Yes, it is very involved. But no, it's not that complicated. However, if you are not totally
confident with your skills as a mechanic (ie. can recognise bolt head sizes from 6 paces ..) then I
would not recommend you take this job on. It can be very expensive if it goes wrong ..
But enough scare mongering, if you're still reading then you are obviously up for it.
As the sticker says 'CAUTION: improper service methods may cause injury'. The first thing you will need to do is find a donor car with all the air conditioning parts that you need. Ideally the whole car that you can get next to yours while you swap everything over. There are lots of cheap spares or repair early Sterlings in the UK now, and I was fortunate enough to pick up one from David Jones from the Rover 800 mailing list (go here to join).
Ideally you should find a car with the AC system still under pressure, and even better known to have been working recently. Of course this adds the problem of getting the refrigerant removed, but there are plenty of mobile AC specialists around who will do it quite cheaply. When they remove the refrigerant ask them how much was in there. If it's the right amount matching the sticker (newer systems using R134 may have a different amount to that shown on the sticker above) then the system has not been leaking at all, good news.
OK, once the refrigerant has all been removed you can start swapping the parts over from one car to the other. We'll deal with this in two sections - i) dash and interior items, ii) engine bay items. Before you continue though it's worth a quick read about aircon systems, primarily concerning the risks of damage when they are exposed to moisture. This is a pretty handy site for background info, though does go a bit over the top sometimes. Basically you have to be quite careful and seal up all of the pipes once you remove them. The most critical part where moisture is concerned is the drier, though I would recommend fitting a new one anyway when fitting the system to your car. If it has a known history then you could use it, as long as you remove it and airtight seal it straight away. Let the air conditioning engineer who recharges your system fit it, as any moisture in there can make it totally ineffective and cause acid build-up as the damp reacts with the gas. This can wreck the whole system in no time at all. Other things to bear in mind are that all O-rings are supposed to be replaced whenever pipes are split, and that the amount of oil in the system is quite critical - so be careful not to lose any and try to estimate how much is lost if you do drop some (there's about 4oz in total I think in an R12 system, which is something like 50cc or so).
For those who are interested I spent new years day fitting the parts of the air conditioning which sit behind the dash (largely due the heater matrix failing and covering the floor in hot water). This lot consists of three main parts, the fan motor assembly, the evaporator and the heater box. The fan motor is different to the non A/C cars as is the heater unit so the whole lot has to be replaced! also needed is the piece of ducting that sits under the heater unit and leads into the ducting running under the center console. The controls on the dash will also be needed along with the wiring. The other thing to watch for is on the non AC cars there is a multiplug with about 8 wires running down to the blower unit, on the AC cars there are only two wires however if you cut this out of the doner car and attach the wires to those of the same colour on the multiplug all is well! also remember to take the wiring that runs accross the front of the ac assembly and the one that runs from under the heater box to the servo motors. You will also need the condensation drain pipe that sits under the condenser (this is like a big grommet with a rubber pipe through it). The AC controls themselves have two multiplugs, one to the AC loom and the other to the main loom, this is already there fortunately. What I would say to anyone comtemplating doing this If at all posible try to have the dead sterling doner car next to yours while doing it as there are a lot of non obvious silly little differences that will have you pulling hair out!
Perfect. Thanks Stewart, I just used this and the interior stuff all went in a treat. Removing the
whole dash assembly is not as bad as it looks, and since I put mine back I've lost all of the squeaks too :) Just one other thing that I would add is that it's worth extending the evaporator drain tube with some hosepipe as the normal length drips straight onto one of the crossmembers at the back of the engine. The controls are much nicer to use than the non-AC ones too.
The pipes should be fairly obvious, the brackets all come off the donor car and should go in holes in your car easily enough. The pipes behind the battery (take it out) and under the fusebox are a little fiddly, but with some care can be fitted quite neatly. If any of the pipes are damaged then replace them with new ones, it's not worth messing with risky connections in the refrigerant lines. The drier and housing can be fitted behind the RH headlight, which is all a little tight but if you remove the cruise actuator and swing the power steering top up tank out of the way you should be able to do it OK. As previously mentioned the drier is a little critical, so unless you are confident with it (and you've carefully sealed it) then it's worth just replacing it. You can get them for £35-£65 depending on the fittings it has, most early cars are the more expensive type. Near the drier is a pipe with 2 switches screwed into it, the fatter one is the dual pressure switch which we will use for the compressor wiring and the other is the high pressure switch (usually used to control the condensor fan speed).
Now if you refit the radiator and the condensor in front of it then you should be able to connect up all of the pipes ready to be charged. Obviously there's no wiring yet, checkout the wiring from the manual. Here's how I wired mine in (again from 800 list archive) -
The final part of the compressor wiring was quite simple once I found the connector (C16 - under the power steering resevoir). There are 3 wires running from the main loom to that connector which do not come out of the other side, it's possible that if you have a 2.7 donor car you could simply swap the whole extension part of that loom over. I couldn't use the wiring from the 2.5 because the cruise control is different. Anyway I wired the following -
That should take care of the compressor, and if you turn it on without the engine running it should still try and engage the compressor. If you look carefully at the circuit diagrams you will see that the fans are wired in a very complex arrangement of slow and fast, double and single running. That looked far too complicated to me, so I wired the condensor fan through a relay to the alternator charge circuit (I had that already from my towing socket wiring) and it now runs once the engine is started. The main fan is still wired normally and only comes on once the radiator is warm.
OK, that should just leave fitting the belt to the correct tension (pretty tight) and taking it to a good AC shop to get it tested and charged. Best of luck with that, it can be as little as £100 to test and charge (R12 is still only £30 a kilo, despite what people might tell you it is readily available too). I ended up having a hose re-made, bought a new drier anyway and had ultra-violet dye added too. Total bill including labour was just over £250, but worth every penny.
More pictures to follow here too ...
Simon, Mar 2000.