So, 84 w123, had A/C off for a year and a half(who knows how long before that because that's how I bought it) because bad compressor clutch. I replaced the compressor and did an evacuation and everything held for 4 months. Too lazy to charge the system.

I finally charged the system. 1st day the cold air goes away on a 40 mile highway trip. Then it works after 3 days of no running but is not cold unless over 60mph.

So then I stop bothering with the A/C because I assume I have other issues. And at the time is seldom cold at any speed. Then, I started running the system anyway last week. Now, after 4 days of running effort non stop, I get cool air in 10 seconds after start and at idle, and cold air (as in enough to hit the low switch) after 5 minutes of driving at any speed.

Please! someone esplane!

Chunk-O-Crud blew through the expansion valve?

Another obstruction that killed efficiency?

Should we recommend beatification?

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

Ha ha ha, expansion valve was my guess and my friend's guess. (who is a very impressive mechanic)

The only other thing he could think up is that old oil in the system had gummed up somewhere and needed a lot of effort to move on. But he said that with a puzzled look.

I am guessing I ought to discharge the system, clean some stuff up, and recharge just to be on the safe side. But... after another 500 miles.

... you left the system evacuated for 4 MONTHS!
your dryer is shot, and you have contaminated oil causing havoc with your expansion valve. moisture is present in ice crystal form causing problems in the system.
remove refrigerant
flush with nitrogen
I would also flush all coils and lines and replace the oil in the system... but that's me.
replace dryer
pressurize with nitrogen and verify leak free.
dump nitrogen, and evacuate system, then immediately weigh in correct volume of refrigerant for your car.
all will be happy.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

will do