How did you guys hookup your electric fan wiring? I know there is a fan relay in the stock Merkur wiring harness but it is activated when the A/C is turned on. I need to know how the electric fan and all the other stuff are run. Is there a switch sensor on the block that just grounds the curcuit making the fan come on? Please enlighten me. Thanks for the help.
In the tan car I have a switch under the dash where the right remote mirror control goes (until I install my sport mirrors) and a relay under the hood. In the orange car I used the stock fan with a radiator and shroud for a 2.3 with a/c.
Bill
I would recommend using your own wiring and switch, I had an SVO that after 3 trips to the dealer, the fan still never turned on right AND my Turbo Coupe donor car also had some kind of modification to the fan wiring when I got it, that was enough convincing for me.
While parting out a 87 Turbocoupe, I traced out all the wires. The 87 TC has two electric fans and they worked fine. The computer supplies the ground to the control relays for both the primary and secondary fans. I assume the computer uses its "engine coolant temperature sensor" to determine when the fans are needed. Bypassing this computer control, is a A/C pressure switch that turns on the secondary fan by grounding its control relay.
These are fairly high current circuits and a dirty or deteriorated connector can create problems. Switching large DC inductive currents is rough on the control relay contacts and that could be another source of problems. A dash mounted bypass switch would be a good back up for when things go wrong.
On the intake manifold dead center on the lower intake there's a fan switch/sensor in the water jacket that supply's the signal for the fan relay..The problem is the lower intake water jacket where the sender is located fills with sludge and insolates the sender from the actual water temp and the fan don't turn on till it's overheated and to late.
I found a few lower intakes with the sender hole complete plugged..
What I did was run a 30amp Relay to a Thermal Switch, out of a Renault K car in the Radiator. I had the Radiator shop put a threaded Bung in my lower tank.
The way that works is, I supply constant power to one side of the Switch (fused) and run the other side back to the Relay, then from the Realy I supply power to my fan. I also have an extra manual switch inside the car (hooked to the Relay) so when I'm at the track I can run the fan in the staging lanes to cool the Antifreeze that's in the radiator and I start the car evey so often to circulate the "Cooled" fluid into the motor.
my 2ยข
turbowagonman
What I did is buy an older VW thermal switch. Think Scirroco, Rabbit, etc. You can get them on Ebay in different temperatures. Search "temperature switch" or "thermal switch" or "VW temperature" Myself I like the higher temperature switches so the fan doesn't stay on as much. It should only be needed when you are caught in traffic, not while steady cruising. If you get a 160 or 185 it will be on all the time after the motor warms up. Go with a 192 or higher trigger point.
I machined a round fitting and tapped it to fit the thermal switch. I think it was 22mm x ?? I then drilled and grind a hole in the thermostat housing at an angle. (to reduce trapped air later)
I then had my fitting welded to the thermostat housing. Ohh ya, make the fitting the same material as your housing for welding.
Then I added a circuit breaker to the fenderwell that is attached directly to the battery. I get these at the truck stop. They are for trailer lights. Then from the circuit breaker to a heavy duty relay and then to the fan. I then wire a separate circuit through the thermal switch to activate the relay. This can also be from the circuit breaker if you don't mind that it can run without the key on. I like it that way to cool the engine compartment down after a hot shut-down.