KM97

Hi all, just picked up my new A4 and I'm struggling to figure out how to switch on the air con, it comes on automatically when the ignition is on but once the car has started up it turns of and I cannot put it back on? And help is greatly appreciated.

crystalmountainskier

I had this happen with my brand new 2018 and it ended up being a major warranty repair.

https://audiworld.com/forums/a4-allr...c-off-2946198/

I can give you the specifics of what they replaced when I get home tonight.

KM97

Oh great that's not such good news, yeah if you could let me know that would be great.

crystalmountainskier

Here's the service writeup:

Verified AC will not turn on. Found fault in AC system for B10AE21" High Pressure sensor lower limit not reached static. Inspected AC system and found no signs of damage or leaking at this time. Found low refrigerant pressure at 0.8 bar. Read MVB and found last compressor shut off stage due to low refrigerant pressure. Evacuated AC and found no refrigerant present. Performed vacuum test and found system holds proper vacuum and no leaks were found. Recharged AC with 525G refrigerant of 1234YF. Tested AC and found pressure now at 10+ bar under max AC. AC is operating properly at this time, like similar known good vehicle. Ordered shop tool to add dye to system. Injected dye and found condenser is leaking. No signs of outside influence. Evacuated refrigerant. Removed front bumper cover. Replaced condenser with new seals. Swapped over AC pressor sensor. Installed bumper. Performed vacuum test and recharged AC with 525G regrigerant (1234YF). Verified no leaks. Tested AC and found AC is operating like similar known good vehicle at this time.

This all took about 15 days to get done. So far, no problems since.

lowjdml

In terms of the basics, I assume you are lifting up on the "A/C OFF" switch once or twice to get to A/C ON and A/C MAX mode?

KM97

yes, I've tried that more than once.

breadbooze

Low refrigerant. AC might show ON but until the engine cranks and spins the compressor there isn't any refrigerant circulating. With low refrigerant the AC compressor will disengage the clutch to save itself and prevent the climate control from turning the AC on.

Ayanami

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