My wierd rad fan situation (Page 2/2) D43DLU5 JUN 23, 08:49 AM Have an update that just leaves me scratching my head. I grounded the circuit and with the car on, engine off, the fan ran. I then proceeded to run the engine in idle until the temp gauge went well over the red, coolant overfill tank boiled over and the engine temp light came on. The fan never turned on once. I took temps with a laser thermometer and the radiator and thermostat housing reached about 250° F. The next day, I drove the car to fill it up with gas. When I parked it, the fan was running without the A/C on. Nothing had changed other than the fact I drove it. The temp never exceeded 220° on the gauge. Any ideas why? fierosound JUN 23, 09:25 AM quote Originally posted by D43DLU5: Have an update that just leaves me scratching my head. I grounded the circuit and with the car on, engine off, the fan ran. I then proceeded to run the engine in idle until the temp gauge went well over the red, coolant overfill tank boiled over and the engine temp light came on. The fan never turned on once. I took temps with a laser thermometer and the radiator and thermostat housing reached about 250° F. Fan switch must be bad. Get a 210F/200F http://rodneydickman.com/pr...o.php?products_id=88 theogre JUN 23, 12:00 PM Plug for the switch can be bad... More so since Already tried replacing the switch. Carefully use a needle to pierce the wire above the plug and ground the needle to make sure fan runs then jump the needle to the switch. New plugs should be available as a "pigtail" part from Dorman or others. If have Ω meter, place on switch "pin" to engine and should = 0 when on. Again, The low speed already turn on ~ 220°F if someone didn't remove it. Should have a red plug w/ 2 wires. Fan running and engine "cool" means little. Rad, pipes, etc can still be very blocked, iffy T-stat, iffy heat loop, and fan running only hinds that. Must need Rad Fan on w/ car moving is often problem Not a solution. Even in Hot weather l4 doesn't need fan running all the time. Car over heats fast is same thing... l4 should take time to heat 3+ gallons of "water" at idle. See my Cave, Thermostat, Crushed Pipe and rest of section.