LocostBuilders - powered by XMB

Additional fan switch wiring

steve8274 - 25/4/14 at 05:17 PM

Hello all
I am considering putting a switch in my car for the fan. At the moment, it operates via a fan switch in thermostat housing.
Is there a way to have the fan come on with thermostat switch and switch in car?
What type of switch would I need and could someone say or draw how to wire it?
Thanks in advance
Steve

omega 24 v6 - 25/4/14 at 05:26 PM

Just connect them ( the switches) in Parallel. this will work if its direct control from the fan switch OR from a fan relay. If its direct them make sure you use a switch capable of taking the current required.

steve8274 - 25/4/14 at 08:29 PM

Thanks for the reply.
However what you said means nothing to me😃
I have a very basic understanding of wiring at best. Have you a diagram or could you expand?
How would I know how much current my fan takes for the switch?
Thanks again
Steve

HowardB - 25/4/14 at 08:32 PM

like this,..

[img]
Description [/img]

britishtrident - 25/4/14 at 09:10 PM

All you will achieve is make the fan operation less reliable, just choose the correct fan switch and supply it from a permanent on supply.

omega 24 v6 - 25/4/14 at 10:49 PM

What BT has said is quite true. But it does help ( the extra switch that is) in an emergency if the stat switch happens to fail. Some of the cheaper ones are very poor and fail.

snowy2 - 26/4/14 at 06:17 AM

This exact question has been covered with a comprehensive wiring diagrams here......Wiring article
Hope it is of help....its one of two articles on the link..the second one is the one you want.

snowy2 - 26/4/14 at 06:40 AM

quote:
Originally posted by HowardB
like this,..

[img]
Description [/img]

if your using a relay you don't need a 30A switch. a micro switch will activate a relay safely. if you need a 30A switch you dont need a 30A relay there is no point.

do you know i really should read the post more carefully.....you say that on your diagram....ooops Sorry. Dave.

[Edited on 26/4/14 by snowy2]

snowy2 - 26/4/14 at 06:47 AM

quote:
Originally posted by britishtrident
All you will achieve is make the fan operation less reliable, just choose the correct fan switch and supply it from a permanent on supply.

not true....many production cars use relays to switch the fan, and adding a manual switch in parallel to the thermostatic switch will have zero effect on it's operation. the manual switch just does the same job the thermostatic switch does........turns on the relay.
In fact using a relay actually makes the thermostatic switch more reliable over the long term, how its switched on will not affect any component in the given circuit.

omega 24 v6 - 26/4/14 at 09:45 AM

I think the point being made is if you forget to turn the manual switch off when you are on the open road then it is counter productive to air flow through the radiator.

steve8274 - 26/4/14 at 09:52 AM

Thanks for all the replies. Will give it a go this weekend. If I wire it with a warning light then hopefully I shouldn't leave it on
Steve

snowy2 - 26/4/14 at 07:19 PM

My circuit above also illuminates a warning lamp on the dash, either with the manual switch or when the thermostatic switch operates. comforting when in heavy traffic.

adithorp - 26/4/14 at 07:37 PM

quote:
Originally posted by snowy2
My circuit above also illuminates a warning lamp on the dash, either with the manual switch or when the thermostatic switch operates. comforting when in heavy traffic.

I did that using an LED. Unfortunately the wind blowing the fan around caused the motor to act as a dynamo and the LED flashed above 30mph. I had to put a diode in the line to prevent it back feeding.

snowy2 - 28/4/14 at 05:39 PM

because my circuit is with a relay the same problem wont occur (the relay isolates the cct.)