Unlike my earlier-year 240's there is not a switch in the rad on the pass side. What makes this fan come on?
Fan runs fine with 12V applied from external source.

That fan isn't meant to cool the engine. It's strictly meant to cool the A/C's coil in front of the radiator, and is controlled solely by a pressostat (pressure controlled switch) in the A/C lines.

If you are a VCOA member and therefore have back issues of Rolling (the club's magazine), you can find my article on how to change this so that the fan goes on both when the A/C needs it and also when the cooling system needs it:
Volume 25, issue #4 (July/August 2007), page 25.

Actually (unlike 700/900 cars with such a switch as you describe), I'm certain that no 240s ever came OEM with that switch. Since you've had such a car, you should know that it had to be an aftermarket radiator (e.g., Nissen's 3-row, one that's 50% larger than the OEM, 2-row radiator) -- it's a common upgrade (I put them in all my cars, just in case).

And to the modification I describe in the article, you would need that Nissen's radiator anyway in order to have that switch.

Regards.

In a 92, the e-fan only runs when the AC is turned on and appropriate refrigerant pressures are reached, it is strictly meant as a aux fan for when the AC needs it. If it never turns on and your AC works, you might have a bad aux fan relay, it is black and mounted on/near the ignition coil.

Hope that helps!

jorrell
--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

So you are saying that whenever the AC is on(and mine works good), the Electric fan behind the grill should be on. It is not a function of how hot the coolant gets?
So I should see voltage to the coil of the relay whenever the AC is on. And as a result, I should see voltage to the fan.

Where is the switch to supply voltage to the coil of the relay?

I have not dug through the schematics, but from assumptions (I COULD BE WRONG), it appears that the fan relay is "triggered" by the AC being on and the pressure switch in the AC line on the passenger side frame rail near the radiator being closed. With the AC turned on, unplug the connector from that pressure sensor and jumper it or short the line to ground, does the fan come on? If not, suspect the relay. Okay, the pressure switch could be bad as well.

According to the Bentley manual, 105, 107, or 109 is your problem.

jorrell
--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

It was the relay. Relay is clipped to side of coil. I tested relay by hooking up to 12V(cordless power tool battery works great for this). Relay clicked,, but no continuity of contacts.
If I jumpered two red wires in the plug, the fan ran. So I opened up the relay and found the bad solder joints, which I resoldered.
Resealed the relay with silicon caulk, put it all back together, and the fan comes on once a certain amount of pressure is built up in the AC system.
Now let's see what happens when idling on a hot day.

Thanks to all, as usual.