Well team this will be my 3rd year struggling with a weak ac system in Texas Heat.
The car provides little cooling at idle or low rpms which is becoming more of a big deal now that the temps here hit 88 degrees today combine that with a black interior on a black car, no bueno.
As the car moves for over 5 minutes I get some relief but little, once summer hits at 100-110 degrees I will get no relief. Unless I drive for a good while about 15 minutes on the highway.
In 2016 I replaced the Thermal Expansion Valve and dessicant bag in the condensor, not much change. I replaced the solenoid valve within the AC Compressor and got better readings on the pressure gauges and slightly better cooling. But bearable.
Last summer (2017) I went ahead and replaced the AC Compressor with a remanufactured unit from RockAuto and the Condensor as well. Recharged according to spec and got better cooling. The pressure gauges were within spec as well. I can't find much research on AC repair for this model.
Sorry for the long story it's embarrasing no AC in a nice car. Any thoughts on what I should do next? Diagnostic advice? Am I looking at a bad evaporator core?
Thanks in advance guys!

 

It is also possible you have an electrical fault.

Well you have replaced everything except for the evaporator and lines.

I'd check the PWM signal to the compressor as this regulates the pumping rate of the compressor.
To do this you need to put a handheld CRO on the signal and go for a drive. Revving in neutral wont do it.

Assuming that's OK, plan for an evaporator and while it is out blow out the lines.

You can get a handheld or USB CRO under $100




Cheers
34by151

 

Did you replace the clutch that is connected to the compressor?

I would also consider tinting the car. No black on black car will ever be cool in hot sunny Texas heat.

 

I'm wondering if the seals on the blend doors have deteriorated, and heat is being mixed in when it shouldn't. I have found little pieces of foam behind my dash vents now and again. I also feel like the AC performance in my car is not as good as many smaller/cheaper cars, but I have never touched anything my system.

Do you pull the fuse for your aux coolant pump in the summer? I notice a definite improvement when I do that. It won't prevent heat from the core (only way to do that is clamp off one of the heater hoses), but helps at low speeds because it's not forcing coolant through the heater.

I doubt you have a bad evaporator core. You should notice if you're losing refrigerant due to a leak. The only issue there might be that it could be dirty/clogged from airflow, but with the cabin air filter I think that's less likely.

Also, what are your center vent temperatures? Measure with a thermometer, not an IR gun.

 

What are your head and suction pressure readings you're getting? You say they "look good", and if that's true, that rules out a lot of problems.

*Edit* I re-read your post and it appears as though you took the pressure readings last summer. Do you know what they are now?

 

+1 on a blend door problem being a suspect.

There's an airmix flap, a bypass/defrost flap, a face/foot flap, and a fresh/recirculation flap. They are all controlled by actuator motors. You might try varying all of your vent modes to see if you can determine if any of these flaps are not moving properly - particularly the airmix flap, which, if not moving and/or sealing properly, can allow air to pass through the heater core at all times.

It would be worth having the car scanned by IDS/SDD or another system capable of reading the proprietary Jaguar Body, Chassis and Network codes, since a lot of climate control issues do flag diagnostic trouble codes that may give you some clues.

Cheers,

Don

 

The heater matrix remains hot all the time and is shut off by flaps. In fact on most climate control systems, even in winter the air goes through the evaporator first to get the water vapour out, then into the heater to warm it up.

On my wife's New Beetle which doesn't have climate control, one can close down the heater, and also switch off the air con. So it's fully controllable, albeit you can't just set a temperature and it remain the same as you drive from a cold England to a hot Rome, as I once did on 2007 with my Rover 75.

 

There has been a post where an owner found that a piece of foam had fallen off

inside the climate 'box' and was restricting flow, also the little motors which control

the flaps can fail. Due to a wiring fault in one case.

 

I am experiencing the same air conditioning issue when the car is stopped. At speed the air conditioning is fine, but a stop light brings on the warm air. All pressures are within specs, no leaks, cabin filter replaced - would love to get constant cold air again.

 

With the onset of hot weather here I've recently helped several friends with A/C issues and have been reminded that in warm temperatures it seems to be more difficult to charge the system by pressure readings alone and very easy to overcharge the refrigerant. One clue of an overcharged system is if the compressor clutch engages/disengages frequently, especially if the clutch engages very briefly then disengages. In hot temps the clutch should stay engaged most of the time. If yours doesn't, try evacuating some of the refrigerant to lower the system pressures and watch the clutch to confirm it is remaining engaged continuously.

Cheers,

Don

 

Please note that the compressor clutch on these XJs is viscous and does not cycle--it will not click on and off like an electromagnetic compressor clutch.

I do agree that the best way to charge this system is by weight. You should evacuate the system and recharge the specified refrigerant by weight. With these small systems it's imperative that the charge level be correct.

NDW, sounds like you may have a weak compressor. If you put the car in neutral and hold engine revs at 1500 rpm, does it blow cold again?

 

How hard is it to check and/or replace the foam seals in the heater box. I have weak ac and will need to change the heater core due to low heat on the driver's side (already changed the aurilary pump).


Should I plan on fixing the seals while the heater core is out? If so I'll change it now rather than in September as I currently plan to.

 

Hi mhamilton,

Thanks for correcting me regarding the X350 A/C compressor. Fortunately I haven't had to work on one yet!

I just took a peek at pdf page 96 of the Chassis section of the Workshop Manual, which states the compressor is clutchless and operates all the time:


However, the 2004 X350 Electrical Guide shows a clutch in the upper right corner of the Climate Control schematic, pdf page 81, with what appears to be a PWM control signal:



Since I'm fairly certain the compressor is belt-driven, it does seem as though there must be a clutch of some sort. You mention that the clutch is viscous, but the Workshop Manual says the compressor is clutchless. Can you make sense of this for us?

Thanks!

Don

 

Hi Don,

You're right on that, the manual does say the compressor is clutchless. It appears the compressor is controlled only via the variable displacement function, while the hub is driven 100% mechanically full time.

I believe the "compressor clutch" on the schematic is just a typo, that PWM signal is actually controlling the variable displacement solenoid on the compressor. Since it is the only electrical connection to the compressor, it must be the solenoid.

What the manual says must be true. There is no clutch (viscous or electromechanical) and the a/c is only varied via the PWM displacement solenoid. I believe our compressors are the Sanden model V6, which is similar to the V5:

 

Thanks mhamilton,

That's a very cool compressor design!

Cheers,

Don

 

On Saturday, it was 105 here in NE Texas, the car was sitting in a shade free concrete parking lot for about 3 hours in the middle of the afternoon. I went out early from the party to start the car and attempt to cool it down before my wife and the other couple came out. I sat for at least 5 minutes with about 1,500 RPM and full A/C engaged with very little cool air coming from the vents. Once I started moving, the air started getting cool coming from the vents, but I only had about 5 miles to drive at less than 40 mph so the car never cooled off. I am leaning towards the fan not operating at correct speed or the radiator being full of debris.

This morning I started the car in a 74 degree garage, put the A/C on max low temperature and recirculating - the fan did turn on - but it didn't seem to be moving as quickly as I would think it would with max A/C load being requested. The condensor was clear, and the back of the radiator looked clear as well.

My plan of action is to take it to an independent Jag tech that is well respected and look at the codes and the fan initially.

BlackKat has replaced many parts without repairing the problem, so I am thinking the A/C system is fine mechanically at this point. I will update as this problem gets resolved or gets more frustrating.

 

It also has a shear section in it so that if the compressor jams or seriously overloads then the pully-to-compressor shaft breaks and the pully can continue as an idler, and it doesn't snap the belt.

 

I agree with your assessment--it sounds like the condenser has insufficient airflow. It is definitely possible your radiator fan is not spinning fast enough, the PCM controls it via the PWM module and will command a certain % based on engine temp and a/c pressure, but it doesn't know how much air the unit is actually moving.

If you wanted to test this theory you could idle the car with a/c gauge set on. If you mist the condenser with water and see the high pressure drop like a rock, then you have an airflow issue.

Also, less definitive, but a quick check, the radiator fan should be able to easily suck a shop rag to the front of the condenser coil.

Good luck with the shop--let us know how it turns out.

 

MHamilton,

Thank you for the tips. Here are the results. I pulled the car out of a 74 degree garage into 97 degree full sun heat. Drove the car for about 5 miles to get the engine up to operating temperature. Air conditioner was set to 'LO', recirculating and high fan. Don't pay attention to the ambient temperature on the control panel, it takes a long time to accurately reflect the outside temperature after it comes out of the garage.

Car was cooling well when pulled out of garage, (Duh). Pulled the car back to shop and left on hot concrete in full sun. First thing was to try the rag test, which the fan held the rag to the condensor easily - actually sucked it onto the condensor. I replaced the black cover after removing the rag for the remaining tests.

Second, hooked up the gauges with these initial readings on the outer black scale: 32 /252

Third, here is the vent temperature reading prior to misting: 68 degrees

Fourth, after misting cool water on the condensor, here are both readings: 25 / 145

Fifth, here is the vent temperature after the misting of the condensor: 68 degrees

When I misted the condensor, I heard the fan go into a slower mode almost immediately. After I stopped misting and it dried off, the fan kicked back into high speed.

After sitting on the hot parking lot running full AC for about 30 minutes, the low pressure was 41, the high pressure was 300, and the vent temperature gauge read 90 degrees and climbing. The cooling fan was running on high based on the sound.

I don't know what to make of this information - scheduled to go to independent mechanic on Tuesday.

Thank you for any help.

 

Hi NDW,

I'll defer to mhamilton when he gets a chance to reply, but in the meantime it looks to me like your low pressures are too low and your high pressures are too high, at least relative to one another. In other words, as high as your high pressure is, I would expect to see the low pressure higher. One possible cause of those readings is an obstructed expansion valve/orifice.

Another observation is that a possible reason your vent temperature began climbing toward ambient is that with a refrigerant high side pressure above 300 psi the pressure switch may have disabled the compressor. If I understand the Workshop Manual correctly, in the X350 a single pressure switch connected to the ECM disables the compressor when the refrigerant pressure is too high or too low.

I'll be interested in what mhamilton has to say.

Cheers,

Don