JB74 AC issues

See if you can find somewhere to re-gas it that won't charge you if the re-gassing doesn't improve the temperature figures.

Otherwise it will be best to get it diagnosed by an air-con specialist.

Paying for a re-gas with R1234YF is phenomenally expensive, and could just be throwing money away if you believe the compressor is failing.

The compressor will be noisy if it is low on gas as well as if it is worn out, but there is a pressure switch that won't let the compressor run if the gas is too low.

In my experience (two out of two cars owned from new), AC compressors only run for about 4000 hours before they wear and produce a black sludge that blocks the expansion valve in the evaporator.
When this happens they won't cool any more despite being full of gas.
(One of mine just wouldn't cool despite being full of gas, the other would cool a little when filled with gas, then I think it vented the gas through the shaft seal due to overpressure and would run out of gas in a week or so. It happily passed the vacuum test and passed a pressure (leak down) test with nitrogen too.

Re-gassing works for the majority of drivers who keep the air-con off when it isn't hot so the seals dry out and the gas escapes.


So you can either not use it, and the gas will escape, or use it all the time and the compressor wears out (and scraps the whole system as you can't get all the sludge out).

I suspect not using it and paying for a seasonal re-gas works out cheapest...

(Oh and don't think that the compressor on an EV is any better, because it can be sealed to eliminate the leak around the shaft- they aren't. Mine failed after 22,000 miles and 4 years, I can't estimate running hours (I'd guess at less than 2000 hours though) as I only owned it for two of those years but it was a heat pump and permanently running in use and when charging....)

I’ve redone my investigative steps, obviously apart from being able to check refrigerant/oil levels.

Here’s where I am:

- heater controls functioning as they should
- cabin filter (improved fitted) not blocked but could maybe do with replacing
- AC compressor engages and disengages as it should, all be it noisy
- High side gets hot, low side gets cool/could even be described as cold 
- No condensate from the drain
- Evap cleaner sprayed up via condensate drain, no change

Vehicle history:

- We are the 2nd owners - early 2019 reg vehicle currently on 45k miles
- AC is always on to ensure seal integrity/prevent clutch from seizing
- Has never been in a collision, AC rad appears in reasonable condition for age
- Serviced and maintained according to manfs schedules and specs.

As I have said, I am at a loss, all I can think to do is to remove the current compressor, have the system flushed, replace the compressor unit with a recon/new one and refill refrigerant and oil. 

I have never had an issue with an AC system prior to the JB74, and always run the system no matter the weather. Prior to it starting to give up about 6 months ago the AC ran well and was extremely cold, even in high heat. No idea what’s gone wrong!