I am new to this forum so forgive me if I am posting to the wrong section. I recently bought a 1995 E320, 154000 miles. I'm very excited and for the most part I am impressed with how solid the car feels.

I have A/C issues. I am getting hot air and cold air at the same time. The temperature wheel is set to the coldest position, the fan is set to maximum speed (top button).
I'll start with the option buttons from left(defrost) to right (off)
1) If i select the defrost button, all other vents are closed except the defrost vents. nothing but hot air comes out in the defrost vents - although it never gets scorching hot - its still hot nonetheless
2) If I select the next option with solid white arrows pointing up and down - i believe this option opens all vents - all vents do open. I get COLD air in the center console, hot air in the defrost vents, hot air in the side vents and hot air in the foot vents, hot air in the rear vents
3) If I select the third button - solid white arrow pointing down and clear arrow pointing up, center vent stays open and all other vents close. However, the air coming out of the center vent is mixed cold and hot. If I move my hand across the vent, i get portions of purely cold air and then i move on and portions of purely hot air - as if cold and hot air is being sent to the center vent.
4) If I select the fourth option, all vents open and i get hot air in all vents
5) If i change the temperature to hottest temp, i get all hot air in all vents - depending on which options are selected - however its all hot air.

I have had the vacuum valve unit next to the glove compartment checked and it got a clean bill of health.
i have had the freon checked and it is fully charged. I have figured out that the vacuums for the center, foot wells, side vents and defrost all work because they open and close variously depending on which option is selected.

I cannot figure out why i get mixed cold and hot air - can someone help me to figure out why i still get hot air even when I have coldest selection on temperature wheel. I have tried switching the recirculation on and off and there is no difference.
I have looked at the DIYs of removing the dash and consoles and they are very useful - however, I want to try to figure out what is wrong before I plunge into removing the dash.

thanks

Check the duo-valve(ELECTRIC HEATER VALVE), pinch the hose shut and see if cold air comes out measure with temp gauge , sounds like you have 2 problems, low freon and valve malfunctining

thanks Nulu

1) where is the duovalve? ..as in location in the system. i bought a manual by Motorbooks - it has a single page on the heating system and doesnt show much detail.
2) I had a garage check the freon and they said the freon didn't need recharging. when all vents are open, the center vent brings out purely cold air (fridge cold)

Usually on the right side in engine bay. Two vertical metal cylinders about 3/4" in diameter and side by side. When one is sticking you get differing temperatures out of the left and right sides of the CC unit. Sometimes just a tap on the top with the handle of a screwdriver is a enough to release it. If not, try opening and cleaning or replacing. Most sites have a DIY since it's a common problem. Especially in cars where the coolant isn't being changed regularly.

DUOVALVE!

bought new duovalve from Merc dealership $330. ouch!. replaced duovalve in about 45 minutes. started the car and felt cold air all around. problem solved. thanks to everyone who contributed to this thread.

I had to top up the coolant after the duovalve replacement - but i couldnt find a purge nipple to bleed the system. engine coolant temperature is flactuating between 90 and 100 degrees - so i suspect that there are some air pockets. Does anyone know how to bleed the system or can someone reply with a link to a good diy article. i tried searching but i am getting conflicting info - some claim the system is self bleeding, some claim that there is bleed nipple somewhere. the manual that i bought does not discuss bleeding the system.

Good job guys , my car 94 e320 did something similiar, so its good to hear ya fixed it. my wife drives tha car and she didnt notice heat coming out of right side vent and kinda warm/cold like yours.