I have just checked the AC pressures on my car (I have warm air) and the low side is approx right (50psi) but the high side is low, only about 120.

Anyone tell me what that points to?

I have googled but struggling!

Thanks

Could be low on refrigerant, the wrong refrigerant/oil quantities added, incorrect refrigerant specification (some of the 'top up' bottles aren't actually the right refrigerant). Or mechanically it's likely to be worn seals in the compressor preventing full pressure being reached or pressure blowing by the seals. 2012 (L322) 4.4TDV8 Vogue SE, RSE, Fuji White over Arabica.
Previous V8s: BMW 645Ci, P38 4.6, P38 4.0, Merc CL500
Previous others: Honda x1, Volvo x7, Rover x6, BMW x6, Ford x1, Mercedes x2, Skoda x3, VW x2, Renault x2, Citroen x1, Mazda x3, Nissan x1, Audi x3, Kia x1, Fiat x4, Subaru x3, Austin x2, Triumph x2, Jeep x2, Hyundai x2, Lexus x1, Mitsubishi x1, Saab x2... and some others I've forgotten!

You can only rely on pressure readings once the refrigerant charge weight is known to be correct, there needs to be enough refrigerant to allow a change of state from gas to liquid once compressed. Before recovery, I'd suggest a leak test with a decent sniffer and a visual check for corrosion, stone damage or (compressor) oil staining around the flexible hoses, condenser and charge points. If all OK, then recover, VAC, test under VAC then pressure, if OK, then recharge with the addition of 5-10ml of UV compressor oil, running the system for a good 30 mins to distribute the oil. Monitor with a UV torch after a week or so.

How did you arrive at the 50psi pressure? That is way too high in a compressor running situation and very low in a static situation unless you are in the arctic. If we assume that is your static pressure so you are low on refrigerant.

If you system is R134a I can set you up with gas cans and charging hose or you can get someone out to do it for you or take it to a garage for a check up and top off.

I used some gauges in a kit (only cheap ones but only wanted to get an idea)

I used the following chart to see whats OK or not-ambient temp at the time was 29 degrees, hence my assumption that the low side was OK.

I havent had chance to anymore investigating as I have had coolant hose issues (a mix of poor garage work and then the fan chewed through one) and I have been fixing that as a prioroty.

Post edited as I uploaded the wrong chart!

If you a running in a fairly high ambient of 29C then the pressures are liable to vary depending if you are testing first thing in the morning to testing last thing in the afternoon as the temperature of the system under the bonnet especially if the car is outside is unlikely to be 29C.

You should check the system pressure on a steady condition day, we get a lot of 15C days in the UK - ideal, before starting the car or doing anything. This site gives the static pressure for the gas at any given temperature. If you fall under the gas pressure then you will have lost a lot of the charge.

https://learnmetrics.com/r134a-pt-chart-pr...ure-chart/

The L405 has an AC module (so maybe the L322 does to?) where you can read through the OBD port with a tool all the AC data including system pressure, actuator position and compressor state plus voltage. I'd guess you are down on the charge which is normal as a AC system will vent around 2% of charge a year through hoses and seals. So any system needs a check/top off every 5 to 6 years to replace the vented gas.

If you go to an AC engineer, they will pull out your remaining charge, check the system for leaks and then add back and top off to the OE charge weight.

I will take it to an engineer. I have finally found someone who seems to understand AC so in the next few weeks I will go and see him. (I am still waiting for delivery of some coolant hoses etc so cant go anywhere until then).

I did have it checked and filled at a local French garage, but nothing changed after the visit. Although they had an AC machine, I was not confident they knew what they were doing!