Because weather had not been hot I had not noticed that the A/C was not working very well.
Went through the guide and found that the DCC was not closing properly on both sides so changed it.
Going to to LO now from start means cold tubes from the DCC. but the AC is still crap. Checked A/C pump clutch appears to be working ok
swapped fuses also. Checked high side of compressor with IC930 and pressure was around 130PSI and about 150+ with 2k Revs.
Checked low side and pressure was over 80PSI, not running. Wondered if maybe previous owner had put in more gas because of DCC problem.
Let out some gas and reduced pressure to 45PSI on low side. Tried car again. Now NO cooling at all!!! (Only underbonnet temp??)
Getting out trust IC930, Pressure around 110PSI, with some revs 130PSI, Switching off engine pressure drops to 90PSI. Measuring with meter on low side shows 80PSI again!!
Lost completely any ideas anyone?

 

That is about right for the engine off on a day around 80F. Pressure equalizes throughout the system when not running. Please, please, please, you will need to understand that the pressure of refrigerant in a system does NOT correlate to quantity. The 80 PSI you recorded means the system had SOME refrigerant, that's all. Going by pressure alone, we can NOT know whether the system had the correct amount, a little low, or a little too much.

More details about the pressure/volume relationship in post #4 here:

https://www.jaguarforums.com/forum/s...2/#post1714573




Okay, here's one area where the pressure reading is useful. After bleeding off some refrigerant, you now have way too little. That's a problem. It's important to have the correct quantity of refrigerant. Pressure means very little, other than how well the compressor is working. I'd suggest doing a full evacuation and recharge, so you know you have the correct quantity. Don't worry about the pressure values for now.


https://www.jaguarforums.com/forum/s...ics-faq-55219/


If that doesn't return the cooling to normal, please continue troubleshooting per the guide linked earlier.

 

If you do a full evacution and recharge, i suggest replacing the receiver dryer if it is age is unknown....as per Karl, you need to start with this procedure....the vacuum holding test will give you a good indication of system integrity...AC work can get expensive quick without thourough troubleshooting....if possible use a 2 stage hvac pump if doing it yourself

 

I am getting it done tomorrow by a pro! Vacuum and refill.

 

OK, Vacuumed and recharged with 700g of A134.It is cooling a bit better, on LO , measured in the vent it gets down to 20C, outside temp 30C
with engine hot. Right vent about 5C higher. Raising the temperature to about 23.5C on LH causes the blower to start reducing output.
High side pressure at idle 130psi, at @2500 rpm about 210+ psi, looks like the compressor is working OK. I will try it cold tomorrow so that the coolant is cold to see what the vent Temp is.
If that looks somewhat better I will clamp the common pipe on the DCC. and try it hot. I guess that a stuffed sensor could cause the ACCM
to modulate the DCCV incorrectly so blocking the tube would stop heat entering the core.
This morning, outside temp 27C, 30C in car. Started up on LO at engine idle, Temp in vent dropped steadily to 12C in a minute or so before rising fairly rapidly to about 18C and remaining there. ( Hot/warm water arriving from the DCCV ?)
Increasing LH setting to 19.5C caused the blower to slow down, on the RH increasing the setting to 24.5 caused the blower to slow down ??

 

Vacuumed the Cabin sensor and sprayed with contact cleaner, now there is about 5C+ of leeway on the blower being reduced on both sides.
Had a go at cleaning the Condenser, when everything was cold on idle the vent temperature went down to 8C (Ambient 26C) then went up to about 15C.
At 50Kph Engine hot, vent temperature was about 10C on one side 15C on the other side. 28C ambient.
Think the Fan is not very efficient, it just holds a T-Shirt on the grill. (Bearings, brushes lubrication etc.)
How do you get the Evaporator sensors out, or I guess it is easier to unplug the CCM and measure the Resistance at the plug of all 3 and then worry about getting them out if necessary.
Getting there slowly...................

 

Is this the Evaporator sensor, above the Acc pedal, Where is the connector there does not appear to be anything attached to this?

Is this the sensor, there does not appear to be anything attached to it!!

 

I missed this when first posted. That sure sounds like uncommanded heat making it past the DCCV. You had previously mentioned replacing the DCCV, but did you test the new one after installation?

The DCCV has a very high failure rate. I would not be surprised if the new one was bad from stock. Details of how to test in the troubleshooting guide, post #2:

https://www.jaguarforums.com/forum/s...ol-how-185002/

 

Yes, that is the evaporator temperature sensor in the middle of the picture. When installed, you can't see the rest of the probe, as it fits into the evaporator case. Please see post #3 in the troubleshooting guide for more details.

However, I'm afraid you may be getting ahead of yourself. For troubleshooting, the first step is to verify the DCCV opens and closes properly, discussed in my previous message. From what you've described, your new DCCV could be bad, so definitely check that.

The next step is to turn down the selected temperature until LO is displayed. This puts the system in manual mode and bypasses most of the automatic inputs. Go for a test drive and see what happens. I haven't seen any mention of that yet, or maybe I missed it. This step is important because it makes sure the AC system is capable of putting out an adequate volume of cold air.

Reading between the lines, I think you may actually have insufficient cooling in both manual and automatic modes (post #4). If the AC was normal in LO, you'd want to follow post #3, but I don't think that's the case.

Also, watch the compressor clutch with LO selected. If the face of the pulley is spinning, that means the clutch has been commanded to engage. If the vent air is still too warm, it's not caused by an input problem, such as the evaporator temperature sensor. The problem is elsewhere, such as a slipping clutch or uncommanded heat from the DCCV.

 

The DCCV, is working OK mechanically. Before fitting it I tested it and it worked perfectly. Going for a test drive between 50-60 Kph with LO is 10C on the Left side but 15C on the Right (this may be better now as I cleaned the condenser with high pressure water jet, will try this out on a run tomorrow am). On manual the Left side is working better, when set to 17C raising the setting to 18.5C started to turn the blower off. After cleaning the cabin sensor
the setting could be raised to 25/6C before reducing the blower. The right side was already like this. The right side is ALWAYS 5C higher than the Left. I think the DCCV is being modulated by the CCM erroneously. I guess I will have to Clamp the common pipe to eliminate partially the DCCV.
Looking at the sensor in the picture there are no wires attached to it that I can see? I have an Ic930 and I remember seeing a strange temperature regarding the expansion temp which appeared to follow the set temperature. There are no DTC codes apart from the irrelevant B1625 one.
The visible wires in the picture are taped up!
One thing I really don't get is the entry and exit pipes at the bottom of the DCCV what is the point of it?

 

The 5C split between the two sides is a problem. If the right side is always warmer, even in LO, this means unwanted heat is dumping into that duct. There may be other problems, but it sure seems you are getting uncommanded heat in at least the right side, possibly both. With LO selected, both sides should be equal and as low as the AC system can go. This mode bypasses most automatic inputs. The only time one side should be warmer is in automatic mode, with one side set higher than the other.

For now, do all of your troubleshooting in LO. Worry about the automatic control later, as it may not even be an issue. Same with the evaporator temperature sensor. It is always part of the AC circuit, but can't cause a split between the sides. Leave it alone for now.

You can clamp off the heater line and hopefully that drops the temperature. You mentioned testing the DCCV before installation. How did you do that? However that was, something isn't right once installed. Perhaps there's a wiring problem, I don't know.

Another quick way to test the DCCV is to select LO, switch off the AC button, and go for a test drive. With these two settings, the air should be neither cooled not heated. The air from the vents should be within a few degrees of ambient. I suspect you will find the air significantly warmer than ambient, meaning uncommanded heat. That needs to be addressed first or you will be chasing your tail.

 

I checked the voltage before on the connector pins from the DCCV under the panel at the LH side of the dash about 14V with AC off and 0.3V with the AC on.
I don't have a scope here to see if anything is happening on these lines.
I will try the LO and AC off as well tomorrow morning as I will go about 50Kms at reasonable speeds.
Will be back tomorrow !!!
BTW re the connectors/wires to the sensors?

 

OK this morning went about 30Kms with LO and no AC connected. Lovely sunny day with ambient temperature 27C, 70% Humidity. Temp got up to mid scale in about 10mins. The temperature from both central vents was pretty much constant whether in movement or stopped from when the T gauge got to about 1/4 at 30C or just under which I think means that the DCCV was closed.
On the return trip AC on LO, Ambient was 30C and the Left side vent varied around 12C to 14C when stopped for several minutes in traffic, Right side was constantly 5C higher. Never went above 70Kph the whole time, generally around 50Kph.
Tomorrow I will disconnect the Brn/W and Brn/G wires from the connector in the LHS of the Dash panel and connect them to the chassis, this will keep the DCCV closed regardless of the A/CCM. This shouldn´t cause any probs with the A/CCM I hope, as they will not be sinking anything.( I presume they are FETs not relays as the modulation times are short 3mS?)

 

A/C on and LO, Shorted the two wires N/W and N/G to chassis (DCCV CLOSED) and lo and behold the temperature of the 2 vents was the same at 15C. Removing the S/C to chassis, voltage on the wires goes back to 0.24V on each side and still 15C on the Left and the right side vent rises to 20C, ie 5C higher than the left. This means that the A/CCM is modulating the 0V line on the right side of the DCCV and allowing some heat through. ?

 

Trying to follow what you've reported. I'm having trouble understand some of what you're doing. The big thing you should be looking for is the vent temperature with LO selected and AC switched off. This means no heating or cooling should occur on the air passing through the vents. IF (big if) the DCCV is closing properly, the vent temperature should be very close to ambient exterior air. You did not report the air temp from the vents in this condition. This is the BIG test. If the vent air was much warmer than exterior air, your DCCV is letting heat in the duct somehow.

Please post the air temp at the vents from your test drive with LO selected and AC off. Measuring at idle while parked is not a valid test, and can give misleading results. You want to be moving, so you're drawing in fresh ambient air, not warm air from the engine compartment. (The air intake is at the base of the windshield). You want the engine speed around 2000 RPM or higher to compensate for the poor coolant flow to the heater at idle. If tested at idle, and the DCCV is only partially blocked, you will get a misleading indication of no unwanted heat.

Or just clamp off the return line from the heater core. If your AC operation returns to normal, then you know how to proceed. I see you making lots of work for yourself, but nothing you've reported so far is conclusive.




The fact that the one side keeps showing higher than the other with LO selected makes me think at least one side of the DCCV is failing to close. Now whether it's a bad valve, wiring issue, etc., we don't know. Heat from the DCCV is the only way for one side to be warmer than the other.

 

One possibility is the DCCV (or control circuit) is bad on both sides, but the right side is worse. By supplying a ground to each solenoid, that only shows that some control is possible, perhaps within a limited range. It does not conclusively show each side has a full range of travel, closing fully and then opening fully.

 

This is what I did.
OK Yesterday morning went about 30Kms with LO and no AC connected. Lovely sunny day with ambient temperature 27C, 70% Humidity. Temp got up to mid scale in about 10mins. The temperature from both central vents was pretty much constant whether in movement or stopped from when the T gauge got to about 1/4 at 30C or just under. That is 3C of difference,which I think means that the DCCV was closed.
On the return trip AC on LO, Ambient was 30C and the Left side vent varied around 12C to 14C when stopped for several minutes in traffic, Right side was constantly 5C higher. Never went above 70Kph the whole time, generally around 50Kph.
Tomorrow I will disconnect the Brn/W and Brn/G wires from the connector in the LHS of the Dash panel and connect them to the chassis, this will keep the DCCV closed regardless of the A/CCM. This shouldn´t cause any probs with the A/CCM I hope, as they will not be sinking anything.( I presume they are FETs not relays as the modulation times are short 3mS?)

This morning set to LO, A/C on. Both sides of the DCCV were physically taken to Chassis 0V shutting the DCCV on both sides and the proof of the pudding was that the vent temperatures on both sides were exactly the same at around 15C (Increasing engine revs 2000+ the T dropped under 10C again on both sides), This test is better than clamping because it shows that the valves were operating. Returning to A/CCM connections with no other changes produced a 5C increase on the Right side so I guess that the A/CCM is faulty.
connecting the DCCV correctly with no other changes to the A/CCM again caused the temp on Right side to be 20C.while the Left side remained at 15C.

 

LO A/C off, Only 3C difference Very sunny day, 27C Ambient and 30C vent both sides. Mixed conditions on dual carriage way and 5K of motorway at 110K but generally under 70K .
Return trip with AC on and 30C ambient.

 

is something getting lost in translation? Getting kinda frustrated here.

I've been asking for a numeric value of the vent temperature with LO selected and AC off. You replied "The temperature from both central vents was pretty much constant". On your 27C day, I'm looking for [Insert numeric value here] from the center vents.

As an example, I tested my car on the drive home.from work. 82F outside. In Celsius, I think that's still 82F. LO selected on the control panel. AC button switched off. In theory, there's no heating nor cooling of ambient air passing through the ducts. My trusty little thermometer showed 82F on both sides. Now that's a good reading, telling me my DCCV is fully closed on both sides when commanded.

 

OK, LO, NO AC. Difference was 3C over the 20 minute driving period ie. 27C (80.6F) Vent temperature on both sides just under 30C (86F)
Your 82F in 82F out assumes no under bonnet heating whatsoever.
I hope this is clear.
BRs
Mike