1999 park avenue cooling fan problem
 

My cooling fan will not run. Only runs when i turn on air conditioner. When i start car, the fans will not run when the car gets hot. Temp will rise to 200 degrees and fan will not kick on. When i turn on the air conditioner the fans run. I can then shut off the air and the fans will continue running. When car cools and i start it again without the air on, the car will warm to over 200 degrees and the fans won't run. Relays are all good. I replaced the coolant temp sending unit. Any ideas?

I believe there are two separate switches that control the cooling fans. I will check further and get back to you. hanky

Generally the low speed coolant fan does not come on until the coolant temp rises above 212 degrees. The high speed coolant fan comes on when coolant temp rises above 226 degrees F . The coolant sensor sends the signal to the Powertrain Control Module which controls the coolant fan relays (2) . If you want to, check the underhood fuse block to make sure one of the maxi fuses is not blown. I believe its 40 Amp.
Coolant concentration should be at least 50/50 and you can have the radiator cap pressure tested . it should blow off at 15 PSI. Let me know what you find. Thanks, hanky

Thanks...the fan did kick on at 210 degrees. Problem solved. Thanks.