Just recently bought a 89 Iroc with 5.7L engine dual fans. They seemed to work correctly. Now as soon as I turn the key to "On" the primary fan comes on with the car stone cold, then when I start the car an run it for a few secs the secondary fan runs. I read somewhere on this board it could be the A/C press. switch (the A/C, doesn't work, compressor only cycles for 1 sec) Can anyone help.

 

the drivers side (primary) uses the coolant temp sensor in front of the block/intake manifold, i would suspect that to be a potential problem. maybe take a look at that, it seems that maybe its gronding out the relay right when the relay gets power.

 

I am not sure which is the primary fan and or secondary fan, I checked and the passenger side is the first fan that runs when the key is "ON" then when the car is started the secondary (driver side fan) starts to run. Could it be the A/C pressure switch? (Where is the pressure switch) I tried swapping the relays to check them and they (relays) seem fine.