View Full Version : Hopefully my final wiring question
Tocoti
02-22-2014, 06:33 PM
MK4 wiring harness supplied with complete kit. The fan switch is normally closed. It closes the fan relay and turns the fan on when cold. I read the instructions in the manual, but if the relay is energized with the switch grounded then the fan is on. I have it on a switch in the dash harness for now only because I want to do a first start tomorrow.
Not following you totally. What's the question?
Tocoti
02-22-2014, 09:16 PM
The fan is on when cold because the fan relay is grounded at the switch.
Tocoti
02-22-2014, 09:27 PM
It has 12 volts to the fan relay. All it needs is ground to activate it. That is the thermoswitch on the motor. It is normally closed. I think it should be normally open so not to make the relay close and send power to the radiator fan. Right now the fan will run when it is cold. Do I have a bad thermo switch?
DaleG
02-22-2014, 10:51 PM
I suppose you have the Ron Francis harness since you have the complete kit. Page 18 of the Chassis Harness manual shows the switch wiring. I'm thinking that the switch is wired wrong? The switch wires should be orange cooling fan wire to one post, and the two brown wires (fan switch feed and gauge feed) to the other post. Or am I missing something? What is your thermo-switch reading; coolant or between the radiator fins?
Just caught on; when you say switch, you mean the thermo, not the toggle? Sorry.
CJBergquist
02-23-2014, 12:28 AM
My RF harness does not support a thermostat (cold open, hot grounded) switch. It supports a dash mounted SPST toggle switch. Hot (brown feed) on one lug and the orange (radiator fan) on the other lug of the switch. Turn on the switch and it closes the "radiator" relay turning on the fan. I don't think you can use a thermostat switch and the RF fan relay that's because one side of the primary side of the relay is grounded in the fuse/relay panel the other side is the orange wire that needs to be wired to the on/off switch that provides 12volts to the primary circuit actuating the relay. Grounding the orange wire isn't going to do anything.
You said the thermostat switch is bad...check with an ohm meter...one lead on the top connection and the other grounded to the block. It should be "open" when cold and "closed" when hot.
I also have a thermostat switch but I had to add a second relay to make it work. I can turn the fan on manually or let it get hot enough for the thermostat turn on/off the fan.
Hope this helps.
Tocoti
02-23-2014, 08:53 AM
Yes it does. Thank you. I'm just going to run it on the toggle today and wire the thermo switch later. The thermo switch reads closed when cold.
CJBergquist
02-23-2014, 08:46 PM
Super. Good luck with the first start...get someone to video the event and share with us.
Tocoti
02-24-2014, 07:05 PM
Super. Good luck with the first start...get someone to video the event and share with us.
I posted the first start under the roadster title. I got some bad gas so it took a bit to get the old crap out of it. I actually drained the carb, lines, pump. Went and got fresh gas. I used a small gas tank and not the cars fuel tank so I didn't have to flush that out.