My 1999 ES-300 has had an intermittent radiator fan stoppage for three years. Mechanics can't find the problem, because it's so intermittent. The symptoms are: temperature gauge starts to rise quickly, I stop, get out, open the hood and find the fan is not running. I tap on the relay box a couple of times and the fan starts. Then I am OK for anywhere from two weeks to six months.
The most expensive relay has been replaced, to no avail.
My question is this: Are the relays meant to start the fan only when it is required because of temperature? If so, is there a way to wire them so the fan runs all the time? Living in Arizona, I don't think the engine is going to get too cool.
Any other ideas or similar problems?
Thanks
Marty