Revotec fan wiring on a TR6

[Atl TR6]

Purchased a Revotec fan kit and it appears they aren’t too common on this side of the ocean. In fact, the only place I really found any conversation about them was on this site. Mostly positive.

 

Attached is a diagram of the planned wiring. Listed below are some of the key points :

• The relay that came with the kit has the trigger jumpered from the main power wire. I’m thinking of changing the trigger to be powered with the white ignition wire at the fuse block. This would keep fan from running with the key in the “off” position.
• The main power would be provided with a jumpered wire from the brown fuse wire to unused #4 fuse spade. Another option might be to run wire from unused spade on wire block on positive power cable that runs from battery to starter to the #4 fuse, but this would add extra wiring I'd like to avoid.
• Instead of the Revotec manual switch, I'm planning on using a lighted 21 amp switch mounted to the dash. The light circuit is independent from the fan power circuit. If the relay went "kaput", I could still run fan. When fan runs on "auto" the switch turns "white". Flip the manual switch "on" and it turns "red".
• Fan specs states it draws 9.6 amps at full speed (1500 cfm), and 10.8 amps at startup (0 cfm). I believe the 16 AWG and 21 amp switch can handle this.....but to be honest, i'm not 100% sure.

Please feel free to critique diagram, as I’m not an electrician by trade. Thanks for any input/suggestions you may have.

Edited November 23, 2016 by Atl TR6

[barkerwilliams]

".......This would keep fan from running with the key in the “off” position. "

 

 

​If I have understood the above correctly, but the fan must be be able to run with key in the off position, i.e. when you pull up and park and remove the key the water temperature rises and the fan almost always starts up after a few seconds and lowers the water temperature, otherwise radiator will boil over. Fan needs an always-live, fused connection.

 

 

Additionally the ignition switch "struggles" to carry the current for all powered devices and the additional 10amps passing through its contacts would not help.

 

 

 

Alan

Edited November 23, 2016 by barkerwilliams

[RobH]

According to the circuit here for a '74 car:

http://www.advanceautowire.com/tr2506.pdf

the existing brown wire to the fuse box already carries auxilliary lighting, horns, plus the headlamp main beam, so its not a good idea to use that for an additional 10 amps load as that would almost double the current the brown wire carries. You could replace the existing brown wire with a heavier one but that would need alterations to the loom. It would be better to run a separate new wire to supply rather than to jumper at the box.

 

Your scheme does show the ignition switch carrying just the relay coil current plus anything taken by the fan controller so probably a fair bit less than an amp extra in total.

 

I'm not convinced that the fan actually is needed once you stop as Alan says -- although the temperature might rise a bit, the original mechanical fan doesn't run and cars do not boil as a result. I would agree that its better if the whole thing is powered directly on a dedicated supply to avoid any extra load on the ignition switch, however small. I guess by 'turns white' you mean the light in the switch is normally off and that it only goes on (red) when the switch is operated manually - or has it actually got two lamps in it one white and one red ?

Edited November 23, 2016 by RobH

[astontr6]

+1 for Alan,

 

As Alan says do not use the ignition s/w to power the fan as this s/w is subect to causing electrical fires, as some of our group members have found out. I use a separate power supply from the battery via an extra fuse block, which also is used for the pump, head lights and spot lights, all via relays, switched by the ignition s/w. but you can of course have a live fused s/w as an override. Make sure you use the correct rated wire and wire colours, on all connections and use crimp/solder joints. In my time I have had to remake too many crimp joints on other peoples cars which were poorly done.

 

Bruce.

[RogerH]

Hi Rob,

regarding the electric fan over running with Ig off.

 

With the mechanical fan fitted the engine receives some cooling effect when parking or driving slow to be parked up.

This must have some effect but not sure how much.

 

The electric fan helps to remove the excess heat with no ill effect to a normally maintained car.

 

But it is probably 6 of one and half a dozen of the other.

 

Having the fan powered through a relay controlled by the Ig switch would put virtually no load on the Ig switch

 

Roger

[Lebro]

My fan goes off with the ignition, & I have never had "boiling over problems when switching off.

 

Bob.

[peejay4A]

Mine's allowed to run after switch off and I've never had boiling over problems either

[astontr6]

Hi Alt,

 

Wire size? You quote using 16 awg, (1.3mmsq) too me that is a bit small. I would use 2mmsq (14 awg) thin wall automotive wire, rated at 25 amp.

 

Bruce.

[Atl TR6]

Thanks all for the feedback. Really appreciate it. Goal is know what I’m doing before I start

 

I’ve read many posts on switched vs unswitched power to fan relay. Here in the hot southeast USA, I’m probably better with switched to avoid possible battery drain from it running when car is turned off.

 

The red main power wire that Revotec uses to feed the relay is labeled 16 AWG, so I was going with the same, unless there is an advantage to 14 AWG prior/upstream. The wires for the Revotec trigger appear to be 18-20 AWG…they are much thinner.

 

The ignition white circuit wire will only power relay trigger, not the fan.

 

To clarify the toggle switch:

• The toggle is unlighted when fan is not running.
• When the fan controller kicks on, the switch turns white.
• When I flip manual switch on, it turns red….which I’ll use as my reminder to turn off, switching it back to auto

 

“the existing brown wire to the fuse box already carries auxilliary lighting, horns, plus the headlamp main beam.”

I do have the headlight on a relay now, so brown wire only powers the trigger to headlights relay. The headlamps would be the big draw. I’m not sure how many amps the interior lights draw. Perhaps it would be best to run a separate power wire to vacant fuse #4. This is what I'm most unsure about.

Edited November 23, 2016 by Atl TR6

[RobH]

OK Bruce, thats different. If the headlights are powered separately now, there will be around 10 amps spare capacity in the existing connection to the fuse box. The other loads are already allowed for and the headlamp relay coil won't take very much so you should be fine with the existing wire and a link as you proposed. Of course the advantage of running a heavier wire than 16 awg would be in reduced voltage-drop but if the run is short then that gain isn't great. 16awg has sufficient current rating so its not a safety thing. 6 feet of 16 awg copper will drop about 0.25 volts at 10 amps and the wire is dissipating 2.5 watts along its length. If you went to 14 awg the drop would be about 0.15volts and the dissipation 1.5 watts.

 

Incidentally where does the 'white' side of the toggle switch lamp get its power - is that via the 18awg wire from the fan relay to the fourth terminal on the switch? I guess the connection for the red lamp must be internal to the switch?

Edited November 23, 2016 by RobH

[Atl TR6]

Incidentally where does the 'white' side of the toggle switch lamp get its power - is that via the 18awg wire from the fan relay to the fourth terminal on the switch? I guess the connection for the red lamp must be internal to the switch?

 

The toggle switch will be wired to the feed going into the fan after the relay. The toggle switch has two separate circuits..lights and manual power to fan

 

The White/red light is powered by the 18 AWG (I'll probably switch that to 16 AWG also). The white light can only come on if the fan relay turns on or I switch manual override on which turns on red light. Below are the switch specs

 

https://www.delcity.net/catalogdetails?item=7900065

 

Thanks for the input on load to brown wire at fuse. Sounds like the fan will just replace the headlamp load for the main beam.

 

If I'm understanding the wiring diagram for headlamps:

• the main(high) beam is powered by the brown wire at the fuse box. (this is where I'm getting the 10 amp pickup from headlamp relay I added & can use it for fan instead)
• The low beam is not powered through the fuse box at all, but rather is an un-fused connection through the headlamp switch.

Edited November 23, 2016 by Atl TR6

[RobH]

Yes that seem correct Bruce. I've looked at the data for the switch but confess I'm still confused by this independent/dependent thing. A circuit schematic would be so much clearer. If the lamps are incandescent you should be OK - if they are LEDs they might be polarity conscious so it would be worth checking the switch works as you expect before you wire it up permanently.

Edited November 23, 2016 by RobH

[Atl TR6]

Yes that seem correct Bruce. I've looked at the data for the switch but confess I'm still confused by this independent/dependent thing. A circuit schematic would be so much clearer. If the lamps are incandescent you should be OK - if they are LEDs they might be polarity conscious so it would be worth checking the switch works as you expect before you wire it up permanently.

 

Thanks for input.

 

No schematic on switch.

 

Testing of switch:

• I put jumpers on the toggle switch light terminals and put one on +battery terminal and other on -battery terminal and switch lighted. When I reversed battery terminals, it lighted also.
• absolutely no continuity between the 2 light terminals and the other 2 terminals
• light terminals: continuity in either "off or on" which corresponds to "white & red"
• other two terminal: no continuity in "off" position, continuity in "on" position.

 

I'm thinking I'm good to go on this project. Thanks again for you comments and advice.

Edited November 23, 2016 by Atl TR6

[Pete Cutting]

I was looking for some information on revotec fans fitted to triumphs when I came across this thread.  

if you want an override switch the easy way is just to put a switch between the small blue wire and earth.

If you want a back-up incase the relay fails why not carry a spare relay?  This would avoid chopping up the Revotec loom etc.They're not big or heavy and could even be cabled tied in a convenient space near the fan relay, beside the battery or kept in the boot with your other spares

[MilesA]

37 minutes ago, Pete Cutting said:

if you want an override switch the easy way is just to put a switch between the small blue wire and earth.

Exactly what Revotec advise if you ask them nicely.

Miles

[Waldi]

Hi Peter,

On my car, the override switch bypasses the temperature sensor, not the relay.

By-passing the relay as well is an option, but this will then put the load (current) on the by-pass wiring and switch, so think about wire thickness and fusing that system too then.

Waldi

[Steves_TR6]

33 minutes ago, Waldi said:

Hi Peter,

On my car, the override switch bypasses the temperature sensor, not the relay.

Waldi

That’s the way to do it, as Punch would say.