410 Air Conditioning

[Kevin H]

John,
It looks like it's a bit late now, but did you consider fitting an A/C unit that provided both cooling and heating and routing it through the existing air vents?
Kevin

[John Keighley]

Originally Posted by Kevin H

John,
It looks like it's a bit late now, but did you consider fitting an A/C unit that provided both cooling and heating and routing it through the existing air vents?
Kevin

Kevin, we retained the heater as it works well but also, Vintage Air offer the slimline unit to fit under the dash and for the 410. This is the more desirable choice - particularly the 410 does not have the vent system that the 411 series has. The existing air vents in a 410 are almost non-existant, or woefully inadequate to say the very least (located on the timber paneling at the bottom of the windscreen and one sitting under the dash on top of the transmission tunnel). Euphemism for suffocation!

[Sam410]

Sorry I didn't see this until now.

As David says I have factory AC in my 1969 410. (Also factory electric windows and door armrests.) The car is away being rewired at the moment but you can see a couple of overview pictures of the installation here:

https://www.classicandsportscar.com/...tionary-rebels

When the car is back (next month I hope) I can take some more detailed pictures and update the thread.

The hazard warning switch has not been moved from the usual location and can still be operated even if it can't be seen!

Rather than move the footwell vent lever, my car has separate levers for driver and passenger vents, one on each side.

Overall the AC works very well, and is especially good at refrigerating the driver's left knee. Ventilation to the rear seats is improved with the back widows open. It does however raise the engine temperature by as much as 10º or more when cruising, and if stuck in traffic the cooling system struggles to cope with the AC on top of its regular duties. I believe it is wired to run the fans constantly when the AC is on.

[David C]

Further investigation regarding fitting air conditioning to a 410 has made me think about the current draw that this adds - around 15 Amps. While an uprated alternator will easily provide the extra current, the ammeter and its original wiring were not designed with this load in mind.

Conversion to LED headlamps should lessen the load enough to prevent this becoming a problem. Otherwise I suggest wiring the air conditioning so that it disables the heated rear screen when in use. It is unlikely that both would be needed at the same time.

[Sam410]

I find AC a very useful aid to demisting, so don't discount using both together. My rear screen heater has never worked, so I don't have this problem. Maybe the new loom going in will fix that.

[David C]

Good point well made.

I think I will probably fit a newer alternator of at least 90 Amps with integral regulation. They look all but identical to the original. As I need to get the dashboard refurbished I will change from ammeter to voltmeter at the same time so that load in the wires to the dashboard can be reduced to a minimum.

I had a look at the 411 wiring diagram to see how Bristol changed the wiring as more toys were added and current consumption increased. An interesting anomaly to my understanding is that the 411 engine fans are fed directly from the battery if controlled by the Otter thermostat but through the ignition switch in manual override. Unless anyone can give me a good reason I think I will keep that sort of load away from the ignition switch.

[Roger Morrall]

Originally Posted by David C

I had a look at the 411 wiring diagram to see how Bristol changed the wiring as more toys were added and current consumption increased. An interesting anomaly to my understanding is that the 411 engine fans are fed directly from the battery if controlled by the Otter thermostat but through the ignition switch in manual override.

Seems to me to be unlikely, the comparatively unsophisticated wiring-wise 410 already had a relay mounted under the bonnet that had parallel trigger inputs from the otter switch and the over-ride switch and I believe the (later?) 411 wiring and fusing arrangements were further improved. So the load isn’t actually taken directly by either the otter switch or the ignition switch

Originally Posted by David C

Unless anyone can give me a good reason I think I will keep that sort of load away from the ignition switch.

I alarmed myself considerably when I tested and added up all the other potential loads on the poor little ignition switch (the windscreen wiper stall current on a dry windscreen was particularly amazing) and rearranged things so that the ignition switch drove a very heavy duty relay (sometimes known as a contactor) to take those loads.