I bought a hypertech fan switch and it's not working for me. When I put it in the block, the temp gauge doesn't work and if I put the stock one back in the temp gauge and fan works again. Is there something that I could be doing wrong? Is there two seperate sensors? One for the fan and one for the gauge?? I put it on the drivers side by the headers. I also have the 69-80 350 block if that makes a difference.
thanks for the help!

 

well maybe the one you got is compatiable for the block you have. who knows. mine went in the passanger side head. and i never had problems with it. i would return it and just try the manual wiring way. who knows

 

I have the Jet Fan Switch . Works great .

 

AFAIK, the t4emp gage is the one between #1 & #3 plugs and the fan switch is between #6 & #8.

 

If you have 2 fans, the driver side one is controlled by the ECM from the sensor in the front of the intake and the second one is controlled by the sensor in the pass side head as well as the sensor on the A/C line.

The Hypertech is supposed to go in the pass side head.

The sensor in the drivers side head is supposedly only for the temp gauge in the cluster.

My fans on my Formula disn't come on automatically when I bought the car and was too lazy to fix it right, so I just wired up 2 switches to the 2 fan relays so I can turn either fan on and off when I want.
Right now I just leave the drivers side fan on all the time and the temp stays at 170 all the time.

 

well I only had one hooked up on the drivers side originally and the fan and temp still worked. Why would the fan still come on??
thanks

 

ECM controls the primary fan (if you have 2 fans)

 

My whole a/c system is removed, would this effect the switch?
thanks

 

It shouldn't. do you have one or 2 fans?

 

I have two fans, the switch on the passenger side head has a wire by it just dangling there, tommorow I will try and hook it up to it and see if it solves the problem. Which fan does the fan switch turn on, the drivers or passengers side?
thanks for the help!

 

It controls the pass side fan. It loweres the turn on from 220 to 160 or whatever the instructions say.
The Drivers side fan can be programmed to come on earlier in the prom or you can buy a Hypertech Thermosater chip and a 160* thermostat and run that.