Radiator fan switch

[ditto]

Has anyone else had a problem with the fan switch, ive had 2 go wrong on me now and ive only done a 950 miles, thanks for any advice

Keith

[steve_D]

Hi Keith
Which switch?
The thermostatic or the manual override.
Is this wired with the factory loom and relay?
Steve

[ditto]

Hi Steve,
its the thermostatic switch, if i join the two wires together the fans work,im on my third switch now,im spending more money on switches than petrol lol, i havent got a manual over ride switch, is there wires for this in the loom? because ive just run my own
Keith

[gdr]

Loom is wired for manual override switch, green & black/orange with earth wire for indicator light (on my loom anyway). Are you sure that the problem is the thermoswitch? I got some airlocks in the cooling system such that the temp in the engine would rise to over 100 C without thermoswitch kicking in (loss of pump efficiency, not getting enough hot water through rad.)
Got round this but still prefer to use the manual override in traffic as I think the factory thermoswitch set a bit high.

[steve_D]

Back to my second question.
Is this wired with the factory loom and relay?

Check that the relay is wired correctly. The only reason I can think that the switch would fail is if it is taking the full load of the fans and burning out.
The relay is number 4 wired
Pin 30 Brown Permanent live
Pin 85 Black Earth
Pin 86 Orange/black Rad thermostatic switch
Orange/black Fan override switch
Pin 87 Orange Fan1
Orange Fan2

Steve

[ditto]

Thanks George,
Good point about the air lock, but i dont think so, i boiled some water and dropped it in stuck a meter across the terminals, burnt me hands still nothing,when i changed it the second time i left it running and the fans come on when they should have will go and check out these wires, thanks again
Keith

[bigmack]

I also had trouble with the thermostat switch. I wired in a manual switch. Just be sure to remember to turn it on!
Cheers!
-Mack

[BobM]

Sheesh, there's a coincidence! I just came in here to ask about the thermostatic rad fan switch too!

I went out for a little spin yesterday and the engine got hot while I was fiddling round on the drive, the rad fans didn't switch on and the temp got to 105 on the gauge before I noticed :-(

Back a few months ago I had the opposite problem, the fans were coming on at random temps and not switching off. I assumed water had got somewhere it shouldn't as the problem seemed to go in the warmer/drier weather.

I do have a manual switch, so it's not a massive problem, but I'd prefer to have the auto option before heading off to Le Mans. Anyone know the spec of the switch so I can get one locally from my motor factors?

[gdr]

I'm sure I spotted an ad on Pistonheads last year aimed at the TVR crowd for an adjustable thermoswitch. Remember thinking it might fit Ultima radiator - would need to check threads.
On my Cobra I had a Pacet adjustable switch which used a capilliary probe stuffed into a water hose union. Worked OK and surprisingly did not leak. Also check Demon Tweeks catalogue, they have an adjustable fan controller integral with an aluminium hose adapter.

[ditto]

ive found the wires under the dash, thanks George, just need a switch now.
Thanks Steve i will check the wiring on the relay some time in the week, if i get time, you maybe right, the switch does look a bit black.
Bob the part number is 50110, it comes on at 92 goes off at 82
Keith

[BobM]

ditto said:

Bob the part number is 50110, it comes on at 92 goes off at 82

Any more info than that Keith? Are you talking Ultima part number here? I was hoping to either get a thread size or something like "its the same as a Ford Escort Mark X" so I can get one locally.

[steve_D]

BobM said:

ditto said: Bob the part number is 50110, it comes on at 92 goes off at 82 Any more info than that Keith? Are you talking Ultima part number here? I was hoping to either get a thread size or something like "its the same as a Ford Escort Mark X" so I can get one locally.

Your local motor factor will just open the book and go to that part number as a cross reference.
Almost all rad stats, ours included, are M22 thread.

You can also thumb through the book and find one that opens/closes at temperatures you prefer. It may not have the same wire termination but that is easily resolved.
Steve

Steve

[davefiddes]

If the radiator switch keeps going then there may be some mileage in putting a big diode (1N4005) across the coil of the relay(close to the relay). This will snub the inductive spike which is generated when the relay turns off. You can also put a capacitor across the contacts of the switch (just like the "condenser" on a points ignitions system)...something fast and small like 10-100nF should do... I'll need to phone a friend on that one.

It shouldn't be necessary to go to these lengths but if the contacts are quite fragile and the relay they are driving is quite big then...

[ditto]

Yes Bob, as Steve has said, i got a new one today it is made by another company, but the part num is still the same, hope this is of some help
Keith

[eliot]

Merlin motorsport also do the inline adjustable type also.
www.merlinmotorsport.co.uk/
under cooling.

e.