My primary fan is working correctly. However, my auxillary fan never turns on. I took them apart today and jumpered the fan motors to a battery - both worked correctly. So now, I know the fan motors work, but I'm not sure what is causing the problem?

Is there a relay for the auxillary fan? Is there anything else I should check?

Any info would be greatly appreciated.

Thank you!

 

There is a relay for the fan. The relay is operated by a temperature switch in the RH cylinder head. Try grounding the lead at the switch and see if the fan operates. Your "problem" may be that the primary fan is cooling the system adequately, and the secondary fan is never turned on as a result.

 

My secondary only came on with the A/C on, I don't have A/C anymore so it hasn't come on since.
The switch in the head is set for over 240*'s, so if it doesn't get that hot, it won't turn on.

Like Vader said, your primary fan probably keeps the temp under control, like mine does. I haven't gotten past 180* yet this summer, and I've been in stop and go traffic for about an hour a couple of times with the outside temp a little past 90*.

 

After all the headache, it turned out to be a bad connection on the fan switch sensor. The keeper was moving freely and the wire was about 90% pulled out of the keeper/sensor.

So I cut the connector off and attached the new Hypertech one I bought. I then installed the new 200* fan switch... took it down the road... came back and both fans were running (my TPIS chip makes the primary also come on at 200*)!

Thanks again for the help!!!