Air conditioning not working

[LostKiwi]

Lots now use R744!

We are paying twice what we spent last year on R134!

Is 744 directly interchangeable with 134?

 

[alexanderfoti]

Is 744 directly interchangeable with 134?

No. It runs much higher pressures (its co2)

 

[Botus]

Lots now use R744!

We are paying twice what we spent last year on R134!

thank Alex, allowed me to find this
https://www.arcltd.org.au/media/1040/auto-gas-booklet.pdf


Is R1234yf compatible with existing R134a equipment?


No. The R1234yf system refrigerant circuit is accessed using service couplers that are a different size to those of a R134a system


Is R744 compatible with R134a equipment?


No. R744 operates on pressures up to ten times higher than R134a. Although it has been used for some time in stationary equipment, developing R744 systems for automotive applications has been a significant engineering challenge, with unique components and system layouts required for this refrigerant. R744 is pure carbon dioxide. the extremely high operating pressures of R744 and hazards associated with potentially high concentrations of carbon dioxide in vehicle cabins or working environments means this refrigerant must be used with care.

 

[RUBBER_UNDIES]

It's good to have with a Mercedes

 

[bc100]

Well to save time and the purchase of icarsoft etc, I went to my local independent Mercedes man and he said it just needed a re-gas. So £48 and half an hour later I drove away in a cool car.

 

[noonboots]

If the air con machine is used properly it will tell the operator if there are any leaks. To do it properly the system is emptied of gas and old oil, the gas amount is measured. Then the system should be left under vacuum for at least 15 minutes to check for leaks. If all is OK the correct amount of gas and new oil is put back in the system. If A/C systems need topping up they have a leak. A "top up" is a quick way of making it work and making a few quid for the garage.

 

[alexanderfoti]

If the air con machine is used properly it will tell the operator if there are any leaks. To do it properly the system is emptied of gas and old oil, the gas amount is measured. Then the system should be left under vacuum for at least 15 minutes to check for leaks. If all is OK the correct amount of gas and new oil is put back in the system. If A/C systems need topping up they have a leak. A "top up" is a quick way of making it work and making a few quid for the garage.

There is a natural amount of leakage but it's not annual. We have so many cars that pass the vac leak test that clearly have leaks. We have found nitrogen purge and soapy water a good one.

 

[LostKiwi]

The reason vacuum doesn't always show leaks is because vacuum can pull the seal tighter around the shaft of the compressor sealing it. Ditto any joins.
UV dye added to the refrigerant can be very effective at finding leaks.

 

[bc100]

Sadly the air-con stopped working again on my trip to London so I took it to an independent Merc garage in London and he said the condenser was leaking so £700 later I am once again cool.

The message here is that I should have realized that a recharge after only a year pointed towards a leak.

 

[pt-pro]

The reason vacuum doesn't always show leaks is because vacuum can pull the seal tighter around the shaft of the compressor sealing it. Ditto any joins.
UV dye added to the refrigerant can be very effective at finding leaks.

Additional reason is normally inside aircon system there is ovepressure (opposite for vacuum). IMO the best way is to fill aircon system with nitrogen with high pressure and then try to find leaking points (sometimes use water-soap and looking for bubbles)