QuestionQUESTION: 2000 Max GLE - both of my coolant fans come on full blast anytime I select "Auto" on the climate control no matter if the engine is warmed up or if I just start the car cold.
The fans turn off if I select "Econ" or go into a manual mode.
I suspect when you choose "auto" that the system uses the AC (even though I set it to 85 degrees) but I do not think both fans should come on especially when the engine is cold?
Would this be temp sensor or a fan control?
ANSWER: Khanh,
The fans come on when aircondition is selected as the same relay grounds the fans as does the airconditioning compressor. It is not controlled by the engine being hot or cold. It is if the compressor is commanded on. Look at the compressor and email me back and let me know if it is activating.
---------- FOLLOW-UP ----------
QUESTION: Hi Von,
Thanks for your quick reply. The compressor is activating under "Auto" mode only, not under "Econ" or "Manual" mode.
The only thing I don't understand that both fans come on in such a high speed (just like a jet is taking off)and loud which they never did in the past 9 years until last week.
AnswerKhanh,
The relays that control the fans are independent and tied together. First, the one that runs when the car gets hot is controlled by the relay that is grounded by the computer when the temperature switch grounds. When the airconditioner comes on the other fan will activate. When the computer senses more heat the airconditoning system will ground both relays. You could play with the relays and see if one is stuck on. But, I bet both are fine since they turn the fans on and off in and out of econ mode and airconditioning mode. I would suspect the brain for the climate control since this is a known issue with the Maxima and the automatic climate control. The brain is the head unit that you use to activate the climate control with. Now, to test this out get a test light and go to the relay box and find the two relays for the fans and use the probe to find the circuit that grounds the relays. When you cycle the airconditioning you will probably see that it is commanding both relays to ground. I am pretty sure it is the control box. But, there is one more this that provides information to the computer to ground both fans and that is the pressure switch. Too much pressure equals too much heat and that is when the computer is supposed to turn on both fans for the airconditoner. So, check the pressure switch to see if it is stuck before getting the control. As old as it is a wrecking yard is going to be the best source for the control or ebay or on-line.
