Hi
I'm new to the forum. I have a 1993 40th addition vet. The electric fans never come on. The secondary fan comes on only when the AC is running. The analog temp gage gets to the notch before 260 and the ditg temp gage reads 5 to 6 degrees higher. Is this normal? I drive the car around without the fans coming on and the car stays cool. But if I idle the temp does go up. Is the car just not getting warm enough for the fans to kick in? Any suggestions?

 

I found that the secondary fan fuse was blown so I replaced it and let the car warm up to 227 and none of the fans kicked on. I turned on the AC and both fans came on then I turned off the AC and turned it on again and the only fan that came on was the primary fan and the secondary fan fuse blew again. The primary fan still does not kick on by itself only on with the AC running. Could it be a relay, temp censer or a bad fan?

 

It may be wiring. That is probably why the fuse is blowing. You can try a visual inspections but it's best to check with a multimeter.

 

check the wiring to the fan switch..

 

Perhaps a previous owner added some wiring or a switch to try and turn-on the fan(s) on manually.

Following applies to LT1's 1992-1994 (95-96 runs both fans on slow/high speed based on similar 'trigger' events):

===== with the A/C OFF =========

at about 228 degrees F (digital dash reading), the PCM grounds the 'primary' relay (driver side fan, relays are on driver side of radiator housing) which directs 12vDC to the 'primary' fan via the relay.

If the temperature drops to 218 Degrees F, the PCM un-grounds the 'primary' relay to turn-off the driver side fan.

By contrast, If the temperature continues to climb, then at about 239 Degrees F, the PCM grounds the 'secondary' Relay (passenger side fan) to direct 12vDC to the 'secondary' fan. The 'primary' fan should continue to run.

Then, if the temperature drops to 228 Degrees F, the PCM will un-ground the 'secondary' relay to turn off the passenger side fan.

=== with the A/C ON =========

The PCM adds one additional 'input' to its decision of if/when to turn on the 'Primary' fan.

THe PCM determines the AC system pressure via the AC pressure switch (switch mounted in the high-pressure AC line near the firewall).

When the PCM detects a normal increase in pressure (indicative of normal warm air temperatures), it then turns on the 'primary' fan, regardless of the coolant temperature.

Further, once the PCM detects a further increase in pressure (perhaps indicative of hot ambient temperatures), it then turns on the 'secondary' fan, again, regardless of coolant temperature.

Here's a link of a write-up I recently did on this subject:
http://forums.corvetteforum.com/show....php?t=2046808