typhoon43

Hot as satan's sack today so cranked both the left and right side to LO and Max Cool. Both settings on the location dial were the same, but the passenger side center vent was noticeably cooler than the driver's center and driver door. Maybe a stuck vacuum actuator on the blend door, or a dying thermocouple on that side? I wouldn't mind if I had a right hand drive model
Anyone else ever experienced this?

stockC43

Sounds like its low on charge. Evaporator is closer to the passenger side and by the time the cool air gets all the way to the drivers side it warms up. The AC system usally will hiss when turning on and off if its low on charge. If you hear this as well, its a safe bet you need a AC charge.

E55Greasemonkey

This ^^^

If your 2 center vents are different temps, that typically means you are low on freon.

allenjdmb

That's usually right on most benz cars....+1.

typhoon43

Awesome guys. I'm making a small list of things to have an Indy check out since I've only had the car for a few months, and want some changes made in STAR. I'm assuming these cars are a little more complicated than me plugging in a Pep Boys "Cool in a Can" setup and squeezing some R-134 in.

stockC43

If you do add a can make sure it's plain r134. No oil or leak fix etc. I would say for the $10 why not. At the very least you'll be cool untill your Indy looks at it. If you want it perfect though you need a set of proper AC gauges and leak detection dye would be a good idea.

211.076

Sounds like a duo valve to me. Fairly common occurrence on the 211's. Typically if it was low on refrigerant, it wouldn't blow as cold, but still the same temperature throughout the car. The refrigerant has no way of dictating where it is going in the system, or which vents will blow colder than the others.

pihrana

I have the EXACT same issue on my 05 E55. I have not taken it into the dealer yet as I would prefer to have a go myself if I knew what to replace. I tend to agree with 211.076 that it is not a refrigerant issue as we do have cold air for the passenger side zones.. (Although it would be an easy fix if it was, and is a relatively cheap thing to do and rule out)

Either way, I'll be keeping an eye on this thread and will update all with any options I try.

211.076

The duo valve is located beneath the wiper cowl. Not hard to change out. If you wanted to test it first, you could gain access to the duo valve, and tap it with a small hammer to try and release the valves on the inside. This wont always work, but if it does then its an easy way to diagnose the problem. I would be willing to bet that its the duo valve though, given the symptoms you exhibit, as well as my time working with mercedes benz and seeing this problem numerous times, most prominently on 211's.

Also, keep in mind that if the refrigerant level is ok, and you just start arbitrarily adding refrigerant you could cause damage to the system.

cij911

^^ Very true....Also mechanically it does not make sense that one side would be cold and another warm and the root cause be coolant level....

211.076 appears to have the logical answer on this one...

TECHNICIAN

Freon

pnoyworx

Doubt its freon. Do you have the same amount of air blowing on each vent? Low on freon would mean you have a leak since our AC is a closed system. Also if you have cold air in one vent, it would not warm up that quick that it would be warm enough on the other vent. My guess is a blending valve or an actuator.

brendakearney77

The duo valve is located beneath the wiper cowl.

brhams27

I have the same problem on my w211 220cdi ! the air blow is the same on the both side,but in the left side is not so cold like in the right side ! what is the problem: Freon ? Duo valve ? Actuator (what is this?) Thanks in advance!