I just installed dual tpi fans to replace my single fan. Now that the new fans are on they only kick on with the a/c, not with the switch anymore like the single fan did. Anyone have a clue what is wrong? Maybe the relay?

 

You should be able to discount the relay as a possibility. The ECM uses the very same fan relay to operate the fan when the A/C is turned on. If the ECM can turn on the fan in A/C mode, it can just as easily turn it on when the coolant temperature threshold is reached.

Are you certain the coolant is warm enough for the ECM to turn the fan on? Factory fan settings are typically around the 223°F point.

 

I have a 160 degree switch on and it won't kick on ever since I put the duals on. It worked fine with the single.

 

The fan switch that I have is for a tbi car. They do have a tpi fan switch. Is this the problem?

 

An OEM dual fan installation on a '92 should have had a relay for the primary fan operated by the ECM, and a second relay for the secondary fan operated by the ECM with a redundant path through an auxilliary switch. Hopefully, that's how you have it wired.

 

Umm.. I just cut the wiring harness for the single fan and ran each wire into 2 wires and then sent them to the fans.