Air con not very cool

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davidr

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Air con not very cool

Postby davidr » Tue Jul 31, 2012 10:23 pm

The air-con on my 1989 V12 is not very effective. The compressor appears to be working in that its inlet pipe is cold and the outlet hot.
I have moified the auxiliary fan so it comes on when the compressor clutch comes on and fitted an additional pusher fan ahead of the condenser so there should be plenty of cooling airflow through the condenser.
I replaced the cooling rad recently so I know that there's nothing blocking the airflow and that the sealing foams etc are all new and in place.
The system has been converted to the later 134a gas and I think that there's enough gas in the system.
As far as I can see, the controls are working as they should in that it attempts to blow hot or cold air out of the appropriate vents.
I have noticed that the compressor doesn't cycle as it should but stays permanently. Could it be that system isn't managing to get the evaporator cold enough to cycle the compressor off?
Has anybody got any ideas?
XJS FORUM COORDINATOR
1996 XJS Celebration Conv. (shown on the JEC stand at NEC Nov 2015)
2001 XKR Convertible

Previously enjoyed!
1989 XJ-S V12 Coupe. 2006 XJ TDVi Sovereign. 1995 XJ6 3.2. 2013 XF 2.2d. 2009 X Type 2.0d Sovereign estate

PaulE
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Re: Air con not very cool

Postby PaulE » Wed Aug 01, 2012 12:23 am

Apparently 134A is not as efficient as the previous gas so you will have some lessening of effect, but before you look at anything expensive it might be a good idea to get your gas extracted and weighed and check whether the system is full. An efficient system still loses about 5% a year I was told.

Strange though that Jaguar aircon seem to be so easily upset when other cars such as my 10 year old SAAB just carry on with instant ice - cold blasts whenever needed.
1994 Coupe AJ6 engine

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poprivet

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Re: Air con not very cool

Postby poprivet » Wed Aug 01, 2012 7:50 am

David, are you saying that it has never worked correctly, or it used to but now doesn't.

If the latter, it could be just low on gas assuming that the blowers and flaps are all working correctly. The system will lose some even if there are no leaks due to hoses and seals. I have to top up the Citroen every 2 or 3 years to restore full working chilliness.

Obviously an A/C specialist will drain and refill and is the best but most expensive option, personally I use EZ Chill which you can get from Halfords. You will need the pressure gauge/adaptor which isn't too expensive (from Halfords as well). If you go to :

http://www.interdynamics.co.uk/retail/product.php?id=71

it explains it better then I can.
1988 3.6 XJ-S coupe
'Remember that the value of your investment can plummet as well as fall'

davidr

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Re: Air con not very cool

Postby davidr » Wed Aug 01, 2012 8:50 am

Thanks guys or your input.
The system was refilled last year as I changed the hoses (the old ones had gone shiny due to oil coming through them so they'd gone porous).
I know that R134a isn't as efficient as the original R12 but it shouldn't be this bad! When I converted it I did put in a replacement expansion valve that is calibrated for the new gas.
Pop - I do have one of the kits that you mention. The gauge shows that the system is in the right pressure zone (ie in the blue). It should cycle between the top and bottom of the blue sector on the dial as the system cycles in and out. Mine doesn't do this - just sits somewhere in the middle with the compressor clutch permanently engaged. I know the clutch is working OK because I can hear it engaging when I turn the ignition on. It also disengages when starting from cold.
Any more ideas?
XJS FORUM COORDINATOR
1996 XJS Celebration Conv. (shown on the JEC stand at NEC Nov 2015)
2001 XKR Convertible

Previously enjoyed!
1989 XJ-S V12 Coupe. 2006 XJ TDVi Sovereign. 1995 XJ6 3.2. 2013 XF 2.2d. 2009 X Type 2.0d Sovereign estate

ptjs1

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Re: Air con not very cool

Postby ptjs1 » Wed Aug 01, 2012 5:01 pm

davidr,

I'm no aircon expert but have just had mine serviced. It hadn't been running cold for some time, so I decided to get it sorted.

When it was connected to the system, the pressure gauges (which measure separately on the high and low pressure sides of the system) indicated broadly acceptable pressures. However, when the existing gas was evacuated, it proved that it was extremely low on the volume of gas. After being recharged and no leaks showing, it's now functioning correctly.

As the pressure is not necessarily an indication of the volume of gas in the system, I think you're only going to really know by getting the gas fully evacuated and recharged.

Good luck

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)

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ng4xjs
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Re: Air con not very cool

Postby ng4xjs » Thu Aug 02, 2012 8:43 pm

134a is fine. It works for me. My current XJS used it from new so I suppose it should. I converted my previous 1992 XJS, and the only concession I made was to change the receiver dryer unit. Was still working faultlesley (ice cold air) when I sold the car some four years later.

Nick


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