410 Air Conditioning

John Keighley · #1 (**permalink**) 04-10-23, 11:11 AM

Hi David,
Thank you - we did consider a different transmission but refurbished the existing one for the moment. I will try to get the photos of the A/C installation, There have been some modifications of the ventilation system necessary such as relocation of the air vent lever and hazard lights switch that both reside under the dash centre and on the transmission tunnel so that the unit can fit in. I have attempted to attach a photo of the A/C unit in situ to illustrate but I don't think it's working.
Attachment 1859

EDIT: Not sure what happened there John, but I have added the photo - see below. Kevin.

David C · #2 (**permalink**) 04-10-23, 12:23 PM

Please keep trying with the AC pictures. Where did you relocate the hazard switch? It looks as if there might be room to put it on the front of the gear selector cowl.

Kevin H · #3 (**permalink**) 04-10-23, 01:25 PM

Quote:

Originally Posted by AndrewA

Kevin who kindly looks after this forum will probably sort it out for you if you ask nicely!

I will indeed! John, please email the image to webmaster @bristolcars.info and I will get it uploaded for you.

Kevin

Kevin H · #4 (**permalink**) 04-10-23, 11:55 PM

I have added the missing photo of John's air conditioner to his post http://www.bristolcars.info/forums/8...html#post12982

David C · #5 (**permalink**) 05-10-23, 07:59 AM

Useful picture, thank you. It would be really handy to have a picture of where and how the A/C compressor is mounted on the engine if possible, please.

Thomas591 · #6 (**permalink**) 06-10-23, 09:53 AM

Quote:

Originally Posted by David C

Useful picture, thank you. It would be really handy to have a picture of where and how the A/C compressor is mounted on the engine if possible, please.

Here are some pictures from my Bristol factory installed AC system.

Regards
Thomas

John Keighley · #7 (**permalink**) 07-10-23, 10:30 AM

Quote:

Originally Posted by David C

Please keep trying with the AC pictures. Where did you relocate the hazard switch? It looks as if there might be room to put it on the front of the gear selector cowl.

Hi David,
I’ll eventually be able to post some photos but the problem is that the car is over 1000 km away so when able, I’ll get some pictures onto the forum. Sebastian Gross (Bristol specialist) is currently working out where to relocate both the hazard lights switch and the air vent selector as both of these have to be moved.

John Keighley · #8 (**permalink**) 07-10-23, 10:34 AM

Quote:

Originally Posted by David C

Thank you for that. Loving the exhaust manifolds. Who made or supplied those?

I'm still keen to see some pictures of aircon compressor mounted on 410 engine as this is very different from the 411.

Hi David, I know the alternator has to move to allow installation of the compressor but we haven’t reached that point yet. Hopefully soon I’ll have something to show.

David C · #9 (**permalink**) 07-10-23, 10:46 AM

You may not have to move the alternator. Sam Frost kindly sent me a link to pictures of his 410 that has a factory installed A/C system. This has the compressor mounted above the power steering pump and looks a much better proposition in a Bristol. His car is away at the moment but I'm hoping to have a good look at it when it returns. If I go ahead with the conversion I plan to make some similar brackets but for a smaller, lighter compressor.

If anyone else is interested maybe we should get a design together that can be easily reproduced for anyone following suit.

I am wondering whether to change the hidden under dashboard quadrant ventilation control for a push / pull that is a bit more accessible.

Kevin H · #10 (**permalink**) 07-10-23, 01:56 PM

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 · #11 (**permalink**) 12-10-23, 10:10 AM

Quote:

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 · #12 (**permalink**) 17-10-23, 01:31 PM

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 · #13 (**permalink**) 04-11-23, 08:06 PM

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 · #14 (**permalink**) 09-11-23, 05:40 PM

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 · #15 (**permalink**) 09-11-23, 08:34 PM

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 · #16 (**permalink**) 12-11-23, 04:17 PM

Quote:

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

Quote:

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.

David C · #17 (**permalink**) 12-11-23, 06:52 PM

I agree it's unlikely, but it doesn't necessarily mean it isn't so. My interpretation of the 411 wiring diagram on the BODA site is as stated. See attached and let me know if I have got it wrong.

It looks as though the thermostat switched relay is fed via a fuse from the battery while the manually switched relay is fed by an in line fuse powered through the ignition switch.

http://www.bristolcars.info/forums/a...1&d=1699814779

Sam410 · #18 (**permalink**) 12-11-23, 10:07 PM

I haven't checked the diagram or the car itself, but the 410 handbook does state that the fuse protects the "manual control switch for fans" and is controlled by the ignition switch, so certainly implies that there are two sources of power to the fans. Incidentally I believe that running the AC on my car will also switch on the fans regardless of engine temp.

David C · #19 (**permalink**) 12-11-23, 11:39 PM

To summarise:

The 410 has a single fan relay which is operated by the Otter bimetallic switch in the top of the radiator. According to the wiring diagram the manual switch passes full current and does not operate the relay. Both options, automatic and manual operation are fed from the ignition switch.

The 411 has two relays, one for automatic thermostatic control and another for manual override. The relay for automatic control is fed directly from the battery and the relay for manual control is fed from the ignition switch.

My feeling is that I would rather not have this much current flowing through the ignition switch. I have seen melted switches and wires on early V8s. It's much easier to prevent the smoke coming out than to get it back in.

The ammeter and wiring on the early V8s coped - just - with the original load but as we add more power hungry accessories it is important not to add more load to the ammeter or to the ignition switch. This is easily achieved with relays fed directly from the battery controlled by feeds supplied from the ignition switch but this will not show up on the ammeter. Much better to ditch the ammeter and replace with a voltmeter per 411 which will give a better overall idea of what is going on.

Roger Morrall · #20 (**permalink**) 13-11-23, 11:51 AM

Quote:

Originally Posted by David C

I agree it's unlikely, but it doesn't necessarily mean it isn't so. My interpretation of the 411 wiring diagram on the BODA site is as stated. See attached and let me know if I have got it wrong.

It looks as though the thermostat switched relay is fed via a fuse from the battery while the manually switched relay is fed by an in line fuse powered through the ignition switch.

http://www.bristolcars.info/forums/a...1&d=1699814779

My apologies, on checking the 410 wiring diagram I found my memory of the standard 410 arrangement to be faulty. You are absolutely right