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AIr conditioner won't engage 88 Turbo - Engine/Ancilliaries - The Lotus Forums - Lotus Community Partner #ForTheOwners Jump to content


AIr conditioner won't engage 88 Turbo


Carl J

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I had my A/C checked while my vacuum pump was being replaced. They said the pressure was all good. It was never warm enough to test it but it was 30C yesterday so I took it for a drive and no cool air could be felt. On a good side note the engine ran well with no over heat issues so I know my fans are working. 

Any ideas where to start?

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Hi Carl,

Not an expert on the Esprit A/C, but it works the same as any other car so... what I learned on my daily runner while taking its A/C apart, along with the practical advice I was given by an actual A/C specialist/independent, might still be helpful.

 

If the system is checked and found to be charged, then at least we know that there is enough refrigerant left in the system and that it is not leaking.. otherwise the refrigerant would have disappeared long ago. So that also means that the fragile/exposed/prone to failure condenser is not leaking either, which is good news for you, as would be expensive and labor intensive to replace.

So next move is to make sure the compressor is actually running : with the engine idling, switch the A/C on : you should feel/hear a slight and sudden drop in engine RPM (then followed immediately by an increase, ECU is now compensating), due to the extra load the compressor puts on to the engine. This will rule out any electrical problem that could cause the compressor not to run: a dodgy low-pressure cut-out switch for example.

If the compressor is running and we have enough refrigerant in the circuit, and still no cold or not enough cold... then the specialist told me it is usually due to :

- The expansion valve malfunctioning (sticking, or seized altogether...) needs replacing. They don't last forever, especially as they typically are not used regularly enough to be kept healthy, just like any mechanical device...

- The dryer that's "full" (of water) : it's a consumable, needs replacing. Its role is to store/remove moisture from the system... once it's full, it's full, nothing to do but replace it with a brand new one, and make sure you wait 'til the last second before removing its plugs/seals and fitting it to the system that's otherwise already sealed everywhere else... otherwise you just make the drier suck the ambient moisture, reducing its life expectancy stupidly !

- Lastly... and after you have fixed the two above issues, you may be unlucky and have a defective/worn out compressor. I guess this could be tested by checking the high-pressure side of the compressor to make sure it's strong enough.

 

So I guess my advice would be :

1) Rule out any electrical problem (in case the compressor does not run), because this you can do yourself and for no money.

2) If compressor does run, then not much else you can do yourself at this point, so take it to an A/C specialist, an independent (even it that can take some searching to find one), not  some crappy car center that knows shit but will charge you anyway. You should get much better service from a real specialist. He will be able to check the health of the compressor, then if its OK, you sorta know that the drier and valve need replacing. It's not worse being cheap and replacing only one or the other. Just replace both at the same time and you will be set for a long time.

Otherwise if you are likely not to get optimal performance and will need replace the other component soon after... and pay again to recharge the system yet again ! Not worth it... For efficiency and peace of mind, it's really highly advisable to replace both the drier and valve at the same time. Of course that's assuming the valve is still available new... no idea ! :-/

Drier should not be a problem I think, even if the original is not available, it should be possible to fit a different model, most of them share the same basic mechanical design/shape.

 

The service manual ( 'PD' section)  does give plenty of information on the A/C.

Hope this gives you some pointers, until the more experts out here come to correct me ! ;-)

 

 

Edited by troutrou
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Thanks. I was thinking it may be the A/C relay. When I turn on the cold I don't hear the compressor engage at all. No engine lag either. Can I swap out another relay to see it that will start the compressor?

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OK, so looks like you might be lucky and the A/C is fine and it's just an electrical problem ! Time to get your multimeter out then, and go poking around, armed with the electrical diagrams ! ;-)

Can't help you with details as I don't even have an Esprit, but it's just basic electrical troubleshooting, so should not be too difficult/long to diagnose, I would think !

... of course accessibility might get in the way of concerned electrical components, I wouldn't know, short of a car.

Others will be able to help I am sure.

But if you already suspect a relay or whatever, and have a spare one at hand, then yeah doesn't hurt to swap them. But in the general sense, it's best to first properly troubleshoot the problem so as to exactly know what's wrong ! ;-) Swapping parts blindly is not exactly troubleshooting... and can cost time and money, if you swap parts that didn't need to. Maybe it's just the wiring needing refreshing, and there are actually no faulty parts anywhere... again you can't know until you get your multimeter and start troubleshooting the thing methodically ! ;-)

Edited by troutrou
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If you don't already have it, here is a copy of the electrical diagram for the A/C (and heating and cooling) circuit.

Just start at the beginning : from the compressor/clutch then move upstream progressively, one step at time, methodically.

So first, engine stopped, run a wire from the positive terminal of the battery , and feed the clutch directly, to see/hear if it engages or not !

If it does, then the problem is upstream, so start up the engine and turn the A/C on and poke around 'til you find the faulty part ! ;-)

Engine running means be careful where you put your hands and tools ! ;-)

Have fun ! Shouldn't take you too long, depending on your experience with electrical troubleshooting !

One thing that troubles me though, in this diagram, is the DIODE 'D6' ! polarized as it is, with 12V on it's cathode and ground on the anode, I don't see how current could ever flow through the coil of the clutch ?! Hmm.... I must be misinterpreting that diagram... if anyone could shed some light...

 

P7090036.JPG

Edited by troutrou
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BTW, something totally unrelated... your avatar says you have an '88 SE ?!  Either it's a typo, or you managed to lay your hands on an early prototype of some sort ?!

Thought the SE didn't hit the market until mid-1989 from memory...

Edited by troutrou
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I have one of the limited edition 1988 models. #32 of 88. The paperwork when it was imported in the US back in 1989 has it listed as a SE. I had always wondered if that was correct. The silver number plate says limited edition. 

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Sounds like it's a regular 88 Turbo, not an SE.. but that is easy enough to figure out, just send a few pics of the car, exterior, interior and engine bay ! ;-)

If it's an SE you will find the big red intercooler sitting on the engine, to start with ! :-)

 

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I updated my profile. Now if I can only get my AC working. It's freakin hot here for the next few weeks. I hate electrical. The compressor did engage when my service guy applied power directly to the unit so he could test the pressure. I checked all the fuses and they are all good. The fans do engage when I turn on the AC. But no compressor engage. 

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OK, so from you just said, looks like the compressor is good (gives enough pressure), and the clutch works too, and the fans work as well.

So basically all you need to figure out is why the clutch is not being powered... so again, get your multimeter out, and print the diagram, and start troubleshooting ! ;-) Sorry but not much else I can tell you... I can't do it for you... you have the car not me ;-)

Yeah electrical problems are a pain, but the more you do it the easier it becomes... and the hot weather is supposed to motivate you, I would think ! ;-)

 

Looking more closely at the diagram, I understand what's going on with the reversed biased D6 diode... 12V is not supposed to come from the rad relay at all ! So no point swapping it. Instead, power to the clutch comes from the low pressure cut pout switch, makes sens, so check that. As I already said, just work your way backward until you find where in the circuit the 12V disappears !

 

Edited by troutrou
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