michael0156

1987 5000S 2.2L Auto Trans A/C

My cooling fan wouldn't come on during normal operation. My heater blower also is not operating, but I don't believe it's related to my radiator cooling fan problem. Trying to solve the cooling fan problem I replaced the thermoswitch mounted on the radiator.

Before I replaced the thermoswitch the cooling fan would not come on at all. After replacing it I have a different problem. The fan still won't come on when the engine is running, but when I turn the ignition off and the radiator is hot, the cooling fan comes on at low speed. When I turn the ignition on, without starting it, the fan turns off and stays off after I start it.

I removed the connector from the thermoswitch and shorted the connector's 1st and 3rd terminals and the 1st and 2nd terminals with the ignition off. The fan did not switch on. I turned the ignition on (without starting) and I had low speed from the 1st and 2nd terminals of the connector that goes to the thermoswitch when I shorted them and a higher speed when I shorted the 1st and 3rd terminals. Neither of these speeds were as fast as what I get when I short the load carrying contacts of the fan relay in the fuse panel. I can only find one fan relay and my Haynes manual doesn't help very much.

I checked the new thermoswitch (bought from Auto Zone) by placing it in boiling water and ensured that I had a short between 1 and 2 , but I did not check that the high temp terminals were shorted when heated higher. I also did not check the orientation of the thermoswitch short relative to what connector terminal shorts made the fan run.

The only thing I can think of at this point is that the switch was manufactured backwards, or the plastic piece with the keyway was put on 180 degrees out when it was attached to the thermoswitch brass. That would not really explain what is happening now, but I can't think of anything else.

HELP! Anyone have any ideas? Where can I get a good schematic and wiring diagram for this car?

Mike
michael0156@earthlink.net

rooster 2

buying sensors from them. Twice I bought sensors, that just would not perform correctly, so be suspicous of Auto Zone sensors.

86_5K

Either the thermostat is not openning up or your radiator is cloged up. In both cases,the thermoswitch at the bottom of the radiator wouldn't be able to see any sign of high temperature because the hot coolant couldn't get there. But the sensor controls the after-run radiator fan is on the engine head. It feels the heat and turns on the fan after you shut off the engine. To test whether this is the case, feel the temperature difference of the upper and lower coolant hoses between the engine and the radiator. If the lower hose is always cold, then that is the problem.

The testings you mentioned tell me that you have a working system otherwise.

By the way, if you want to test whether the sensor is working for both 2nd and 3rd stage, put it into salt water or coolant. As you know, plain water won't reach the temperature for the 3rd stage.

Zhaoming

michael0156

Zhaoming,

Thanks for the tips. I think water is flowing fine because it doesn't overheat when I bypass the fan control relay and cause the fan to run all of the time.

I'm going to check the thermostat tomorrow and be sure. I'll let you know how that works out.

Thanks again for your help,
Mike