Cooling Fan(s) Mystery

[bstandley1]

After spending the better part of the day rewiring my cooling fans, I think my overheating problem is finally resolved. I have the the standard twin fan pushers plus a thin line Spal puller I added last year. The car has always heated up in traffic and continued to do so even after I installed the puller. Now that I have a new engine, I was determined to figure out what the problem was. After running power directly from the solenoid to each set of fans, I was astounded by how much faster the fans ran. The existing set up used power coming off the hot side of the ignition switch ... I re-used the same relays I installed last year and the same toggle switches and now the fans operate thet way they'e supposed to! I took a test ride in traffic and the temperature never went above 185. I don't quite understand why the hotside of the ignition was the source of the problem but I'm sure relieved that I can drive in traffic without overheating. Life is good ....

Bob

[Naumoff]

Bob,
That is very interesting.

[Slither]

The first thought that comes to mind is a wire sizing issue, though I do not have the experience on the ground with the wiring harness... yet (hopefully someday). (It sounds from your post that this bypasses the ignition switch itself, rather than going through it.)

If the wire sourcing the supply current is too small, it can act as a resistor in the circuit causing a reduction in source voltage at the load... the old don't use too small of an extension cord or you'll burn up your saw problem. In this case you actually get a voltage drop across the wire end to end :eek: (a teenie-weenie drop is normal since the world is not perfect;)). This larger than normal voltage drop could cause the fans to run slower than designed:( and they could also overheat:(. Ratty connections can cause the same type of problems due to increased contact resistance.

Maybe Jim Harding or some of the veterans can speak to wether this could be the problem or not...