Thread: How can I tell if my electric fan is drawing too much current.

Tweet

Here is a neat site that explains relays if you are not familiar with all the terms.

http://www.bcae1.com/relays.htm

You could control the dual speed fan using one temp sensor and one relay (your current setup) plus a toggle switch (Single Pole, double throw). You would connect the output of the realy to the input to the toggle switch. Then, you would hook the normally closed toggle switch output to the low speed fan motor. The normally open circuit would connect to the high speed fan circuit. You would have to remember to turn the switch back to the low position.