Help me trouble shoot my electric cooling fan wiring. . .
So I converted to an electric cooling fan and aluminum radiator from a mid-90's Volvo because our '94 YJ Wrangler's radiator leaked, the passenger side mount was broken, the heater core had a leak, and we were having over-heating issues during the summer and in heavy traffic.
Now that I have it done, the fan doesn't come on in low-speed when the temperature reaches the set-point of the temperature sensor. . .the fan comes on in high-speed when I flip the manual over-ride switch (I only have one temperature sensor so I want to use that to control the low speed and have the high-speed option if I need it).
I read most of the electric fan conversion threads on here before I started, but I'm still figuring electrical stuff out. I'm using the Volvo controller to control the fans. . .here's how I wired this thing up. I ran battery power to the fan from the battery, through a 60A fuse (factory fuse for the fan in the Volvo), through an 80A relay to the fan. The 80A relay gets activated by an in-dash switch that gets power from a switched source at the fuse panel. . .this is always on except in the case of a water-crossing. The fan is grounded to the body (the ground is good).
I have a 30A Bosch relay with 87 and 87A pins to route power to the appropriate fan motor switch (low-speed or high-speed). I have the high-speed trigger connected to 87A (normally open); the low-speed trigger is connected to 87 (normally closed). Pin 86 is connected to an in-dash on-off-on switch (powered from a separate switched power source from the fuse panel) and pin 85 is grounded to the body (same ground point as the fan motor itself). Finally pin 30 is connected to the in-block temperature sensor.
My only guess is that I misunderstand how the temperature sensor works. I thought that it would send a voltage to pin 30 when it closes at 185*F so that is when the low-speed fan should come on. . .since the temperature sensor only has one pin I'm guessing that this should be used as a normally open ground that closes at 185*F and that it doesn't actually send a voltage to the relay, but only completes the circuit when it closes. Is this correct? If so, does that mean I need to connect the temperature sensor to pin 85 (ground) on the relay and run a switched power source to pin 30. . .that way power is always available to the relay, but doesn't actually flow until the temperature sensor closes.
The only reason the above wouldn't make sense to me is if that were the case then the high-speed fan shouldn't turn on either. . .I mean for the high speed fan to come on power has to be coming into the relay. . .so why doesn't my low-speed fan come on. I know the low-speed is good (I tested it before I pulled it at the junkyard and if I switch the trigger relays the fan will turn on in low-speed when I flip the manual over-ride switch).
I used the Volvo relay to run my fan and I ran the hot through a 40 amp fuse into the Volvo relay and used an inline temp switch to trigger it. IIRC, the only things that needed to be hooked up were the hot and the ground from the switch as everything is pretty much plug and play. I have not run a water crossing cutoff for this but I understand the only thing I would have to do is put a relay in the hot (12v) between the power source and volvo relay and wire it to a switch in the dash....
Not the sharpest bulb in the box....
My Jeep is possessed with the goal of making me lose my religion....
To, sorry I didn't notice you had posted the switch in the schematic. . .I searched it online, but I couldn't find what the thread size on it was. . .is it the same thread as in the side of the block on the driver's side just inboard of the exhaust manifold.
It's OK I added the part number after you asked. It will not work iin your block. It's M22 x 1.75 and is used in the upper radiator hose along with an adapter or juckyard part out of a Saab? I think. I'm making an adapter out of 1.5 x .095 steel tubing and a spindle nut by Dorman for a Mazda 3.