Need some diagnostic help re: my intermittent A/C problem. It runs COLD one time, then next startup -- no COLDA/C, etc etc. (Note: there never has been a BLOWER problem per se -- of any kind.)

Today the air (1) came on cold in the AM; I turned off the A/C when parking.

(2) The next startup a few hours later, no cold air -- just the blower putting out warm ambient air in effect, but the COMPRESSOR WAS ON -- just did not produce cold air in the car (again blower producing warm air - not heater level hot air at all.) Turned off the A/C when parking again.

(3) The next startup, one hour later --- the compressor came on and the cold air developed normally ..... no problems of any kind.

It appears that some control flap or sensor or valve is operating erratically, even tho' the compressor/blower systems are operating.

Can anyone ID the probable cause for this kind of erratic action, where the
compressor comes on and produces COLD one time; compressor comes on and the blower system just pushes warm air in the car the next time???

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)