Cadillac Repair: 1987 Sedan Deville temperature warning light, engine oil dipstick, controller unit

Question
Hi
I have a 1987 Sedan de Ville with the 4.1 engine with a strange problem.

Back in Jan.07, the radiator started leaking. I had it replaced by the guys at the local service station. All was fine until the Coolant fan temperature light would come on for awhile then shut off. When the light came on, I figured the cooling fans weren't working. I raised the hood and both
fans were running.The hot light never came on.

I took the car back to the Yahoos that installed the radiator and was told that this is normal!? They said the light comes on to tell you that the cooling fans are on!

Are the fans running too slow or do they only run at one speed? What triggers the cooling fans into operation? The CTS?
Trying to figure out how to troubleshoot this beast.

Thanks,
Ed

Answer
This is NOT true: "They said the light comes on to tell you that the cooling fans are on!"

If your referring to the RED light on the dash possible fault is either:

1. The engine metal temperature switch which has a single green wire attached to it and is located about 6 inches down beside the engine oil dipstick in the cylinder head.

2. They put in a USED or rebuilt radiator.

3. Check to make sure that the radiator is FULL of coolant and also that the plastic overflow jug for the radiator is at the full mark.

Check above step # 3 and then replace the engine metal temp switch as indicated in step # 1.

The coolant fans are controlled bt the CTS thru afan speed controller unit.