Radiator Fan always On

[BladesNSX]

I did a search and checked the FAQ regarding this problem.

Whenever I turn on my car, the radiator fan turns on right when I turn the key to second setting, or a couple seconds after. This problem started occuring withing the past week.

I recently added the Science of Speed coolant bottle to replace my OEM bottle; as well as a check on hoses and coolant flush. The temp. gauge stays rock solid just below the mid way point. Car runs absosutely great even in the hot humid Miami conditions. Still, I am wondering if perhaps I have a bad relay or thermostat? If that were the case though, wouldn't I have some overheating issues?

One other thing, My climate control board unit is dead (but sometimes clicks on then off). I have a new CCU unit from BrianK (bless that guy); and will have it installed by weeks end. I wonder if perhaps this may be part of the problem. I doubt it since the Radiator fan should be operated by a seperate relay. Ugh, I dunno.........suggestions?

 

[NSX-Racer]

You checked all the relating fuses under the front hood? Best with a multimeter, not only with your eyes. And of course the fan problem is likely to be a bad thermo-switch (relay) and not a bad thermostate (which is in my understanding in the engine bay). Don't expect any overheating when all works fine again (as long as there is no other hidden problem).

 

[Briank]

Are you sure you were hearing the Radiator fan and not the condensor fans? A Bad CCU can send a bougus compressor run signal which will bring on the condensor fans.

 

[jonas1jp]

Are you sure you were hearing the Radiator fan and not the condensor fans? A Bad CCU can send a bougus compressor run signal which will bring on the condensor fans.

He's right, my condensor fans were running non-stop until I put the new CCU in. Fixed it right away!!

 

[ncdogdoc]

What is the ambient temp there? That combined with the chance of faulty sensors could play a part. Does it do this first thing in the morning, or just when the car has been off for a while during the day.

It has been so hot here in NC lately that my Lexus takes 3-4 hrs to cool down enough that the radiator fan does not come on as soon as the key goes to "ON".

 

[BladesNSX]

Are you sure you were hearing the Radiator fan and not the condensor fans? A Bad CCU can send a bougus compressor run signal which will bring on the condensor fans.

Hmm, Well....Um...to be honest, I haven't a/c for so long.....I kinda forgot what the compressor in the NSX sounds like when it turns on. :redface:

Yeah I've spent many a sweaty day in my NSX. Took a while for me to get everything sorted to get the a/c fixed since I have to replace more than just the CCU.

He's right, my condensor fans were running non-stop until I put the new CCU in. Fixed it right away!!

Great!! Hopefully, when I install the new CCU this problem will go away. However, My CCU seems completely dead. Well, the indicator lights don't come on.......nothing comes on actually. I suppose, that doesn't mean it isn't sending that bogus signal afterall.

What is the ambient temp there? That combined with the chance of faulty sensors could play a part. Does it do this first thing in the morning, or just when the car has been off for a while during the day.

It has been so hot here in NC lately that my Lexus takes 3-4 hrs to cool down enough that the radiator fan does not come on as soon as the key goes to "ON".

Well, it was 105 a few days ago :tongue: Nice and muggy!!

Well this morning I started her up and the fan never came on. I tried starting her this evening and same result. Drove around for about 15 min., got home and turned her off. Turned the key a couple min. later and the fan (compressor?) turned on.

I really think its just the fan. The sensation of power being taken from the engine when the compressor kicks on isn't noticed. Though, again I don't recall if there is a sensation of the compressor kicking on in the NSX. I didn't use the a/c much when it did work.

I will ask the dealer to check/replace the thermo-relay, install the CCU and run a diagnostic after the install.

Thanks for all the advice.

Not just a great car.......great community.

Though I'm tired of the a/c probs but it's cool

 

[jonas1jp]

I bought my car with a new uninstalled CCU. It took me a while, but I got around to doing it. Easy as pie, even for a novice like myself. Took me less than 40 minutes from start to finish. BrianK has got a really good rep around here, get a CCU from him and install it yourself. Good starting point. If that doesn't do it, then come back for more advice. It will still be cheaper than having the dealer look at it. Good luck..