We don't have much need to investigate the cooling abilities of the AirCon in the UK. I'd noticed the XK was adequate but not as good as my previous two XK8's or X308. Recharging with a DIY kit I'd used on other vehicles showed it was up to capacity.



However, on a recent trip to southern Spain where the temperatures hit 98 deg F, the AirCon was only pushing out barely cooled air despite showing 58 deg F on the display screen.

Back at home in the UK, I took it in for a check yesterday. The AirCon charge is 700g but mine only contained 17g. Not surprising it was performing badly!



I was concerned with such a low charge that the system could have a leak but the procedure checks this out. The professional recharge equipment operates as follows:

1. checks existing charge weight
2. completely empties the system
3. applies a vacuum to test the system for leaks (10 minutes)
4. refills with the correct weight of R134a and volume of PAG oil

The AirCon feels considerably colder now (although still displaying the same 58 deg F on maximum LOW). Unfortunately I probably won't have the opportunity to check it in anywhere 90 deg F external temperatures for a while.

Two lessons learned here:

1. DIY AirCon recharge kits aren't reliable
2. the displayed temperature is misleading

Graham

 

If I remember correctly the "displayed temperature" is the temperature you have the unit set to. It is not the temperature in the vehicle. The way to check it out, is to set the temperature(s) to where you want it/them to be and see if system cools/heats the vehicle to the set temperature(s) and then the fan slows down to maintain the set temperature(s).

 

wow, that's low Graham, glad you caught it in time as it could've got expensive quite quickly due to low fluid levels needed to lubricate the system.


Presumably there's enough oomph coming out the blower and your pollen filter is fairly new, not clogged, no restrictions to airflow?

 

OK, for what's worth, I've always been of the opinion the R134 was not up to the same level as R12. To make or evac the same BTUs in the equivalent system one needed a larger system, I.E condenser , compressor, evac etc. That being stated, these systems have a hard job to cool down an auto interior to comfortable setting in a very short time. Especially when the indoor is 125+. When you get the opportunity, check the output at the central vent with a pencil thermometer. It should be 20-30 deg F. from ambient at max air. Also, try using the re-circ for awhile. Good luck....

 

Check the charts on temp vs humidity vs vent temps. https://www.google.com/search?q=ac+v...9%3B1000%3B436
These cars were designed for 134A so there should not be a cooling problem. The systems are larger in capacity then the equiv. R12 systems . Vent temps will never hit 30*F because the evaporator would freeze up and you would have no air flow. When you look at a AC pencil temp gauge you will see the sweet spot is between 45-65*

 

Yep, 'bout where I'd put the drop....ambient 95 output 65, or so ( at peak efficiency). Yes, they do need to be designed around their capacity to pull mega BTUs in a heart beat. Those charts mean something to an HVAC and one who knows the importance of their values. However, the average gearhead, unless skilled in the trade, otherwise way too busy to comprehend.
I just look for the drop at the center vent or as you stated the " sweet spot".
Nice charts!