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nickw
26-05-04, 07:36 PM
Can anyone help with the wiring in of an override switch for a Kenlow style fan. The one fitted (not sure what make) has a thermostat switch which works OK, although an override switch has been suggested/recommended, particularly when stuck in traffic in this hot weather?!!

Any help would be much appreciated.

Thanks, Nick

Purple AK
26-05-04, 08:22 PM
Hi Nick.

Assuming the thermostatic switch switches the fan via a relay, which it should, you can simply wire an overide switch across the two terminals of the thermo switch.

Cheers

MacGD016
26-05-04, 08:52 PM
I agree with Chris, if there is a relay switching power to the fan you can connect a new lead to the relay coil from a switch. However, if there isnít a relay the attached diag might help.

Mac

nickw
27-05-04, 06:56 PM
Hi Chris & Mac

Thanks for the response and I think I know what to do?!

The system does have a thermal switch with a live and earth connection. Using a simple on/off switch I need to connect to the earth and positive respectively which will then provide the override when needed. Should I put an in line fuse on the live connection?

I don't mean to be vague but just want to be clear I am wiring up the right thing. For reference the unit is a Clovafan.

Cheers, Nick

Purple AK
27-05-04, 07:06 PM
Hi Nick.

Are you saying you only have two connections on the thermal switch? If so the live is coming from the fan which is permanant live, and is earthed by the switch. If this is the case then you only need to connect the overide switch to those terminals.
HTH Cheers :)

MacGD016
27-05-04, 07:42 PM
Hi Nick

The thermal switch will show live on one side and ground on the other when it is cold and live on both sides when hot. As mentioned in other posts it either switches the fan directly or it drives a relay that provides power to the fan. The live side may come from the ignition or direct from the battery, if its from the battery it should be fused otherwise probably not. If the wires to the thermal switch are thin it is likely that there is a relay and if they are fat it is more likely that it directly switches the fan.

All of which is getting very confusing so here are a couple of diagrams that show the various options and I hope will explain things better. As itís a Clover system it may well be driven by a relay so the last diag could be your answer.

Mac

PS you need to view the attachment in full size to read it

nickw
27-05-04, 09:51 PM
Thanks for the further information and diagrams. I'll compare these with the setup on the car and wire accordingly.

One for Saturday morning, afternoon, evenging......

No, hopefully it should be straight forward.

Cheers, Nick

Kevin W
07-06-04, 06:09 PM
Mac,
Maybe I misunderstood, but I thoughtthe ignition switch shouldnt figure in the fan wiring ?- i thought it should be a continuous live, so that the fans stay on when the engine is hot, but the ignition switch is off, such as leaving the car parked up on a hot day after a long run.

Kevin

MacGD016
07-06-04, 07:18 PM
Kevin

There are a number of schools of thought on this, on the one hand itís a good idea to run the fan when the engine is switched off to cool it down but on the other this will drain the battery a bit. Some mainstream manufacturers put a timer in to run the fan for a couple of minutes. I think this would be my preference but I donít have a timer handy at the moment. So really its up to you.

Mac

hfbradley01
07-06-04, 09:20 PM
I would recommend fitting the relay inside the car behind the dash so that it is easy to fit a bypass switch onto the dash panel.

It makes it more convenient and I don't like relays in the engine bay if it's avoidable.

Cheers

Howard

agwebsites
07-06-04, 10:43 PM
But if you have a thermostat switch why should you need a manual one, even on hot days etc. Surly if it is set correctly the fan will just come one when itís needed. Having never come across a production car with a manual override and using a Kenlow fan myself with a thermostat switch. Maybe Iím missing something but I just donít see the point of fitting a manual switch.

If you put the thermostat sensor in the lower pipe feeding the rad then the hot water rises and the water would have to be really over temp for the fan to run for very long after the engine is turned off, removing the need for a timer. The other consideration is that the fan running on can activate your alarm if one is fitted.



Cheers,

Andy

Purple AK
07-06-04, 11:14 PM
The Thermostatic Switch should be in the top hose so that the engine runs at optimum temperature. However it is desirable to have a manual overide for traffic situations when the water pump is not moving the coolant around at normal speed, and you have no airflow through the rad. Nice to have control over the situation.

Cheers

Purple AK
08-06-04, 09:49 PM
Or, In the case of Kevin T last week, nice to have a back up when the thermo switch goes wrong.
Cheers