Can't find a condenser!!

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davidr
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Re: Can't find a condenser!!

Postby davidr » Tue Jan 27, 2015 8:29 am

The car is all back together now but I haven't taken it out to have the gas put back in because of all the salt on the roads at the moment. I'll take it back to its regular storage in my friends barn up the road and bring the Celebration back when the roads dry up.
I'm presently occupied in refurbishing a set of front seats from a friend's X308 Daimler.
The next job after that is to have the radiator re-cored in the Celebration.
Regards
David
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

davidr
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Re: Can't find a condenser!!

Postby davidr » Sun Jul 12, 2015 10:13 pm

I finally got round to re- gassing the car. Aircon was working, although the output wasn't that great it was doing a job.
Took it out again yesterday and it wasn't working again. I put a pressure guage on and there was no pressure - all the gas gone in a week!
I'm perplexed as the system was both pressure and vacuum tested before it was gassed up and was fine. I've looked at the car and there's no obvious signs of a leak. Any ideas? I'm getting a bit out of my comfort zone now! Is there a pressure relief valve or something that could be letting all the gas out?
Any thoughts much appreciated!
Regards
David
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: Can't find a condenser!!

Postby ptjs1 » Mon Jul 13, 2015 9:42 am

David,

Just a thought: If a pressure test didn't indicate a leak but the gas has now gone, perhaps the problem is a seal on one of the valves where the machine was connected?

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

Brakebuster
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Location: Gloucester UK

Re: Can't find a condenser!!

Postby Brakebuster » Mon Jul 13, 2015 9:49 am

there is a PRV on the back of the compressor, and as Paul says, the Schrader valves may be letting by , especially of you have the screw on r134a adaptors on there ?

a dye test should indicate any leaks under pressure ( mixed with Nitrogen )

BB
1989 5.3ltr V12 XJS Coupé FULLY RESTORED
2004 2.1V6 X-Type Saloon in platinum silver for the good wife
1994 3.2S XJ40 in Morocco Red with Doeskin interior

used to have
1999 4ltr Sovereign XJ8 in Seafrost

davidr
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Re: Can't find a condenser!!

Postby davidr » Sat Jul 18, 2015 10:24 pm

Put the car back on an aircon machine today and the gas is still in there - just not circulating very well. I'm now beginning to suspect the expansion valve.
Symptoms are that the aircon isn't that effective - it is working but I don't get a blast of cold air that I would expect. The compressor isn't cycling as it normally should. It is supposed to cycle in and out as the evaporator reaches freezing point and warms up again.
My theory is that the expansion valve isn't opening enough to let sufficient liquid refrigerant through to make the evaporator cold enough to approach freezing point so the thermostat doesn't register a temperature low enough to send a signal to switch out the compressor clutch.
The aircon machine shows that the the low and high pressure sides don't have as much difference in pressure as they should - specifically the low side pressure is much higher than it should be.
Does anyone out there have better knowledge of these things than I do and does my theory make sense?
Regards
David
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

Brakebuster
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Location: Gloucester UK

Re: Can't find a condenser!!

Postby Brakebuster » Sun Jul 19, 2015 8:23 am

If your using r134a then this is possible as the valve should really be replaced because of the different molecule size of the gas

BB
1989 5.3ltr V12 XJS Coupé FULLY RESTORED
2004 2.1V6 X-Type Saloon in platinum silver for the good wife
1994 3.2S XJ40 in Morocco Red with Doeskin interior

used to have
1999 4ltr Sovereign XJ8 in Seafrost

davidr
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Location: Salisbury, Wilts

Re: Can't find a condenser!!

Postby davidr » Sun Jul 19, 2015 10:10 am

Thanks BB. The expansion valve was changed as part of the conversion to R134a more than 10 years ago and is one calibrated for the new gas. Over the years I've renewed almost all of my aircon system. The compressor, expansion valve, condenser and all pipes have all been changed for new ones. The only original parts are those under the dash (ie evaporator, air box, fans and controllers).
The blend flaps are all working as I'd expect.

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poprivet
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Re: Can't find a condenser!!

Postby poprivet » Mon Jul 20, 2015 3:35 pm

I can't add any advice, but I know how you feel. :(

There seems to be so much conflicting advice on 'tinternet about air con, it can't be such a black art can it? Almost every new car these days has it. I do wish that the club could provide more technical advice about keeping these older systems running.
1988 3.6 XJ-S coupe
'Remember that the value of your investment can plummet as well as fall'

ptjs1
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Re: Can't find a condenser!!

Postby ptjs1 » Mon Jul 20, 2015 5:18 pm

David,

Sorry to hear of your continued problems. When you say that you you "put the car back on an aircon machine"; was that with an aircon specialist or do you own such a machine? Are you just assuming that a good quantity of gas is in there from the high and low pressure readings, or did you evacuate the system? From my limited knowledge, it doesn't take much gas in the system to show indicative pressure readings. I would have thought that a specialist who understands the XJS system would be able to concur, or otherwise, with your diagnosis of the expansion valve.

I don't know if it's any help but my XJS is going in next Wednesday as my aircon isn't blowing cold, 12 months after the aircon was last serviced and gassed. If you can describe all your symptoms of the pressures that you saw, whether the compressor is running, clutch engaging etc, then I'm happy to try and get an opinion from the Jaguar technician who's doing my car.


Pop,

I fully agree with your desire for the club to provide more technical advice on these sort of problems. Perhaps you could write to Graham. I feel it needs far more members to constantly moan at the club (as I do!) as to why our paid technical advisers are not supporting the Bulletin Board and providing a comprehensive online service in this day and age. It seems that only a volume of complaints from members will make the club eventually do something about it.

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

davidr
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Re: Can't find a condenser!!

Postby davidr » Tue Jul 21, 2015 9:29 am

Thanks Paul,
I had the system evacuated, vacuumed and re-filled. We took as much out as we put back in which is how I know that none had escaped.
I'm afraid I don't have an aircon machine. I had it done by someone who does but isn't an expert in the diagnosis of these things. My observations are
1. The air coming out is cool but not very cold
2. The high and low side pressures were quite similar, specifically the low side was high
3. We put 1100grams of gas in the system
4. There is foaming at the sight glass
5. The clutch does engage and the compressor must be working otherwise we wouldn't have the pressures we saw
6. The compressor doesn't cycle in and out - it appears to be permanently engaged
7. I have not tested the evaporator thermostat
8. Blend flaps etc appear to be working normally
9. The pipe leading back to the compressor from the evaporator does get cold enough for condensation to form on it
My main concerns are that the system does work but not really well, the pressures appear to be high and the compressor does not cycle in and out as it should.
It may be that a combination of an older generation system and conversion to R134a (which is known to be less effective than the original R12) may be a lot of what I'm perceiving as underperformance compared to a modern car.

davidr
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Re: Can't find a condenser!!

Postby davidr » Tue Jul 21, 2015 9:39 am

Paul and Pop - agree with you both about the paid technical advisers. It does make you wonder why we rely on each other for knowledge on this forum when there is technical expertise available to the club.
I guess you could make the argument that we could contact the technical advisers directly with our questions and my experience would be that their answers will be both prompt and helpful. However, that doesn't help anyone else does it?
It would be much better if the technical advisers were active on the forums and then the library of knowledge available to all would be much greater.
There may be an argument that this would need more time from them but there must also be an element of repetition in what they do now and in theory, they shouldn't have to answer the same question twice.
Graham - James - any thoughts?

ptjs1
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Re: Can't find a condenser!!

Postby ptjs1 » Wed Jul 22, 2015 11:25 am

David,

I'll give all the info to the Jaguar technician next Wed and get his thoughts. Just one comment: AFAIK, I think your compressor IS supposed to run all the time. When Jaguar introduced a fuel cooler driven by the aircon, they presumed that owners would run the aircon continuously. When the convertible was introduced, they realised that convertible owners might not use the aircon all the time, so they made a modification in 1989 for the compressor in the convertible to run continuously to provide the fuel cooling. I don't know if that is true in all markets but I've definitely seen a US publication from 1989 which explained the modification.

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

davidr
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Location: Salisbury, Wilts

Re: Can't find a condenser!!

Postby davidr » Wed Jul 22, 2015 6:48 pm

Paul - interesting comments about the compressor running continuously. If it does, how does it prevent the evaporator from freezing and icing up?

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BigCatXJS
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Re: Can't find a condenser!!

Postby BigCatXJS » Thu Jul 23, 2015 9:57 am

Mine only runs when the Delanaire III unit is switched-on (low, normal or high). My temp is set to 70 (F) so will blow a gale with ice cold air if its hot outside OR push warm air to the footwells if its cold outside (subject to a warm engine - doesn't take long in a V12!). I *think* it runs even when supplying warm air as it takes the moisture out of the air. I only notice this behaviour as the engine revs drop at tick-over when the compressor kicks in. I understand that this should not really happen as there is a valve that is meant to actuate when the compressor kicks-in to supply more fuel to off-set the load of the compressor. Hopefully, others more informed than me can clarify the expected behaviour of the compressor and also if I have a faulty valve (without thread derailing).

Cheers, Rich
1989 Jaguar XJ-S V12 HE 5-speed manual
1994 Jaguar XJ40 Sovereign
2007 Mercedes CLK350 AMG Convertible
2010 BMW E92 3 Series Coupe heavy oil burner

Past Masters:
1996 Daimler Six LWB
2004 Volvo S60 D5 (RICA 210bhp)
1985 E28 BMW M535

ptjs1
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Location: Kent

Re: Can't find a condenser!!

Postby ptjs1 » Thu Jul 23, 2015 12:10 pm

David,

I'm not sure how it works but here's the pages from the brochure which introduced the Convertible.

Paul
Attachments
Aircon and Fuel Cooler 2.jpg
Aircon and Fuel Cooler 1.jpg
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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