Duovalve question - PeachParts Mercedes-Benz Forum

rjk · #1 08-25-2013, 01:13 PM

I recently had a frozen compressor replaced.
I now have the dreaded left-side center vent blowing hot vs. Rt side cold.
Thoughts went to duovalve (I am assuming the tech charged the system properly).
I disassembled the valve and nothing stood out with one exception.
There is coolant in the coils.
Is this normal? Or is the rubber seal supposed to keep coolant out of the coils?
I have a few extra valves from the local pull-a-part.
I will do more extensive troubleshooting this PM when the car reappears.
I lean toward the duovalve vs. low coolant since at times, the system works fine. It seems to misbehave when it is hottest outside, natch.

silverteam · #2 08-30-2013, 04:41 PM

Why don't you pinch off the duovalve and see if the A/C is working fine? Yes if the freon is low on this model one side could be cold and the other side not as cold.

-Joey

dlssmith · #3 09-03-2013, 11:10 AM

It's low on freon, assuming this is the 99E320. Mine does this every spring. Very, very small leak, somewhere. Just enough to require a small charge and she's good to go for the summer. But the symptom is cool on one side, warm on the other.

rjk · #4 09-07-2013, 07:54 AM

I replaced the duovalve with a used unit with no change. It still misbehaves in hot conditions.
Curiously, when I set the fan on low speed before I engage the A/C and then slowly increase the fan speed, things seem to act normally. It is likely to misbehave when the fan is on high when I engage the A/C.
I'm going back to the shop that replaced the compressor today to have them check the charge.

rjk · #5 09-15-2013, 01:17 PM

The shop tested the system and found a low charge. It didn't require much and they put in what was necessary for free. I figured they had not gotten the correct charge when they replaced the compressor and the owner probably thought the same but he wondered if there was a leak somewhere. We shall see. Its working fine now.