Plus 2 Air Conditioning Project - now complete!

[Chrispy]

I'm intrigued by the evaporator, for me that's the hardest part to fit, would you try to replace the heater unit?

Given how standard the Smiths heater is (Midget, Ford etc.) I'm surprised that no-one has produced an off the shelf replacement incorporating aircon.

Yep, have to completely remove the standard heaterbox to have any chance of fitting it, might loose a little bit of the glovebox too - it I haven?t had one installed for a long time anway.

[gus]

Mine is recirc only, I found little room for a way to plumb an external vent. One can open the windows if fresh air is desired.
With the unit in my car I reshaped the back left corner of the glovebox, hardly noticeable.

[gus]

Found where I posted some details:

lotuselan-plus2-f51/air-conditioning-t30738-15.html

[mikealdren]

Thanks for the link, I'd forgotten this thread.

[baileyman]

My old Plus 2, the pleasure of ownership of I am late in life trying to rekindle with an S2, has "factory" air, probably installed by a dealer, as the car lived in Louisiana, similar to Brisbane, but without the little green ants.

The compressor was a giant Briggs and Stratton, under dash passenger side evaporator, front of radiator condenser using the standard fan, and under dash controls. The compressor had to go, so as a young guy I swapped it for a Nippon Denso found at a garage sale, cobbling together a bracket or two for it to work. Nevertheless, the water pump eventually gave out, as feared due to side loading (I suppose), leading to a Bean modification.

The system on the worst days was always a bit unsatisfactory with either compressor. Eventually I pulled out the front bits and ran without, where the face level vents provided nearly the same pleasure. Perhaps also due to the AC inadequacy I had a fellow reupholster the front seats in fabric to breathe. I'm not sure I was happy with that either.

I keep thinking maybe I could have avoided water pump trouble with a two-belt crank pulley separately powering the compressor.

John

[2cams70]

I've been digging around and I've found that Mk1 Escort air conditioning system. Attached are pictures of the compressor mounting bracket to suit a crossflow engine. It seems to be quite a sturdy affair with a 4 bolt mounting system to the engine block. One attachment point is through the engine mounting. It does not look like it would fit a Lotus Twin Cam without modification to the front facing part and belt tensioner arrangement. It has a separate independent belt for the compressor running directly off the crankshaft pulley.
When my Lotus engine is at a stage where the head is bolted on I might try offering it up to the engine and seeing how it looks. May be useful as a source for ideas in any case.

[USA64]

Rather hefty piece! Sobering to see the factory's idea of the forces involved.

[Chrispy]

Thanks for the photos, certainly hefty! I wasn?t going to be going that heavy. I?ve got some guidance somewhere on belt forces in my old engineering books, I?ll run some numbers on it.

[gus]

I would say that compressor is too new a style for a 70's car.

Picking up that engine mount bolt is not a bad idea

I would think the concept is good for the twink, similar to where I hung mine, I put the alternator below so I could preserve the servos

[lotusfan]

I would say that compressor is too new a style for a 70's car.

Sanden compressors have certainly been around in UK since the late 1970's and looking at the Sanden website it says production of SD compressor started in 1970. Thus it could be a good choice.

[Chrispy]

OK! Finally an update

Here's a few comparison shots of the old heater and the new combined evaporator/heater assembly.

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Here it is sitting behind the dash. Please excuse my embarrassing mess of wiring Fits reasonably well and just enough room for the demister vents, and about 50mm clearance between the evaporator and the back of the dash.

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6

The originally supplied condenser from the Hilux didn't fit, the measurements in the book was only for the core and didn't include the end tanks. Ended up with a a couple of generic ones the AC shop lent me and I kept the biggest one I could fit. (the rough one was a mock up one only, shiny new one now in place). I bent up some basic brackets and attached them to the radiator mount. Also stuck on some foam to seal the rad to the condenser. I found a heavy duty 14" Davies Craig termofan which I previously used on a V8 converted 300ZX, if it can keep that cool it should do ok on this! I'll be using a trinary switch.

Installed a drier which I've mounted in front with just enough clearance for the bonnet to open and the headlight springs to clear. And if you're wondering why the condenser is wonky compared to the radiator it's the delicate balance between being level and matching the existing radiator I think the radiator is on the piss a bit to ensure the air comes out the filler.

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Mounted up the compressor as low as possible. Pretty close to the front crossmember and the side of the chassis. My alternator didn't have a hope of fitting without moving the servo which I didn't want to do. Ended up with a new little Denso alternator which said 40A on the add, but tested out at 52A which happens to be more than my old one! I'll put up a picture of the brackets once I have ground all my ugly welds back and give it a paint measured the electrical draw from the fan blower and the AC clutch - bit under 9A with everything on high.

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8

I'll keep plodding along and update as I go

[Chrispy]

Sorry for the wonky photos, they were correct on my computer

[mbell]

Thanks for the update and pictures. Very interesting and good to see that its very similar to what I have in mind.

Do you have the dimensions for the condenser you used?

Have you check your evaporator positioning for clearance on the glove box/under trim? My understanding is it just slightly too large to fit with out a couple of tweaks to the glove box or trim.

Are you or have you sealed up the original air intake for the heater?

[Chrispy]

I'll get some dimensions, but the core would be approximately 350mm x 450mm. The A/C shops said it would be suitable. Just a little less width than my standard wide style Stanpart radiator.

I have got a bit of ally sheet which I have bent some edges on to stiffen it up a bit. Will put a bit of sealing foam on it and screw it in over the old intake hole. I'm hanging the new evaporator off the existing heater box bobbins. Intent is to make everything completely reversable except for having to patch up some holes through the firewall.

Haven't checked the glovebox as yet. Flying back from work tonight and off to a Wedding in Melbourne, but should have some more info mid next week

[Chrispy]

Time for another update!

Sorry, didn't check the glovebox clearance The condenser according to the receipt is 18" x 14" x 7/8".

Here's the completed bracket for the compressor and alternator, not very pretty but it seems to work well so far. Tensioners aren't shown.

With the wiring being a complete dogs breakfast, I went with one of those universal wiring kits that hot rodders use. Nice tiny mini fuse type fusebox and plenty of circuits. Only thing I had to add was a heap of crimp connectors, earth cable, a few relays (for wipers and headlights) and loom wrap. Also needed a new turn indicator clicker as it was wired for two dash indicator lights rather than one. It even came with new headlight plugs, grommets and zip ties. Cables are labeled every 300mm making it easy too. Very happy with it.

Compared to the old mess

I've made a new dashboard, moved some of the locations just a touch to suit the new HVAC controls but not make it look too out of place. Once it's all good I've got some walnut burl veneer for it. It's very warped so it might be exciting!

Dash wired and evap unit installed behind the dash and ducting in. Very tight fit. If I was to do it again I would try and get another 10mm closer to the firewall somehow. I wanted to keep the unit as level as possible.

Took it out for a run to cars and coffee a few days ago too, no thrown belts and all the electrics are running well. As is pretty normal these days I had the only classic Lotus there Occasionally a baby Elan turns up. The new Evora GT430 was something special though!

I've now dropped the Lotus down at the AC shop to get piped and gassed up. Winter is a nice time of year for the shop as they don't have a lot of work on Still expecting a top of 22degC today