I have a 2010 IS250 and the cooling fans never come on. It seems like a fuse issue as the low speed doesn't start when the AC is turned on and the high speed doesn't start when it gets to temperature. I have checked the fuse under the hood and it is fine. What should I check next? If it worked in one of the situations (AC or high temp) I would think it could be a relay but what are the odds that both of the relays are bad?

 

Go for a quick drive to warm up the car to operating temp. Then park the car with the AC off. With this outside heat it should come on faster. Wait to see if the fan will come on. If you have a scan tool. It will be around 205F when it kicks on. If the scan reads that temp, and if the fan doesn't kick on. Then maybe you do have an issue.

 

I don't have a scan tool but the fan doesn't start when the temperature goes beyond the halfway on the scale. The temp will continue to rise without the fan starting.

 

I have checked power at the fans, when it gets to temp or when the AC compressor engages I get 12V (actually 13.5V) at the fans. Guess the fans are bad, could it be anything else? Any other way I can verify the fans are bad before I pull them?

 

Maybe the relays?
https://www.clublexus.com/forums/is-...-location.html


I would check power to each fan directly to a 12V source first before getting new ones.

 

https://www.clublexus.com/forums/is-...ssembly-2.html

 

What can I do to add a 12V source to the fan motors. It doesn't seem like it would be a relay issue as the fans are getting power during the appropriate conditions. I tried to spin the fan with my multimeter leads attached to see if the DC motor would produce a voltage but I couldn't tell if my leads were actually on the connectors. So that was a failure.

 

It seems pretty odd to lose two fan motors. Do you understand how the relays work? Two pins are to power an electromagnet. Two pins are the relay that carry current to power the fan motor. Of those two pins, with the car on, the relay has +12v on one side and the other goes to the fan motor. With the relay out you go from ground to lead feeding the motor and do your spin test for DC volts.

With the relay in, you can disconnect a fan and place a halogen lamp out there as a small load and turn the AC on. The lamp should light. Mind you if low on freon, the whole system is disabled to protect itself.

 

2013fsport - Electricity definitely isn't my strong suit but I understand the basics. It does seems odd that I would loose two fans. I understand what you are saying about using a bulb to test it but that is basically what I did with the multimeter. I disconnected the fan and tested the harness, I am getting 12V when the AC is on or when the car is at temperature. Did that accomplish the same thing as the bulb test or am I missing something?

 

A volt meter takes no current to create a 12v signal. Think of it this way; a 40 gauge wire strand can show you 12.75v. That microscopic strand will not light the light much less power a 25 Amp fan. That is the difference between voltage and current.

Current (amps) do the work. Do @2013FSport if you need quick input.

 

I rigged up a light bulb and it lit at the appropriate times. I also tried to get the fan motor to turn by hooking it directly to a small moped battery and it would not turn. I believe I have confirmed the fan is bad. Thanks for everyone's help.