Fans on all the time!!!

[Jitzz]

Hi all,

Just a very quick request for some advice...I've got a 4.2 cerb which I've been working on

I've just replaced my rad and changed the rubber hoses to nice fancy silicon ones - which look really cool!
Also flushed the system and bled through

The problem I have is the fans are constantly on !?!? As soon as the engine is turned on even from cold

Is this just a temp switch issue of so ring more sinister

Any guidance would be greatly appreciated

Thanks a lot
Jitzz

[billybradshaw]

I think it could be down to the sensor that supplies the ECU with temperature data. Check to see that it is connected properly, no broken wires, etc.

The sensor is located (screwed in) in one of the metal coolant pipes near the thermostat.

HTH

Ian

[TheRainMaker]

Like above, fans will run if the sensor is unplugged.

I would start there :-)

[Jitzz]

great thanks guys!!

the senor is plugged in and connected....so.do you think it may be faulty, as it all worked perfectly before the radio work

thanks for the speedy response guys

cheers

jitzz

[aide]

The connectors on the temp sensor oxidise. It gets really wet around the area where the sensor is fitted. The copper connections turn green and the electrical connection degrades.
You can clean up the connections or fit a new sensor.
In either case, some contralube on the connection will stop this from recuring.
HTH!
Aide

[Jitzz]

great thanks Aide,I'll give that a go and clean then up...if not, then I
guess a new sensor it is

cheers

jitzz

[ukkid35]

You can check whether the sensor is connected and working properly by hooking up to the ECU using Aide's Android App. If you find you need a new sensor the one you want is Bosch 0280130026, for about £9 on eBay (or more than double that from a TVR parts supplier).

[Jitzz]

great thanks for the part number ukkid..I'll probably get one anyway as it looks like it's never been changed

the app look interesting..I'll download and try that too!!

much appreciated

cheers

jitzz

[Englishman]

Do you have an ACU fitted? If so, could be the trinary switch, TVR P0031. I've had this fail twice on TVR's switching the fans on.

[Jitzz]

hi englishman
yes I do have an AC unit fitted....but not been working as I've not regassed it over the years...I've now taken the ac rad out.

really daft question ...but what is a trinary switch and where is it located????

thanks

jitzz

[Englishman]

I'm sure there are lots of threads on this, but here is one with a picture from the Tuscan. Expect it is in a similar position.

http://www.pistonheads.com/gassing/topic.asp?h=15&...

Description taken from the TVR Parts website:

This switch controls a number of functions of the air conditioning system and is mounted in the receiver drier. As with most work on the air-conditioning system the refrigerant will need to be removed prior to replacing the switch.The trinary switch contains three pressure switches; high, low and medium. The trinary switch has three functions: 1. To disengage the A/C compressor clutch if the refrigerant pressure falls below the "minimum" specified value. 2. To disengage the A/C compressor clutch if the refrigerant pressure exceeds the "maximum" specified value. 3. To switch the cooling fan to high speed if the refrigerant pressure exceeds the "high" specified value. This is a high quality trinary switch and comes with the correct o ring ready for fitting. Should the trinary switch require replacement or the system opened then the reveiver drier unit should also be changed.

You can check if this switch is permenantly on by simply disconnecting it.

[Jitzz]

brilliant advice mate..thanks so much, I'm on it this morning, with the checking routine

very much appreciated englishman !!

Cheers
jitzz