V8 cooling issues

[FBFISH@aol.com]

Folks- Lately I've noticed the engine temp has been running somewhat hotter
than usual. Normally it runs around 75 deg C. It is now running around 85 deg
C. The viscous coupled ( mechanical) fan runs ok, but the electric fan only
runs when the AC is on. I have checked the engine coolant sensor resistance
and it is within spec. Obviously the fuse is ok (also checked), and the
resistor board looks good. With the data I have, it looks like there are three
relays controling the fan operation. Low speed, 2nd stage, and third stage.
Turning on the AC energizes one of these relays, but that is the only way the
fan will run. Since the fan won't run in any of the three modes, I have ruled
out the relays. Unfortunately my doc. doesn't show any common problem areas,
so I have either erred or am stuck. Any BTDT help at hand??
Frank Santoro
1990 V8
Kingsville Md