Thread: D2 Td5 electric fan always on

As already mentioned, the fan will be turned on by the ECM when stationary for a few different reasons.

1. If the AC is on and ambient temperature is over 28.

2. If engine coolant temperature is over 110°c.

3. If a bad overheat has occured and the fault not cleared (I can't remember the number, but it's hot, you would need a new head after).

And

4. Yes, I think a failed temp sensor might put it on as well.

I'd be checking the relay as suggested, then go from there.

The ATC ECU could also be faulty I guess.

I was going to post about the stuck relay, but then OP said he can control fan via Hawkeye.

I would try two things.

1. disconnect the coolant sensor plug

You say you have another D2? If so,
2. try the HVAC head unit from that other D2. Not hard to remove, just the tricky side lugs (credit card sized things help) couple of plugs.

Also, I can't recall where/how ... but there is a diagnostic process you can go through on the HVAC head unit. Press a few buttons in a magical way and so forth.

Strange thing, I remember I had this always on condenser fan on my D2a. I didn't diagnose it, thought it weird, and annoying as back then the battery was very weak, and I got caught a couple of times trying to start it with weak batt ... and problems that come with that. I just went away itself. I can't remember doing anything specific about it, and the only thing that may have come close to an accidental fix, was that one day I was sorting a leaking cooling system. Had to sand down the temp sender port as part of that fix up and I removed the temp sender connector to be sure no breakages there. I don't specifically recall that it stopped self running after that, may have before that too.
But it was annoying that when having ign on whilst I was sorting the D2a, having that fan on ... had to keep it on a charger too.