I lost both my cooling fans on my 87 tpi car this weekend. We were autocrossing the car and after my 3rd run the car boiled over. I turned the ignition on and no fans at all. So I brought the car home on the trailer and couldn't get the fans to come on no matter how hot the car got, or by grounding out the temp switch wire going to the right head. Just a few weeks ago I had replaced the fan switch in the right cylinder head because the old one was bad and the right (passenger) fan ran all the time. I used a napa #TS6717 switch that turns on at 200 and off at 190. For several weeks everything worked perfectly, but quit on saturday.

I verified that the fans were both good by supplying power to them. Since I had a race on sunday also, I rewired both my fans with two 30 amp relays from radio shack. I set it up to have the power to the relays come directly off the battery (fused) and used a wire on the stock fan harness that was hot with the ignition on to switch on the relays, then ran power wires to both fans to turn them on. On both relays I DID NOT ground them, I used the temp switch in the right cylinder head to supply the ground to the relays when the engine got hot.

This seemed to work pretty well. But my question is, does the temp switch in the cylinder head I'm using to supply the ground to both relays have enough amperage capacity to supply the ground to both fans and not burn itself out? The switch is originally meant to run one fan, not two.

Also, does how I've wired the fans make any sense? I know it works, but is there a better way to do this? If my design is acceptable, I'm going to take the harness I made apart and do it right this time. I had very little time to put this togehter, and it ain't pretty, but I will make it look better now that I have the time to do it right. But before I do this I wanted to make sure my design is a good one before going to the trouble to make up a proper wiring harness.

(P.S. I read the fan articles before posting and they didn't give me my answer on the current capacity of the temp switch I'm using to supply the ground to the fans)