91Q AC dead - help

[yidal88]

was low on charge , AC worked but very weak . My long time mechanic evacuated , charged it to the correct weight , checked everything , took it for a test drive , even sticking termometer in the vent . came back said everything is good - working fine . I get in the car driving off - AC blowing hot air . Just 5 minutes before worked fine ??? . Came back , they evacuated , charged 5-6 times , looked at everything - nothing , blowing hot air . The compressor is engaging , clutch seems OK . I think he said 'low pressure reading high' or something . Is it expansion valve or dryer ? Any ideas ?

[benemorius]

Why can't the mechanic diagnose the problem?

[maxnix]

No mention of drier replacement? Can't be properly recharged without a new one. Any leak tests performed?

[Aussie Q45a]

What Code do you get from the self diagnosis?

[Jesda]

Is the high/low pressure switch defective?

[qship96]

No mention of drier replacement? Can't be properly recharged without a new one. Any leak tests performed?

complete nonsense! DRYER does NOT need to be replaced to evac-recharge system.

[benemorius]

complete nonsense! DRYER does NOT need to be replaced to evac-recharge system.

If you bring a car to me with a low charge or in an otherwise questionable condition, hell yes it does. When you don't know, you replace it.

[Q451990]

I would say that it needs to be replaced whenever the system is opened. For a simple evac/recharge without unbolting anything - I would say a long vacuum and recharge would be fine...

Heath

[benemorius]

Agreed, BUT since you don't always know what has or hasn't happened to the system, you have to play it safe. For me, playing it safe means replacing the dryer any time I suspect even a slight chance that the system may not have been properly worked on. Low refrigerant is reason enough for me. For all I know, all the refrigerant leaked out and the system was recharged with one of those cursed interdynamics kits before leaking a bit more.

[yidal88]

Well , we did the long evac before recharge few times , but did not help . still just blowing outside air in. What could have gone wrong in 5 minutes though? I'll try getting the self diagnosis code . still weird

[maxnix]

I would say that it needs to be replaced whenever the system is opened. Heath

Yes, and also if it is aged as its function is to trap any moisture in the system.

[maxnix]

Agreed, BUT since you don't always know what has or hasn't happened to the system, you have to play it safe. For me, playing it safe means replacing the dryer any time I suspect even a slight chance that the system may not have been properly worked on. Low refrigerant is reason enough for me. For all I know, all the refrigerant leaked out and the system was recharged with one of those cursed interdynamics kits before leaking a bit more.

Leaking is always an indication of contamination from air. Pressures will equalize.