Boham92RS

I just completed my 350 swap. (LO5 w/ Lt1 cam, TBI). The engine is running great with the exception of my cooling fan. I had installed a lower temp fan switch when I had the 305 (200 on 185 off?), which I transferred to the 350. Now, the cooling fan will not come on until the engine runs dangerously close to overheating. I have checked the wiring to the fan switch, and it looks good, however I am unsure on how to test it. I am relatively sure that the fan itself and relays are good, if I put the AC on, the fan will come on and the car will cool down without a problem. I have been using this as a temporary fix, but I would like to get the fan working properly again. I have scanned the car, and the computer is seeing the correct temperature, so I believe the new CTS is good.
Any ideas?? New fan switch? It always worked fine in the 305, so I cant see why it would coincidentally die now. Is there a way to test the wiring to the switch? Thanks!

Vader

Boham,

If this is an auxilliary fan switch, it should ground the dark green wire in the fan relay circuit. You should be able to test the switch with a DMM on a resistance scale. The switch should be open (no continuity) until it reaches the set temperature, then close (zero ohms) until the coolant drops below the cut-off temperature. If the switch itself is operating correctly, there is likela a problem with the added wiring. You can test the wiring by grounding the dark green wire, at which point th efan should turn on.

Boham92RS

Vader, thanks for the reply...

This is the only fan switch the car has, to my knowledge. It is an RS, and as such, only has one fan. The switch i am referring to is in the passenger side head. I am trying to remember what color the wire was, and it could very well have been green. I will try to ground out the wire going to the fan switch to see if the fan comes on. Since the switch needs to ground out the circuit, should it have a direct connection to the head? When I installed the switch, i put thread sealer on the threads as it is in contact with coolant.. Should I not have?

burntblues

I don't think that putting thread sealer would make a difference. You'd still get a contact patch where it'll ground out. One thing that you might want to do is check to make sure that it isn't the fact that your gauge is off. When I swapped motors I had what appeared to be a huge overheating problem. After months of trying to track it, it turned out that the switch was wrong. The temp would creep, on the gauge, to way past 220 and almost to 280, then it would come down. I put a digital thermometer on the intake manifold and found that it was only getting as hot as 195. It totally screwed with me though...

-=-Mike

The sensors are really touchy and if they get bumped they'll mess up or break...

Boham92RS

hmm.. ok, well it may very we be the switch then. I may as well just go for a derale adjustable switch instead of fooling around with the non adjustable crap. Plus, its a huge pita to change the fan switch in the head. Well, not that bad, but drain the coolant, etc.. Anyone have any experience with the derale switch? 16759?