RX400h engine fan constantly on when A/C selected

[nickrw]

Hi all. My 2007 RX400h has recently developed a strange fault. The electric fan in the engine compartment comes on all the time when a/c is on in the car, but only when the engine is running! It certainly does not normally do this. If I turn the a/c off but leave heating on the fan will stop. If the engine stops eg at traffic lights, the fan will stop, but then start again as soon as the engine fires back up. I am not referring to the interior cabin fan, which is working correctly, but one in the engine compartment like the radiator fan.

I don't think it's the radiator fan, but there's another on there next to it which I cannot actually see.

My local garage actually have no idea so I suspect I'll need to tell them what the fault is!

[Texas]

You may not have noticed it before but most cars, when AC is on the (or a) fan runs constantly, thinking about it then AC is normally used when the ambient temperature is up and it makes sense to cool the condenser for the AC system if it warmer outside to assist its cooling effect.

paul m.

[DanD]

2 hours ago, nickrw said:

Hi all. My 2007 RX400h has recently developed a strange fault. The electric fan in the engine compartment comes on all the time when a/c is on in the car, but only when the engine is running! It certainly does not normally do this. If I turn the a/c off but leave heating on the fan will stop. If the engine stops eg at traffic lights, the fan will stop, but then start again as soon as the engine fires back up. I am not referring to the interior cabin fan, which is working correctly, but one in the engine compartment like the radiator fan.

I don't think it's the radiator fan, but there's another on there next to it which I cannot actually see.

My local garage actually have no idea so I suspect I'll need to tell them what the fault is!

What makes you think this is a fault? 

[nickrw]

I've had the car for years it's only just started doing this. I often drive with the radio off, and at low engine revs I can clearly hear the electric whirring when sat in the car. As soon as the car stops at traffic lights and the engine stops, the electric fan stops too. It's quite loud, it's just the same as the electric radiator fan, you really notice it when it's running.

Perhaps I need someone else with the same car to test theirs to see if it's the same:-

Turn stereo off
A/c switched on (yellow light on on the climate page on LCD)
Rev the engine a little (or turn heated seats on the keep engine running)
You should easily hear the loud fan at front of engine
Allow engine to stop, fan stops
Turn off a/c yellow button on LCD (keep heating on) - the fan will also stop

I'm going out to the car right now because you guys are making me paranoid...

[nickrw]

Well that fixed it! I went out to video it, and of course it's not doing it any more.

As you said Paul it's probably just coming on when required to cool the a/c compressor, which it doesn't need to do right now as it's 7 degrees outside. It's odd that I've not noticed this before in six years of ownership!

Cheers for the very quick responses by the way!!

[Texas]

Time to get worried is when it Don't come on.......ever!

paul m.