Hey ht, my girlfriend drives a 99 RL and has just told me for the last year when she is stopped and idling her coolant temp almost maxes out. So I went to take a look and neither coolant fan is turning on. After letting it cool down and starting it a few times both fans kicked on randomly. Now they won't come on again. Any ideas? Possibly a bad relay?

 

Jumped the switch on top of the thermostat and fans didn't come on. Fuse in the cabin is good. Fans come on when ac is activated.

 

In the unplugged fan switch connector, measure voltage on the power wire and continuity to body ground on the ground wire. What do you find?

Also post the circuit diagram for the fans.

 

Thanks RJ! I have continuity to ground thru the one and 5 volts supplied thru the hot wire

 

I measured the voltage when we had the jumper in and as soon as the jumper touches the ground wire the voltage drops to 0

 

This^ is the problem - it should have battery voltage. Check voltage of the same wire on both sides of the relay.

 

It says I have 14v on one side of the relay and 0 at the other three. This was at the Rad fan relay. At the rad fan main relay I have 14v on two of the pins and 0 at the rest

 

Found someone with a similar issue so im going to try to trace the wire with these diagrams. http://www.justanswer.com/acura/1wfuq-99-acura-cl-cooling-fan-3-0-does-nt-work-except-when-i-wiring.html

 

Got it, every diagram i could find was pointing to the sensor on the thermostat but i checked the rad and there is a control sensor in the bottom passenger side, jumped it and fans came on so i guess im replacing that sensor