Two Stage Fan Switch - Simple Solution?

[v8s4me]

This is TVR's idea of how to reduce the current and slow down the fan on the first speed setting...



Some marks for effort I suppose, even if it is a fire risk.

Would connecting THIS to the first stage do the trick?

Edited by v8s4me on Monday 27th February 10:20

[v8s4me]

Penelope Stopit said:

.... you could engineer something so as to be able to fit a resistor inside the heater box so that the circulating air will cool it....

I was planning to locate the resistor inside the heater air intake scoop for that very reason. Any suggestions as to what the resistance value might be though?

[v8s4me]

v8s4me said:

....Would connecting THIS to the first stage do the trick?....

Yes it would!

Dead simple to connect and reduces the voltage to the fan effectively to give a real slow/fast.

Slow...



Fast....



The ballast resistor does get quite hot on the slow setting so the only real issue is where to mount it.

Edited by v8s4me on Friday 3rd March 21:46

[v8s4me]

I was thinking of getting another one for the instrument lights so I could try two in parallel to see how much cooler they are. Given how much effort it's taken so far to keep the rain out, not having to run wires through the bulkhead would be good.

[v8s4me]

adam quantrill said:

...how about putting it in the air path into the heater box? Then air will be drawn over it by the fan, cooling the resistor and warming the air into the bargain.....

Great minds think alike

v8s4me said:

.....I was planning to locate the resistor inside the heater air intake scoop for that very reason...

adam quantrill said:

..... Then air will be drawn over it by the fan, cooling the resistor and warming the air into the bargain....

Hadn't thought of that benefit though. I could also make toast soldiers with it

phillpot said:

....Out of interest, did the resistor wire (in first photo) not work?....

Not really, no appreciable difference in fan speed. Probably just as well considering how much heat the ballast resistor is chucking out.

Penelope Stopit said:

....No you can't fit that ballast resistor to create a 1st speed. ....

Edited by v8s4me on Friday 3rd March 20:42

[v8s4me]

Interesting idea. But how would that work with the thermal fuse? The ballast resistor is getting very hot so would there be too much current for the HRS element to handle?

[v8s4me]

Rockettvr said:

....... I certainly wouldn't be happy to find a load of non standard wiring stuffed in behind the dash and have to unravel what its for....

I thought that was part of the fun in buying an old TVR

[v8s4me]

Penelope Stopit said:

....The Heated Rear Window Element could be wired in series with the fan switch for a slow speed

The resistance of the HRS element on my car is 4 Ohms, twice that of ballast resistor. So unfortunately that wouldn't leave a lot of volts to work the fan and possibly overheat the screen. Good idea in theory though.

[v8s4me]

Penelope Stopit said:

....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...

Not the case in practice I'm afraid. It rains here in summer so sometimes the roof has to go up and the poor ventilation means the windscreen can steam up, especially sitting traffic. So we need the blower the keep the screen clear.

[v8s4me]

Penelope Stopit said:

.... and the heat produced from the HRS would not be a problem would it ...

I thought we were talking about a convertible?...

Penelope Stopit said:

....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...

Now I'm confused

[v8s4me]

Alpha Omega, you appear to share the same member page as Penelope Stopit. Are you the same person? Just curious.

Anyway, for anyone wondering about the original question, yes you can use a simple ballast resistor like the one shown above to reduce your fan speed. The only issue is where you mount the resistor because it does get a bit hot .

[v8s4me]

adam quantrill said:

........Try one of these: Governor...

Thanks for the tip. Unfortunately I've "adapted" my switch panel now so I've got an auxiliary rad fan switch where the ciggy lighter was. Your little gadget might have fitted the ciggy lighter hole and I could have used the heater control slot for the auxiliary fan. Never mind, I'm sure there will be a next time. My fan draws just over 12A on full power, this unit is rate at 10A so would it be OK? At that price I think I'll buy one anyway and experiment with it. What's the worst that could happen?

Edited by v8s4me on Monday 15th May 20:37

[v8s4me]

Alpha Omega said:

...... I am also a great believer in correcting errors and stand to be corrected or educated as and when.....

Alpha Omega said:

...... I am about to build a alphaome.ga website....

An alphaome.ga website

Alpha Omega said:

......my new website .....

This one?



What will it contain?

[v8s4me]

Rockettvr said:

...Thought you might have a bit of god complex going on .......

Well two persons-in-one is almost there