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Air conditioning

Neil Potter

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This might turn out to be a protracted blog, but here's the story so far...

The air con on the car has not worked in my ownership, which is the only mechanical bit which doesn't work. The receipts file shows a new condenser was fitted in 1997, and was converted to R134a at the same time, but that's a long time ago. I had a specialist look at it, and was told that the system was holding a vacuum (slightly surprisingly) and the electric part of it was working fine, but the compressor was duff and needed to be replaced.

[b]Part 1 - compressor replacement[/b]

[i]Sourcing[/i]

I managed to source a second hand Sanden SD508 compressor from Ebay, for a bargainous £45. It came off a Saab 900 apparently. The compressor has an interchangeable backplate, where the hoses go in, and I was aware that the Sanden I had bought had two different hose ports, so the backplate from my old compressor would need to be recycled onto the new compressor.

That necessitated new gaskets. I managed to get a gasket set from a company in Australia, but it took a bit of research. I think if you are able to buy the backplate with the flanged connections (as required to fit our hoses) from a Sanden dealer you may well get the required gasket included.

IMPORTANT... You should note that the compressor actually has two different gaskets, one either side of the reed valve plate which sits between the backplate and the compressor body. If, when you are trying to separate the backplate from the body, you end up separating the backplate and reed valve plate from the body (as I did) you'll need both gaskets. If you do ever have to do this job, take great care to keep the valve plate attached to the body as gasket removal on these compressors is an ENORMOUS pain in the bottom.

[i]Removal[/i]

Remove the hoses before you remove the compressor, and you'll probably need lots of WD40 to free them off. My system was empty, but if yours isn't I think it's a bit illegal, and a bit dangerous, to remove the hoses and release the gas.

Actually getting to the compressor isn't too hard, but I had already removed my alternator for rebuild. There are two bolts fairly easy to get to from the top, then another two you can get at below. You need to remove the belt tensioner to get at the final bolt.

[i]Fun with gaskets[/i]

If you need to replace the backplate, once you've got the compressor off, you will put it in a vice and start hammering away to get the backplate off. Use a chisel or something, carefully, to try and prise it. It'll be stuck like concrete.

When you've got it off, you may well be faced with lots of old, gloopy, brown oil. Drain it out of the compressor body via the drain plug, and clean up the face of the reed valve plate before trying to get rid of the gasket material.

Gasket scrapers were next to useless in this task. I ended up using a dremel sanding disk, got through about 6 discs for each surface. A very time consuming job, and not ideal as you'll remove some of the metal from the surface. I then cleaned up the surfaces with some fine wet and dry paper. If you've unintentionally split the reed valve plate from the body, you'll have up to four sufaces to clean up before reassembly...

Use some PAG46 oil to lubricate the gaskets and surfaces before you reassemble.

When bolting up the backplate, check the interweb for the useful Sanden SD series service guide PDF. This specifies the torque settings on the bolts, which are 14 ft lbs intially, then 24-27 ft lbs for final.

[i]More fun, this time with pulleys[/i]

Around about this point, I noticed that the pulley on the new compressor was different to the old one, to the extent it wouldn't work in the Esprit. The Esprit one has two grooves, whereas the Saab one has one groove at a different distance from the compressor body.

This isn't too bad to sort. You'll have to:

- use some bolts in the 3 threaded holes on the clutch plate, in order to hold the pulley steady and allow you to remove the retaining nut
- prise off the clutch plate (I used a small bearing puller on the bolts I'd put into the threaded holes)
- use circlip pliers to remove two circlips holding the pulley in place against the bearing (one "outty" around the compressor shaft and one "inny" against the pulley on top of the bearing outer race)
- use a largish bearing puller to remove the pulley and the bearing

I swapped the bearing from the Saab pulley to the Lotus one as it felt a lot smoother.

Then do the reverse of all this to get it back together again!

I think it's probably wise to install oil in your "new" compressor before reinstall, as the drain/filler hole is at 90 degrees to the vertical on the Esprit install. As I don't know the right oil I should be using, I'm leaving that to my specialist to install in situ.

One Esprit-ready compressor, ready for action.

Fitting it back in the car is pretty straightforward, but it probably helps to have someone hold it while you start securing bolts.


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