I live in a very hot climate - usually around 90 to 100 degrees daily during the summer month. The AC in my 2006 S-Type, V6, has been up to the task lately. It barely cools at idle or slow speeds, but does much better at highway speed.

Been doing an awful lot research and study and know the following things can cause this problem:

1. Fan for radiator/condenser not working at idle.
2. Condenser is clogged with bugs, debris and blocking air flow.
3. Freon levels too low and even too high and compressor kicks off at idle.
4. Compressor not operating at capacity at low speeds or idle. Or may be seizing up at idle.
4. Faulty expansion valve
5. Also seems to cool better when the inside of the car is cool, such as parking in a parking garage all day versus outside surface lot parking, Could the "Inside Temp Sensors" be faulty (very difficult to access on this car).

So I'm starting with the fan, which I verify that it is working, as i can see the blades spin down after turning the engine off. But it never runs after the engine is cut off. I also think it might have variable speeds and I don't know if the low speed operation is sufficient.

But does the 06 S-Type on depend on that single fan to provide cooling for the radiator and the "condenser" which is in front of the radiator. I don't see how any adequate air flow from that single fan could pass through the radiator and reach the condenser at idle. Or am I missing a set of electric fans for the condenser, as I did buy the car used several years ago.

At highway speed, I imagine there is enough air coming through the grille to cool the condenser and turn the hot freon gases into a liquid for cooling.

As for other possible causes, I had the DCCV (heater valve) and Climate Control Module replaced about three years ago. Surely the parts will last longer.

I see the "hot AC air at idle" is a common problem not just in just Jaguars, but other cars as well. And no one seems to have a good solution, so lots of drivers just live with it and hope the traffic light is not too long. I feel their pain, or heat!

Any thoughts or insight would be appreciated.

Earnest
Hot in the deep South.

 

Dear Sweaty Earnest,

A tip of my orthopedic hat for thinking this one through and/or overanalyzing the problem. I thought I was the only one who did that...

What does your exterior thermometer read? If out of whack, this can affect the automatic control system.

Have you put the system in manual mode? Drive the temp setting down until it reads LO. That bypasses most of the automatic controls. This is great for troubleshooting.

I don't think your DCCV is at fault because you'd be getting even more heat at higher RPM. The heater isn't very efficient at low RPM, so you'd get less heat at a stoplight, not more. You can verify this with a thermometer in the center outlet duct. If warmer than the ambient air, the DCCV is adding heat, whether inadvertently commanded or if just stuck open. If the outlet air only reaches ambient temps, then no heat is being added.

Based on your scenario, here are the three most likely causes, in no particular order:

1) Low refrigerant
2) Low refrigerant
3) Low refrigerant

This is based on the assumption that the AC has worked well in the past, and it's been a while since the system was last serviced. Refrigerant will slowly leak from even the tightest system. If it's been at least three years since the last service, I personally would go straight to that. Your symptoms match exactly what my '02 does if the refrigerant is a little low.

Before you ask, gauge readings can NOT tell you the quantity of refrigerant. Gauges can help decipher compressor performance and things like that, but can't really confirm if the correct level of refrigerant is present. The only way to know is do a full evac and recharge with a measured amount.

Evac and recharge is the official party line. With that said, on a system that is providing at least some cooling, I've added small amounts and watched carefully for an improvement. The hard part is actually stopping if no improvement is noted, because the problem lies elsewhere. But if it's been several years since the last measured recharge, I can practically guarantee at least a small amount has leaked out. With reasonable safety against overfilling because of that, you can add three or four ounces and see what happens. Remember, if no improvement, stop. Don't just keep adding more because that won't help.

If you're not sure about adding a little refrigerant, you can always do the full evac/recharge instead and know for sure.

There's a tech bulletin about a spring in the compressor, or something like that. That's another possibility, but I think the symptoms are the same as low refrigerant. With the same symptoms, I'd probably shoot first for the more common scenario of needing refrigerant and see what happens.

 

+1 on having the refrigerant level checked by a competent air conditioning specialist. Since the refrigerant is added by weight, there is special equipment needed to accomplish this correctly.

The system should not lose refrigerant under normal conditions, so you must check for leaks. Fittings can leak at their o-rings over time, so they should be replaced as part of servicing the climate control system. If refrigerant is leaking from the compressor seals, the compressor unit and dessicant/dryer should be replaced and the system evacuated and recharged with the correct amount of refrigerant.

In the meantime, reverse flush the condenser and radiator with a garden hose to remove debris clogging the air flow. This can help with returning the refrigerant to a liquid state. As you noted, there is only one fan for cooling the engine and pulling air through the condenser. If the fan continues to run when the engine is turned off, the thermostat may need to be replaced. The fan should begin to run when the air conditioning compressor is engaged, even at an idle. If not, check the electrical circuit beginning with the fuses.

 

The fan is plenty good enough if the rest of the a/c system is working properly. (I think the fan blows (pushes) not pulls, btw, and the a/c rad is first.)

 

Thanks guys for the replies.

As my "hot at idle" mystery continues, here a report on my commute to work this morning. I park under a carport at home, so the interior was relatively cool as I begin my journey:
------------
At startup
------------
Outside temp: 79 (based on dash display; verified by my outside thermometer)
Inside Car: 80

-------
Commute to Office (Interstate highway, 70 mph)
-------
Outside temp: 85
Inside Car: 40 (AC working well at highway speeds)

---------
Arrive at work
--------
Outside temp: 85
Inside Car: 50 (encountered a few stop lights after exiting interstate)

So as the outside temperature rises, the AC becomes less efficient, but still comfortable at highway speeds, until a stop at a traffic light. But should I have to run an errand at, let's say, mid-afternoon, when the inside car temp will be around 100, I'll be hot until I can get on the Interstate and get up to higher RPMs.

I will have the freon levels checked next week. In the meantime, I need to travel only on the Interstate, stay off city streets and only travel in the early mornings : )

The life of a Jag owner is never dull.

Earnest

 

Dear Sweaty Earnest,

One more suspect I forgot to mention:

The compressor clutch could be slipping. If so, that can also cause poor performance at low RPM, but with adequate cooling at higher speeds.

This happened on my '02. It was caused by arcing and pitting inside relay #8 in the front power distribution box. This extra resistance decreased the voltage reaching the compressor coil and caused slippage.

I swapped relay #8 and relay #11 (fog lamps) for troubleshooting and got full cooling back.

Wiring diagrams here, courtesy of Gus:

http://jagrepair.com/images/AutoRepa...cal-2006on.pdf

Details are in figures 3.2 and 8.1

 

Best have your pressures checked at ambient temperature. But based on your output temps sounds like all is working well..

 

I had this EXACT same problem 4 years ago. I would be at idle and this is when I first noticed it and if I slipped the car in neutral and move upward on the rpm it would get cooler. Put my gauges on the ac system and found the needle bouncing all over the place. Had extended warranty and it was a bad valve on the compressor. Had it be replaced. There are ways to deal with just the valve and there are posts on the forum about that.. However this is compressor related I am sure.

Tom in Dallas/Plano
05 S-type 3.0 92k

 

There is a TSB to reverse the valve spring in the a/c compressor so there is better refrigerant flow at low engine rpm(ie., idle).

 

Well aware, however for an average driver, the R&R on the valve/compressor may bring about, in the learning curve, a series of issues unrelated that take a 2 hour job to 6 or 7.. New compressors can be had for reasonable price as long as you do not go to the dealer. For $199, Rock auto sales a component kit that includes new compressor, receiver/drier, expansion valve and a number of O-rings, seals and gaskets. More Information for GPD 9633338


Tom in Dallas/Plano

 

My indie modified the valve/spring per the TSB instructions and it made a HUGE difference in the performance of my 2001 S-Type A/C, esp at idle and stop 'n go driving. That car is now tooling around hot and humid Miami Florida. Its A/C works like a champ.

A new o-ring cost me $15, additional parts and labor were approx $100; so the entire cost of the procedure was nowhere near the cost of purchasing and installing a new compressor & dryer (roughly $500). To me, trying the less expensive alternative recommended by Jaguar was a no-brainer.

Modifying your compressor valve spring might resolve your problem as it did mine, and at a much lower cost than replacing the whole shebang. The important things to ascertain first are that your system has the correct refrigerant level and that it is functioning properly in all other respects.

 

I am curious on the TSB which was issued in the beginning 2010, if the AC units after that- provided by Jag- included the modification??

Attached is the TSB

Tom in Dallas/Plano

 

No new cars were made after 2007 so who knows what jag might do with any parts in stock?

 

That is pretty clear, that was why I was asking to see anyone might have gotten parts after 2010 and attempted to make use of the suggested TSB and found it was represented the TSB.

Tom

 

OK, that was not clear at all. I don't recall anyone buying a new compressor from Jaguar since that date, but maybe someone will post who did and also checked the mod.

 

New compressors don't have the valve,see Rick's picture below. The valve is below the black cover in the unit on the right the new unit just has a blank well in the casting.

 

Thanks much and that is something I can look for. I had to get a new compressor in mid 2012 and was just wondering if I had the modification and apparently they redid something.

Thanks a bunch.

Tom

 

That new compressor above is an OEM that I purchased off eBay. Unfortunately I have no clue when it was manufactured.

 

Just wondering if you resolved A/c not cooling at low speed? Cheers

 

Don't hold your breath. This is an older thread, and Sweaty Earnest, as he came to be known in forum folklore, has pulled yet another Steve. Named after another forum member, that's a phenomenon, sadly all too common, where you start a thread, get lots of detailed advice, and then never come back to tell us what how it all panned out.

I would suggest starting a new thread with your query, rather than hope this one ever gets resolved. In the meantime, work through this troubleshooting guide:

Everything You Ever Wanted to Know About the HVAC System But Were Afraid to Ask


Specifically, work through post #2 to verify the Dual Climate Control Valve is operating properly. A fault here (VERY common) can mimic an AC problem. Next, determine if your problem happens in Auto mode only, or Auto and Manual. If okay in manual mode, work through post #3. Otherwise, see post #4.