Radiator cooling fan problem...

[DaveJP]

Radiator cooling fan problem...(update)

'91 with 65k miles. My radiator cooling fan is not engaging as normal. If the car is idling for a long period (10-15 minutes) the temp slowly rises and the fan does not kick on. Once I start driving, the temp returns to normal. Cooling system is fine..no leaks, no air, thermo is good. I checked the fan motor itself and it is operational. I did a Prime search, but did not come up with much..Any ideas on the cause?

Thanks.

 

[hlweyl]

Hi Dave, there are several relays to check for the radiator fan. Download the service manual http://www.nsxprime.com/FAQ/Reference/1991_svcman/1991_svcman.htm and read section 32. It gives a detailed description of the system and some troubleshooting also.

One question: when you say your temp slowly rises, how far does it rise? Does it go near the red? It should stay just under the halfway mark and be rock steady. The only times i've heard it going higher is when at the track in high temps.

 

[NSX-Racer]

Sounds like a bad thermostat.

 

[DaveJP]

Thermostat checks out fine. The temp keeps going up (my guess is that it would overheat eventually due to the fan not activating).

 

[NSX-Racer]

AFAIK there are two thermostats. One for the fan and one for the water circulation - did you check both? You may also try to check the fan by directly (improvised) wiring it to the battery - should do no harm.

 

[nsx24]

What do you mean there is 2 thermostats? I have never heard that. I am having similar problems but I am going to change out the thermostat and see if that can cure my problem, but now you say there is 2??????
Any help would be appreciated

 

[DaveJP]

Thanks for the responses...The fan motor works fine (wired directly to the battery to test). As for the "other" thermostat, it is actually a temp sensor in the engine bay that sends a signal to the fan control module. I have not checked this sensor yet. The fan control module sits behind the seats on the firewall..I suspect this may be the culprit and was wondering if anyone has had one fail. Looks pretty simple to replace, but not sure what the cost of this part is.

 

[NSX-Racer]

So to be precise: The real thermostat under the front bonnet opens and shuts the water circulation (I did overrun it at my track car), the other is a temperature sensor as Dave JP described - sorry for my bad technical english.

 

[hlweyl]

So to be precise: The real thermostat under the front bonnet opens and shuts the water circulation (I did overrun it at my track car), the other is a temperature sensor as Dave JP described - sorry for my bad technical english.

No offense intended, but maybe there is a terminology difference... when I changed my thermostat last year, it was in the engine bay under the throttle body. There is no thermostat in the front of the car that I know of. I just looked through the online service manual and I don't see a thermostat in the front.

I would still contest if this were a thermostat issue (which usually fail in the open position), the car wouldn't be overheating. In that situation, the car would most likely run cool. I'm still thinking probably one of the relays to the fan. You can always take the thermostat out and test it to rule that out. The test is described in the service manual.

Good luck

 

[DaveJP]

Re: Radiator cooling fan problem...(update)

Problem solved. I installed a new fan control module and the fan now works as normal. For those that have mysterious temp problems, you may want to check the operation of the radiator cooling fan. You won't notice that it's not working unless you sit in traffic for 15+ minutes. I would imagine you also might notice it with some hard track driving.

Also, I opened up the old module...You guessed it..leaking/failed caps.

 

[NSX-Racer]

Glad it worked out so fast - shouldn't be too expensive, right?

 

[DaveJP]

Not bad at all...New module was $120. I can probably repair the old board for under $10. I'll keep it as a spare or get rid of it if someone else needs one.

 

[Stephen@NCAutoUSA]

Bumping this up and wanted to share for future owners. Here’s my details.

Problem solved.

Issue: temperatures would rise at idle stop but were fine when driving.

Solution: re-soldered the joints on the radiator module. “This item is a black box next to the main relay behind the rear bulkhead panel”

My car is a 91 and I had to solder the main relay box a few years ago and I just took care of the radiator module.

 

[docjohn]

Every time someone brings back a really old thread I shed a little tear for all the great long gone members here...:frown:

 

[goldNSX]

Every time someone brings back a really old thread I shed a little tear for all the great long gone members here...:frown:

So true.

 

[tucsonsx]

Me too.