Hi,
My passenger cooling fan won't come on. I noticed my car was over 250 today so I popped the hood and the driver fan was on, but not the passenger. I turned on the AC and it still didn't come on. Could this be the relay or temp switch on the head?
thanks
Craig

 

It could very well be either one. I'll guess the fan switch in the head, since that's what's bad on my car right now

 

don't rule a bad fan motor if the above listed are good.

 

Dont go any buy anything quite yet. Switch the plug connectors on the fans and see if the passenger one even turns on. The motor may have went south. This info was taken directly from the technical articles section in this site:

According to the 1990 service manual, the primary fan is controlled by the ECM and will come on when the coolant temperature reaches 190 degrees F. The secondary fan has its own temperature sensor in the bottom of the engine block (passenger side) and will turn on when both of these conditions exist:

The coolant temperature is greater than 222 degrees F
When the A/C control head pressure is greater than 1600kPa and the vehicle speed is less than 40 mph

Im ditching the dual fan setup on mine and switching over to a single large fan. One big fan will cool better then 2 small fans. Besides, half the time both of them are not even running at the same time. Just like in your case.

 

It is easy to check the fan switch. Pull the wire from the switch in the passenger side head and ground it. If the fan comes on, you know the motor and relay are good, so it must be the switch. I don't recall if you have to have the key in the on position or not though.