Having issues with girlfriends 2007 Nissan Sentra 2.0L MR20DE engine. She's had the car for roughly a year now at about 129k miles. Her issue is that the AC will stop blowing cold air after some time, the amount of time will vary but usually will occur after roughly 20 minutes or more... At first I thought perhaps she did not have enough refrigerant in her car but I checked with one of the recharge kits and she had the proper amount of PSI going by the Haynes Sentra 2007-2012 repair guide. Anyway I couldn't figure out what the issue could be since it had the right amount of refrigerant on the low side and the AC compressor does come on. Took it to my mechanic and we found out that there was too much pressure on the high side. He used the machine to remove some to get it to the right psi for the high and low but eventually the ac would start to blow out warm air. We also noticed when that started to occur was due to the AC compressor cutting off. If we let the car settle / cool for a bit then the ac compressor would blow out cold air again until 20 or so minutes and back to warm air. We then decided to remove all of the refrigerant and add new/proper amount and same issue occurred ac cuts off after x amount of time and warm air comes out. We came to a conclusion that maybe the AC pressure switch was throwing off some flag to force the AC Compressor to cut off. We got a new ac pressure switch removed refrigerant replaced the switch put new refrigerant in and same issue... Essentially that's where we are stuck at right now. We are stumped because at least what we can tell with this AC system in this sentra it is a very simplified system. We don't believe the issue is with the ac compressor because it does work for 20 - 30 minutes or so before it cuts off. Another mechanic that I spoke with believes it may have something to do with the accumulator. That perhaps dye, old refrigerant or something may have hardened/settled in there and it takes a bit of time when the AC is on for the settled stuff to lift and possibly clog the accumulator thus increasing the pressure and causing the ac pressure switch to shut the ac compressor off? He indicates may need to take the compressor off and try to clear/clean out the accumulator since it is a vertical piece on the bottom of the car and possibly something is settled in there.
Sorry for the rant guys any help or advice would be appreciated. I will summarize what was done below.
Issue: AC Compressor cuts off/blows warm air after about 20 or so minutes.
Tried: AC has no leaks, was over pressure and corrected the pressure. Removed refrigerant completely and added new refrigerant. Replaced AC pressure switch.