Jason_The_Angry

Good Evening,

Weird electrical gremlins after the car spend a few weeks in the cold. I swear it's mad at me.

1.6L, turbocharged
DIYPNP Megasquirt - cooling fan control enabled
AC has been removed, but the AC fan is still installed, and the refrigerant sensor circuit has been jumpered to allow control of the AC fan by turning on the climate control blower with the AC switch engaged. I don't use it all the time, but in summer traffic, it helps with temps.

Car has been behaving well. I left it outside the garage for a few weeks while doing some small house renovations (it's winter here). I mean to go for a drive this morning (50F ambient), and I notice that both the cooling fans come on when I turn the ignition to "Accessory" to let the fuel pump prime.

Car starts. Car runs. Everything seems normal, but the fans stay on. I turn the car off, fans turn off.
I pull the fan relay under the hood in the passenger side fuse box, cooling fan turns off.
I pull the AC fan fuse in the passenger side fuse box, AC fan turns off.
I check the cooling fan relay on the bench. The solenoid clicks when you apply voltage, so I think it's fine, but I didn't get to run a multimeter on it tonight.
I checked the Megasquirt settings for ALED, they were set to turn the fans on at 185F CTS and a min RPM of 500. CTS seems to be reading normally.
I pulled the refrigerant switch jumper, both fans still stay on.

It almost seems like the relay that would turn both fans on when the AC is activated is stuck. I "think" the AC fan relay is on the passenger side front, kind of part of the wiring harness? Do you think that's my best place to check next? I was starting to lose my mind this afternoon, so I figured I'd take a break and see if anyone else had any thoughts.

Thanks in advance for any insight you can give, I appreciate it.