Hot & Cold Air At Same Time

[ajcrowe]

My "new" 1994 C280 ACC system blows hot air out the side vents and cold air out the center vents at the same time. The heat works great now, but if you try to get some AC it will blow cold air out the center vents but continue to blow hot out the side vents. Any thougths as to the problem?

[Zewerr]

I have seen when the A/C system is only partially charged, it'll discharge different temperatures at different vents. But if you set it to max A/C, It would usually blow cold out of some vents, but only cool out of the others. Never was the air hot. Perhaps you could have a bad vacuum actuator. I don't really see a bad mono valve causing this problem, but I have seen them do some weird stuff periodically.

[PHAEDRUS242]

I'd go after the mono valve insert.

[KRK]

I had a similar problem with air from one of the centre vent coming hot and the other coming cold.

The problem was resolved once the duo valve ( also called heater valve) was replaced.

with regards,
ravikumar