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MG ZR ZS ZT Technical - Air Con on ZT260 all fixed

What a major job that turned out to be !

Rog wants a report on this subject but I can tell you it is a bigger job than meets the eye. You can see the pump, so it can be that difficult...think again!

At least I didnt have to take the engine or dash out to finish the project though!

SO warning to everyone out there in ZT260 world.
press the ECON switch when the weather outside is less than say 18 degrees you dont need the pump on and the ECON switch turns off the compressor

Get Mustang parts from USA, they arrive pretty quickly and other than hideous frieght charges and Gordon Brown ripping you off they come in much less expensive than UK sourced parts. It must be very inexpensive running a 'stang in USA


I'm lazy - and I tend to leave the climate control on the whole time, what ever the weather. But not had a problem with either the KV6 engined 75 or the CDTi ZTT - is this air con problem unique to the V8? I gather it's system is somewhat different to the ones fitted to other R75 derivatives?

BTW - when are you going to start importing cheap Mustang tuning parts Neil?

The Darkside calleth! ;o)
Rob Bell

you should really have the system off during cold weather.

The V8 seems to have a few probs with the Mustang Air Con, but with cheap US parts it wasnt a nigtmare project, in hindsight

cheap tuning parts exist on fleabay USA and some of the articles are very inexpensive, one of the cheapest being the plenum spacer. You can get 1/2 inch or 1 inch. I thnk I might experiment when I am sure that the project wont involve botching up anything. Also you can get bigger throttle bodies without changing the OEM plenum, which means of course that you keep the horsey logo on top of your engine. This is the only reason why I wouldnt buy the Accufab shiney plenum.

How much clearance have you got between the plenum and the underside of the bonnet?

I thought that part of the reason why MG Rover fitted the 2 valve push-rod V8 was because of clearance issues?

But I reckon that there is a lot of mileage in raiding the US parts bin - MG Rover barely scratched the surface...
Rob Bell


I have found some parts on the darkside

I have been under the bonnet already to see if they will fit.


Looking forward to hearing what is to emerge from the Surrey labs in due course then Neil! :o)
Rob Bell

oh oh
Fleabay purchases!

Neil, what problem did you have with your Aircon? Did the compressor get too hot and burn out the clutch and pulley bearing? What did you do to fix it?

No Martyn. the compressor seized solid. examination of the compressor proved, there wasnt much oil in it and the internals of the compressor had ground to little bits of swarf. quite a story I will write it up for the club


Oil leaked out, or inadequately filled from time of manufacture?
Rob Bell

plenty of pressure in system! so what's your guess then?

It's a pain to check the oil too. It involves degassing the system, and then taking the compressor off and physically measuring the oil that comes out when you tip it out!. Total cost of just checking A/C oil 85 plus 25 for the oil if it needs more.

Would have been a warranty item if such a thing still existed. Trident of course have left me out to dry on this. Options were either buy blinking expensive new warranty from them on top of the one the car had when I bought it. Or "run the gauntlet and get the spanners out" cover. So far repairs STILL havent reached the costs of the warranty! Trident lost the plot here.

Yes I know they lost a load of money when MGR went pop, but if they want me, or my family, or any of my mates to buy a car from them (Honda) in the future they should have cut a deal for me. Some dealerships are halving their workshop charges.

Did my own full service whilst at it, best idea when the air filter is stuffed right behind the bumper. No point in dealer service as there is no warranty to protect.

Neil I have a ZT 260 that I am working on now and the compressor packed up on it. When I first diagnosed it the pulley bearing had completely burned out and all the field windings in the clutch too. I had a new compressor made up by a specialist company and it worked for a while and 2 months later the owner came back and his aircon did not work again. This time the compressor bearings were ok but the gas leaked out of the compressor instead. Luckily we had another 260 arrived in our yard ready to go on sale so I swapped the compressor of it. While I had the pipes off I blew through them to make sure the system was not blocked and it seemed ok. Now after 2months again the bearing has burned out but the aircon still works. Obviously the customer and myself are getting a little cheesed off because I just cannot see anything wrong.
I have litterally stripped the whole system washed it out and I am putting a new filter unit in the condenser I just hope now it will be ok, oh and it is having another compressor on it.
I do hope your does not do this, all I can say is the filter in the condeser was rather dirty but air seemed to pass through it ok.

I got the compressor from USA cost $270 inc freight but Gordon brown charged DHL 40 for the pleasure of importing it. And I thought we had free trade in this country!

nevertheless it was a straight swap and came complete pulley, clutch, compressor all in unit. I hope it does hold together. The last one was utterly mullahed! internals all mashed, clutch bearing all falling to pieces totally seized solid

If the dryer was dirty it means that there is no end of muck in the system. I was lucky enough to have only the tiniest of black spots, about the size of a fag burn on the dryer bag, probably due to the sudden seizure of the compressor there may not have been enough time for the swarf to work its way around the whole system. The filter was just a little blackened, I cleaned it up anyway.

It isn't anything clever this system just a mix of Mustang compressor plus R75 rad, so we shuld be able to get to the bottom of it.


One would presume that the Mustang compressor is usually bullet proof - or are there hundreds of irrate Ford owners in the states complaining about duff air con?

If the unit is usually unburstable, it points to a problem associated with its installation in the R75 based platform...

Is it overheating?
Rob Bell

Not totally convinced, it could be overheating but I saw no signs of overheating/burning more a lack of lubricant.

Just in case solutions. only use A/C when needed in summer (ECON mode disconnects the compressor), and fit an underdrive kit. Both have the additional benefit of increasing performance however small that might be = worthwhile


And won't start
It's only the battery (again) but it's really annoying! GRRRRRRRR!

Solar charger for when parked for long periods Neil?

Air conditioning - so you are putting this down to a one-off problem of under-filled compressor gearbox?
Rob Bell

It's not LONG periods Rob! a couple of weeks and that's it, recently it's been just a few days and ...phut! so the battery charger is out there in the boot for a couple of days. I wonder if it is possible to fit a really MASSIVE battery to these cars?

Gubbebil Volvo 244 1982 car parked in a snowdrift over Christmas in Sweden minus 17 degress started first go after 4 weeks.

There is so much to be said about the positive aspects of Bangernomics!

Air con, I suspect not enought oil was put in it when it was new, or there was some sort of dirt in there. The system isnt that complicated (FORD) and works ok in a Mustang. Maybe it is a little bit hotter as an application, but I saw no evidence of overheating.

Underdrive kit mate, slow everything down.

Shouldn't be flattening its battery that quickly Neil. Is there a discharge (light remaining on) while the car is parked?

Or is the battery cream-crackered after being flattened a couple of times whilst in the Heathrow long-term car park?

Monster battery, mounted in the boot, may aid weight distribution ;o)
Rob Bell

It's its second battery from new

just celebrated a shiite day by listening to the tracks on

brilliant band!
whole album lasts about 4 minutes

Must have been a challenging morning in the recording studio then ;o)
Rob Bell


Does the car have an after market security system. If so it is a possible cause of battery drain. Roger Parker had problems with a badly fitted security system that the insurers had insisted upon.

When the car is switched off disconnect one of the battery leads and put a volt meter across the gap. This should tell you if there is a problem. I think Paul Hunt once wrote that a reading of 2v is a alternator diode problem. If you have a drain you can go through the fuse box removing fuses untill you find the problem.

From the wiring diagram you will be able to spot items wired from the always hot via a line fuse. You will not have been able to isolate them at the fuse box.

It will be something simple.

David Witham

David thanks for this.

I dont have an aftermarket alarm Halifax Insurance were by far the most sensible offer I had for this Gp 19 car.

I will take it up with Rog though

This thread was discussed between 13/06/2006 and 21/06/2006

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