I have Certified 2013 TL w/58k. It was originally a lease (leased through the same dealership) only had 26k, still had factory warranty left but I also purchased the extended (Thank God!) I bought the car at the end of the summer in 2016, AC worked great & I don’t remember having any issues that winter with the defrost either. Spring 2017, AC will only blow warm air. Took it to the dealer & found 2 leaking o rings, suction & discharge line o rings to compressor. After that the AC worked great rest of the season & no issues w/defrosting either. Spring 2018, AC runs for about 10min then starts blowing warm. It would blow warm for about 10-15min then kick back to ice cold for another few minutes. The longer it ran, the longer it would stay warm & the times when it would blow cold got shorter & shorter. Took it to the dealer. Found the discharge line o ring leaking (Again!? 1yr later!). Replaced the o ring... 4 days later the problem returns (ugh!) Take the car back to the dealer.. this time it’s a leak at the suction line o ring (AGAIN, 1yr later!!?!) They replaced the o ring & kept the car overnight to make sure the issue didn’t return. They told me they went through the whole system & found no issues with anything (fans, compressor, sensors, relays, etc.) Picked the car up in evening.. AC is working great!! THE NEXT DAY, I was about 10min into my drive home from work & BAM!! problem returns!?! My car goes back to the dealer yet again in 2 days. Has anyone ever had this issue before? Or have Any suggestions on what the issue might be? I’m starting to get desperate.. the temps are going to be close to 100 in the next few days

Following cause mine is doing the exact same thing.

I ended up having the a/c clutch & field coil assembly replaced & it has worked great since!