I'm still confused.

You said that it sometimes goes days or weeks and works just fine, then for no apparent reason it stops blowing cold. You also said that it always works when driving and only stops working after the car has been sitting. I assume that the car sits sometimes during the days/weeks that it keeps working, yes?

Are you recharging the system every time in order to get it working again or is there something else that you're doing to get it to blow cold again? Do you have pressure gauges to measure how much refrigerant you're adding?

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Robert Fini

'12 ML350 BlueTec, 87k
'06 E320CDI, 270k
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 69k
'97 C36AMG, 313k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)