1991 Subaru Legacy Radiator fans don't turn on when heater

1991 SUBARU LEGACY
170,000 MILES • 4 CYL • AWD • MANUAL
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I have an unusual problem. If I have any of the environmental controls on, AC, heater, vent, bilevel, defrost, etc., the radiator fans do not come on even when the engine is extremely hot. As soon as I turn the environmental controls to off the fans come on immediately and seem to go on and off as would be expected.

Another aspect of this is that when I turn on any of the environmental controls, the AC compressor engages.

Any ideas would be appreciated.
Apr 17, 2009 at 5:59 PM
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ABD141
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My car is a year older and had a similar problem, except it didn't kick on when the AC came on. It is possible the problem lies in the area of the thermostat/waterpump

If so, thermostat is an easy fix. Waterpump...not so easy.
Apr 19, 2009 at 4:35 PM
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I thought possibly the thermostat as well so I changed it from a parts car I have and no difference. Also, since the fans operate normally when the environmental controls are off it shouldn't be the thermostat.

I have also changed out all the relays in the under hood fuse box for the AC, but no help. I am starting to wonder if it could be the mode actuator for the environmental controls as it interrelates to the AC and the cooling fans according to the wiring schematic.
Apr 22, 2009 at 8:55 AM
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