So I bought a 2000 Grand Marquis, 200k miles on it, and have problems with it straightaway. To the point - I have an issue with the cooling fan. It works only when I turn on the AC. During normal drive without the AC on, the cooling fan does not turn on and car slowly overheats. As far as I know, the cooling fan works on a two different speeds (high and low) and it looks like my fan works fine on the higher speed (when I trigger it using the AC), but not on the lower one (to constantly cool the engine).
Things I'm almost sure about: - temp sensors work fine - the radiator fan motor works (because the high speed fan during the AC works) - there is a voltage going on so the PCM (or however you call the computer) gives a signal to turn on the fan
Moreover, after a short diagnosis I found out that the green little resistor mounted on the radiator fan plastic casing looks to be blown out, so I order a new one. It didn't help. I'm literally losing my mind.
Well realize that's all the computer run system and rather than mess with that I personally just tell people put on a toggle switch to run the fan. You can turn on when you want and when you get on the highway and don't need it, you can turn it off
