AndyRKett probably built that video
Seems likely....
Firstly though
by both flicking the Schrader valve on the low pressure side of the system and checking the readouts on ECUscan, I established that there is still some pressure in the system
NO!!! Never EVER !! do this, aside from the fact it is technically (and actually) illegal. It is also extremely dangerous and can if done incorrectly result in a gas embolism which can be fatal. Also R1234yf is flammable so you can end up with a nasty fire. You knew the clutch wasn't kicking in and you had
MES to tell you how low the pressure was, this would have been sufficient to identify the problem. You can also scratch the ball in the valve and cause a leak from the valve resulting in a leak where there wasn't one and need to replace expensive pipework.
You can turn the pump by hand with the engine off and check on
MES to see if the reading on
MES changes, even if its only a few mb then its enough to know there is still some pressure in the system (i,e no big hole anywhere and the sensor is not 100% accurate)
So what to do.
If your car has R1234yf then you are indeed looking at a more expensive bill. however normal proceedure to "regas" the sytem is to suck out all the gas and any air, then hold the system at a vacuum for about 30 minutes. If after 30 mins there is no loss of vaccum then the system is usually deemed to be sealed. So you pump in the gas, a bit of oil and maybe some dye, then do a "sniff" test with a probe that can detect the gas if it is leaking out. This is all par for the course and is not some highly expensive fault finding proceedure.
So what you do is just book it in for a regas if they gas it and give the car back then all is good.
If you don't get it done the pump will usually, eventually seize up, like an engine that is left for years unused.
The seals in the rest of the systems will degrade and leaks will be enevitable rather than a maybe.
and to be honest if the car is just our of warantee i'm assuming it's 3 years old or older, and its probably just about due a regas, its highly unlikely that a standard regas would be covered under warranty, especially if its a fiat warranty as they are tight as a ducks......
You may need to phone around to find a garage that does R1234YF but it is worth doing, and is best to look for a quality independent aircon specialist rather than pay main dealer prices.
My final word is that if you choose not to get it done, then remove the pollen filter otherwise the filter will trap moisture which the aircon would normally remove from the air, the car will become foisty and mold can develop, if not on the car interior, on the filter which then gets blasted into your face by the cabin fan.
You can get top up sets for R1234yf but you need to be topping it up before it stops working, once it has stopped working then the pressure has dropped to far to say if system has just lost efficiency because of low gas, or if its because of a leak, as an explanation to this. The gas might leak out at 12 bar, but the pressure drops to 1.2 bar and the gas can no longer push its way out past a weak seal.