Well contrary to the rest of the world, I guess, we in Los Angeles have had the coolest summer in the 62 years I've been alive to experience them. But upper 90's have finally come into the San Fernando Valley this week. I run my A/C every day as I'm always warm but besides the annoying few minutes of no cold air at first startup (which has been commonly reported), I find that if I'm at a red light or in very slow stop and go traffic, I lose cold air during that time, and it only returns once I maintain a steady speed where it will "freeze" you it's so effective. Considering I spend the better part of two hours a day in stop and go traffic, for much of that time the A/C is non-cooled air. If it were a matter of low freon, why would it work so well when traveling at even modestly low speeds? Is there a temperature sensor that shuts the compressor off to prevent overheating when the car isn't receiving cool air via the grill opening? Has anyone else experenced this or is it peculiar to my car?

 

My guess is you are a little low on freon. The more flow of air over the condenser enhances the cooling as the compressor moves the freon through the system. You need to put a set of gauges on the system to see what the pressures are and most likely you just need a shot of freon. Depending on outside temps at 90* you should see around 50 psi on the low port with the car idling. This would give you about 45-55* temps at your center AC outlets.

 

Sorry, don't have a direct answer, but, I don't experience the same issues with my '08. Sure, it's warm on start-up but then, so is my '09 Venza. After all, there is a lot of heat in the air ducts and the AC has to drop the cabin temps 30-40º in a short period of time. I've always felt the vehicle AC systems, when working as designed, are very efficient at what they do. Get a pencil gauge and check the center registers for drop.
It would not surprise me, if these per-snickety cars have some type of cut-off limiter when over heating is imminent. However, perhaps it's time to check the levels. There are a number of DIY kits for this.

 

Have you tried the recirc button?

 

Hi Ralph,
I always have it on recirculation as I don't want to have to recool hot outdoor air. I am going to have freon level check later this week and see if it's low.
Thanks,
Ted

 

Just an FYI . All modern cars have a delay compressor start so when you start the car and if it is in AUTO the fans turn on but the compressor doesn't . There is usually a 5-10 second delay where the fans blow warm air out of the ducts. When the compressor turns on then you'll start to get cold air as the freon circulates. Recirc position should be used on hot days for the first 5 minutes to minimize the warm outside air from coming into the cabin. I would not use it all the time as it dries up the inside air and could potentially freeze up the evaporator. A properly functioning system should work well under normal conditions with outside air passing over the evaporator. Any normal operating system should blow between 40*F-55*F temps out of the center duct during 90* outside temps. I find that I usually set the temp. to 72* on auto and leave it there all summer whether the top is up or down. It doesn't cool any faster if you set it a 65* on start but that will only keep the high fan on longer. Enjoy the ride

 

Most A/C systems, though I'm not sure about Jaguar, has a shutoff for the compressor when the system pressure is too low. If you ARE a tiny bit low on your charge, then that would certainly describe the problem you have. When the engine is at idle, the compressor turns less, so therefore the pressure would drop. Above idle and it would increase again.

 

All systems have a LOW pressure shut off switch that prevents the compressor from turning on. It is usually located near the receiver/dryer on the low pressure side of the system. If you are on the fine edge of having lower freon in the system the compressor will cycle because the low pressure switch keeps tripping . I don't believe all systems have a high pressure switch as some just have a pressure relief valve that exhaust. As the systems get older you lose freon as it's molecules leak through the hoses. This leak is extremely small and most time a quick shot of freon will restore the system for a year or so. The best way to diagnose the problem is with a set of AC gauges.

 

Hate to revive an old thread, but I'm now experiencing tberg's exact symptoms - and in LA, no less. Kinda-cold air at idle-- but not enough for a black car and 100-degree days. But when I'm at highway speeds it's fine. I've only been noticing this in the past year, so I'm hoping a little freon boost will help.
My question: is the A/C system pretty straightforward on these cars (so I could take it anywhere), or are there Jag Quirks that would require a visit to the dealer?

 

The condensers are scrap on these cars.
To change them you need to jack up the car and access from underneath, nose off.
Nose off is wheel liners off, undertray off, then 10 bolts i think it is and nose off, I leave lights in and disconnect fog lights. First time seems daunting, now its a 30 min job. Remove supercharger radiator and oil coolers. One of the o rings is a JLR part about 17gbp, didn't find anything off the shelf that fits.
Replace clips with reusable Toyota clips.

Wife has 3 yr old Range Rover...condenser already failed. Buy aftermarket from SNG Barrett.

I'd do this first then try it. Mine is perfect 12 months on. Very cold almost from the off at low speed in the last heatwave we had

 

I had the same issue. Thought it may be a filter or something strange since speed seemed to affect the cooling part. Air flow was not an issue. To make this short, I'll bet you have a compressor failing. Had mine replaced ($1780) and all is well. Except now the water pump is failing. Good times!

 

Thanks. Any way to test the components prior to replacing them? Is it worth it just to try to get a recharge? To the car's credit, the AC still works OK (not great), and it's 11 years old...

 

Take the vehicle to an air conditioning or Jaguar specialist and have the system checked with low and high pressure gauges. If the refrigerant pressure is low, the transducer/pressure switch signal to the PCM is outside the system operating range and the PCM does not engage the compressor clutch to protect the compressor.

A faulty transducer/pressure switch can have the same effect at certain engine RPMs.

 

Welp, it's the compressor. They're submitting it to the warranty company tomorrow. If they don't say yes, I'll follow the suggestion to get an aftermarket unit and have a local indy swap it out.
Will a "recharge" buy me any time on this?

 

The system can only be recharged with refrigerant once to detect leaks. If a leak is found, the refrigerant must be recovered and the leak(s) repaired before the system can be recharged again.

You can ask the shop making the compressor diagnosis if a recharge is still possible without replacing the compressor and drier.

I'm sure they're also aware that if the compressor has failed internally and there is evidence of metal contamination, the condenser should also be replaced.

 

That makes sense, but yikes. This could get pricey quick. I have found that when this dealership submits to warranty, they really submit everything, so I'm guessing I'm at an all-or-nothing place with this now. If it's denied I'll definitely ask, and let you know.

 

The compressor (and some switch/senor something) will be replaced under warranty. The condenser checks out, apparently.
Interesting tidbit: the compressor is being shipped from the UK...

 

If its an oem its shelf life is 7 yrs max, so unfortunately it will go. In the UK i believe you'd spend about 700gbp parts and labour) replacing it with a good independent mechanic using an aftermarket one - the aftermarket one will last a long time.

i think i paid 250gbp for mine, i think if i fitted again I'd be looking at 1.5 to 2 hrs using the nose off approach

 

Since the repair's being paid for, I get the part they give me, and I'm guessing that OEM is what's required. Hence shipping the part from the UK. I got 11 years out of the first one, so if I get that out of the second one I'll be more than pleased, if only because that will mean my XKR is still on the road!

ADVICE: so I got the car back, and the difference is remarkable. If you've got this issue (your car is having a harder and harder time keeping cool on hot days in stop-and-go traffic).... don't just live with it, FIX it. Whatever the money/hassle/time it takes, it's worth it. I was amazed at what I'd gotten used to: constantly having the A/C on full blast, recirculate on, and still feeling uncomfortable. I'm guessing it had probably needed replacing for at least a year, maybe two. Now the car gets ice-cold in a few minutes and stays that way regardless.
Feels more like an upgrade than a fix.