At what temp should the cooling fan come on?
 

Today on a very hot day with AC running I got stuck in traffic and my coolant temp climbed up to about 105C, but I didn't hear the main cooling fan (actually I've never heard it). At what temp should it stop free-wheeling and start spinning fast? My aux fan is working, but I don't know about the main fan.

I think 110c or 115c.

I don't think that's too high a temperature to worry about. But anyway, you could test if your viscous fan clutch locks up when it should by shutting off the engine when it's hot and watching the fan as the engine shuts off. The fan should come to a stop right away.

Holson, yes my fan comes to a stop right away. I thought the main fan should spool up at 100C or so and that's why I was a little worried. But if it's really set to come on at 110 or 115 then most people including myself should never get to hear it. Is there anything else I can do to check the fan operation?

It sounds like you are talking about the auxilliary fan, the electric one.

It does not come on based on engine temperature. It is simply there to bring down excessive high side a/c pressure. There is a pressure switch in the r/d that turns it on to bring down high side pressure, thus protecting the a/c system.

Have a great day,

Larry, thanks for the info. However, I was primarily concerned about the main cooling fan, not the aux fan.