FF.

The sound is definitely coming from behind the glovebox. But, as you say, it's tight in there. Not easy to see them.

I'll have a better look tomorrow. If I dig the little critters out, I'll take pics for the RHD folks.

[CatsEyes]

Found 'em.

9ff's intuition was right.

On RHD cars (at least '86 and earlier) you'll find them on the driver's side, under the steering column, on the right hand side (actually to the right of the firewall).

Can't find anything wrong with mine: they look almost factory.

Ah well, more troublshooting...

[Guest765]

That clicking sound by the glovebox is your relay 'firing', for lack of a better term. Everything inside on a rhd is reversed but under the hood the relay/fuse box is still in the same place.

[hoover]

Updating this thread to inform that an '89 Rhd s2 (which Im' calling a late car) car also has these resistors to the right of the steering column underneath. The wires on mine look pretty sound, wondering if the actual resistors are dead. Is there a test?

[Rasta Monsta]

Originally Posted by hoover

wondering if the actual resistors are dead. Is there a test?

Well, you could always check the resistance.

[hoover]

Originally Posted by Rasta Monsta

Well, you could always check the resistance.

Well I suppose I asked a silly question

[CatsEyes]

Originally Posted by fwayfarer

That clicking sound by the glovebox is your relay 'firing', for lack of a better term. Everything inside on a rhd is reversed but under the hood the relay/fuse box is still in the same place.

Thanks, fwayfarer.

I'd already replaced the relay, though, so this is puzzling. Maybe I should check the wiring below.

[bleu951]

Hoover, your cooling fan relay is bad. The resistors only come into play when the relay wants the fans to run at slow speed. If you want to go through the system, I have created a diagnostic procedure that is included below.

During normal operation, and you have the factory rated thermostat, the coolant temperature gauge should read at or near the lower white line (80 degrees C) and will creep up to the mid-point between the upper and lower white lines when sitting still in traffic. The upper white line represents 100 degrees C. If the temperature normally runs above the mid-point, you need to investigate immediately.
There are several temperature ratings of the thermo switches, so it is hard to say at what point they should turn on for your car. If they are not both running at high speed when the temperature is above 90, you might have a problem.
The fans are controlled by the cooling fan relay which is in turn controlled by the thermo switch, and the a/c system. Whenever they are closed, both fans should run at the same speed at the same time. If only one is working or you only get high speed operation, there is a problem.

You should always have power available to the relay, so the fans can run at any time. Remove the cooling fan relay. It is the large rectangular silver relay in the back of the panel. Check the diagram on the fuse panel cover for the exact location. All of the following checks can be made at the fuse panel. You will need a bright light to see the markings on the fuse panel.

1. In the Bosch world, a terminal designation of “30” means it is un-switched battery voltage. Check for voltage at positions 30 M1 and 30 M2. You should get 12v + at both positions. If no voltage, check the wiring from the battery, the connections to the fuse panel, and the fuse panel itself. You will have to pull the fuse panel up, but disconnect the battery before messing around under the fuse panel.

2. Check for continuity between ground and the temp switch positions "TS" and "TF" on the fuse panel. If you have continuity, the thermo switch is calling for fan operation. If the car is cold, the thermo switch is bad.

3. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.

4. Connect the jumper between M1 30 to M1, the drivers fan should run at high speed. If the fan does not run, check for voltage in the connector at the fan motor, if you have voltage but the fan does not run, replace the fan motor.

5. Check the passenger fan by connecting the jumper between M2 30 and M2, the passenger fan should run at high speed. If not, the same drill.

6. Next connect the jumper between M1 30 and V1, the drivers fan should run at low speed. If not the resistor or wiring is bad. Check for voltage at the radiator fan connector and then check the resistance across the resistor.

7. Next connect the jumper between M2 30 and V2, the passenger fan should run at low speed. If it does not run, check the wiring and resistor.

If the car is still running hot and the fans are working properly, you have other issues, like a clogged radiator, water pump failing, air bubbles, bad thermostat, or a bad head gasket.

The other positions on the fan relay are:

X = battery power to the logic board in the relay
31 = Ground for the logic board in the relay
AC = AC freeze protection switch