UkurS4

Bit of an issue on a 1986 200, any BTDT's

The fan runs on it's highest setting constantly, with just the ignition on and when the engine is running.

RussB

This relay is located in the auxiliary relay panel, behind the left side dash. It's a 70 Amp relay with two large (maybe 3/8 inch wide) spade terminals for its contacts. It requires a large force to remove from and insert into its socket.

Another possibility, but less likely, is that the radiator fan thermoswitch contacts for fan speed 3 have welded shut.

SteveJ_in_TX

Since the 3rd speed relay is such a pain to get to, do the easy stuff first and pull the connector to the radiator fan thermoswitch. Switch on the ignition and see if the 3rd stage fan comes on. If it does, the contacts are welded on the relay. If it doesn't then the rad thermoswitch is bad.

Good luck, and let us know what you find.

UkurS4

I went out to the garage this morning and???
Yep it is now an intermittent problem, she won't do it now.
I will keep my eye on it over the next couple of days.

UkurS4

Went out for a drive in the old girl, stopped and then came back to her, turned on the ignition and the fan started, opened the bonnet pulled the connector on the thermoswitch and then turned the ignition back on.
Fan still spun.

Guess it is the relay then!!!