AC System Help

[duracellttu]

I’ve been trying to track down issue with my AC not blowing cold air. I’ve taken it to the shop to get the refrigerant topped off twice now. The last time it blew cold for a while before the car sitting for over a year. Now it’s blowing room temp.

Is it safe to say I have a leak in the system since the pressure is so low? Trying to figure out if it’s a compressor issue or a busted line/seal. Any advice?

[George Hill]

If I was in your shoes I'd start by looking for a leak. The pressure sensors are incredible rare to fail while an evaporator is an incredible common source of leakage. Hopefully the last place to charge the system added UV dye, if so get a set of UV glasses and light and start looking at all the connections. BUT likely your issue is the evaporator and you won't be able to see the leak with the UV light. You'll need to pull the blower cover off and inspect either way though.

[duracellttu]

Thanks, I’ll plan to do that this weekend. I got a UV light the other day to check it out. I’m pretty sure the shop put in dye.

[Slideways]

If I was in your shoes I'd start by looking for a leak. The pressure sensors are incredible rare to fail while an evaporator is an incredible common source of leakage. Hopefully the last place to charge the system added UV dye, if so get a set of UV glasses and light and start looking at all the connections. BUT likely your issue is the evaporator and you won't be able to see the leak with the UV light. You'll need to pull the blower cover off and inspect either way though.

Does an A/C recharge typically hold on one of these cars if it has been over 10 or 20+ years since the system was last filled? I'm guessing they all develop a slow leak over time or it's not a perfectly sealed system from factory.

[George Hill]

Does an A/C recharge typically hold on one of these cars if it has been over 10 or 20+ years since the system was last filled? I'm guessing they all develop a slow leak over time or it's not a perfectly sealed system from factory.

BMW states there is an amount of refrigerant loss that is normal over time AND/OR if the system has not been in use for an extended period of time, IIRC they referred to it as "Seasonal Losses." I would imagine (for the most part) that no E46 with any kind of frequent use has made it this long on the original charge.

I evacuated my wife's E46T last night while doing some diagnostic work and it was 0.3lbs low, she likely has a small leak from the evaporator as I charged it last summer as 0.3# loss over a year is not "normal." It has been my experience that when the system has a legitimate hole in it there will be no refrigerant in it, BUT if it has a leak then it almost never gets below 0.3# in the system. I'm not explaining that well I think... if the car takes a rock to the condenser it will empty the system, but if the compressor seal or evaporator is leaking it seems they will always get down to a certain capacity and then just stop leaking (the system will not cool adequately at that charge level). I've also found E46s to cool "normally" with as little as 0.6# in the system (full is 1.63#).

[bigjae46]

If the evaporator was leaking and dye is injected, wouldn't you see the leak from the drain tube?

[George Hill]

If the evaporator was leaking and dye is injected, wouldn't you see the leak from the drain tube?

Not always.