1990 Corvette cooling fans question
Thread Starter
Intermediate
Joined: May 2013
Posts: 25
Likes: 1
From: Nebraska
1990 Corvette cooling fans question
Hello everyone. I'm a new owner of a 1990 base Zf6. 140k miles. Other than rear exhaust it is stock. It was in need of TIC when purchased in November. I have got it sorted out for the most part, but I'm still having an issue with the electric fans. The primary (driver's) fan will turn on around 230 degrees but I can't seem to get the secondary fan (passenger side) to turn on even when running the a/c. Both will turn on via the ALDL ecm code retrieval.
Any ideas? Anyone know how the fans are supposed to operate? I already checked the relays and fuse.
Thanks in advance
JD
Any ideas? Anyone know how the fans are supposed to operate? I already checked the relays and fuse.
Thanks in advance
JD
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Don't have my FSM handy but if memory serves a particular set of circumstances must be present for the 2nd fan to operate. Something like 245+* water temp &/or excessive temperature or pressure in the AC high side line.
A jumper wire across the 2 fan relay ground wires will run both fans whenever the AC is operational or when water temp reaches 228*. With the relay mod & the AC on the water temp should stay @ thermostat opening temp.
A jumper wire across the 2 fan relay ground wires will run both fans whenever the AC is operational or when water temp reaches 228*. With the relay mod & the AC on the water temp should stay @ thermostat opening temp.
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
BE CAREFUL! If you run it too hot you'll end up like me - replacing the engine when the rings go away.
I got a "fan switch" for mine - both fans come one now around 185 and it stays nice and cool - after replacing the clogged radiator that is.
I got a "fan switch" for mine - both fans come one now around 185 and it stays nice and cool - after replacing the clogged radiator that is.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
There are various signals to the ECM that tell it the A/c is operating
If the ECM is not getting the correct signal to show the A/c is operating then it will not activate the 2nd (A/c ) fan
There is a A/c request output from the A/c programmer to the ECM
There is a A/c on input from the compressor side to the ECM
Possibly also check the the A/c pressure switch(s)
and you are lacking a signal to operate the fan
Last edited by vetteoz; May 11, 2013 at 02:15 AM.
