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SP250 electric fan thermostat

andrewatcourtfarm
Posts: 24
Joined: Sat Jun 24, 2017 10:40 am
Location: Gloucester, Gloucestershire.

Re: SP250 electric fan thermostat

Post by andrewatcourtfarm »

The thermostat is fitted in exactly the same place as yours. The wiring is cable tied to the cross member and the control unit is quite near the battery. A real puzzel.

Vortex O'Plinth
Extra-Wise Man
Extra-Wise Man
Posts: 1065
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: SP250 electric fan thermostat

Post by Vortex O'Plinth »

Is your car still positive earth or has it been converted? With negative earth systems there is rarely an installation problem, but if positive earth Revotec include this warning in their installation instructions..
Capture1.JPG
My system is still positive earth and the fan is wired (via the relay) directly across the terminals of the battery. The thermostat negative supply is taken from the ignition switched feed at the fuse box and the positive earth made separately to the chassis.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

andrewatcourtfarm
Posts: 24
Joined: Sat Jun 24, 2017 10:40 am
Location: Gloucester, Gloucestershire.

Re: SP250 electric fan thermostat

Post by andrewatcourtfarm »

Nick.
Thanks for your comments. The thermostat is fitted in exactly the same place as your's. I have rewired it using double screened cable earthed at both ends. This has helped but not completely solved the problem. Most of the time the fans comes on and goes off at the correct temperature but occasionally it comes on well below temperature and will not go off again until I switch the ignition off and switch it on again. It will then work OK for a while. Before I rewired with screened wire the fan would always come on below the desired temperature and stay on, so I am convinced the problem is due to RF interference.

I need to check whether my spark plug leads are copper or carbon. I have tried to find out what might be causing the interference on Google and apparently carbon leads emit a dramatically lower signal. Do you know if you have carbon leads on your car Nick? Does any one know if I can buy a set for the SP250 already made up, terminated etc?

Andrewatcourtfarm

P.S. I cannot remember if I said this in a previous post but the car has been converted to negative earth and the Revotec thermostat has been wired exactly as they recommend. I spoke to Revotec and they thought the problem might be caused by interference.

Vortex O'Plinth
Extra-Wise Man
Extra-Wise Man
Posts: 1065
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: SP250 electric fan thermostat

Post by Vortex O'Plinth »

andrewatcourtfarm wrote: Mon Aug 07, 2017 12:26 pm I need to check whether my spark plug leads are copper or carbon. I have tried to find out what might be causing the interference on Google and apparently carbon leads emit a dramatically lower signal. Do you know if you have carbon leads on your car Nick? Does any one know if I can buy a set for the SP250 already made up, terminated etc?
My HT leads are copper Andrew. You can get a set of suppressed carbon leads from Larkspeed, but note that the coil connection is the 'acorn' not the push-in type.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

andrewatcourtfarm
Posts: 24
Joined: Sat Jun 24, 2017 10:40 am
Location: Gloucester, Gloucestershire.

Re: SP250 electric fan thermostat

Post by andrewatcourtfarm »

Thanks Nick

andrewatcourtfarm
Posts: 24
Joined: Sat Jun 24, 2017 10:40 am
Location: Gloucester, Gloucestershire.

Re: SP250 electric fan thermostat

Post by andrewatcourtfarm »

Just to remind forum members; I have a Kenlowe fan controlled by a Revotec thermostat (The Kenlowe thermostat appeared not to be working) and I tried lots of things to get it working to no avail. I suspected RF interference due to my Pertronix ignition and/or Flame Thrower coil even though other members were using exactly the same components with no problems.

The problem with the thermostat not working properly got worse. The fan would come on within one minute of the the engine starting from cold.

Today I fitted a set of carbon HT leads supplied by Autocar the same company that supply Lumenition electronic ignition. This appears to have completely solved the problem and makes me wonder if the original Kenlowe thermostat was being affected by RFI.

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