Howdy folks- I just rebuild the entire a/c system on my 1983 300D.

New CompressorWorks compressor, dryer, Expansion valve, all hoses and evaporator flushed, parallel-flow condenser installed with custom hoses.

PAG-150 with dye, 30 oz of R-134A.

Cleaned evaporator w/foaming spray.

I have cold air (51 at idle/vent, 90 degree ambient outside) from the right center vent (center vents propped open) and the right passenger vent.

Coldish air (61) from left center vent, and then warmish air (82) from driver's vent.

Fan on high, makes a lots of rushing noise but doesn't seem very powerful.

I have the heater core blocked off b/c the heat is trying to come on, even after repairing the monovalve).

Going down the highway I can get low 30s on the right vents but with the weak stream of air and the warming from the driver's side, it's not cutting it.

Any ideas here?

It makes no sense to me either, the center vents share a common plenum for crying out loud!

__________________
~Sugi
1983 300DT
1964 Triumph TR4 (back in the stable after 18 years- same car!)
2004 Pontiac Vibe
1986 Honda Elite CH250
1971 F100

First lets be sure we are on the same page on the blower speed..
is yours on LOW ?
and you have a pencil thermometer sticking in the center vent?

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Sounds like you didn't block of the left side heater core.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Thanks for the tips.

I went out and put a 3/4" pex brass ball valve from Lowe's on the return side (right above the oil filter housing).

This stopped all flow and fixed the vents' unevenness.

Now I just have to test my blower motor to see if I can get more volume out of it.

When I cleaned the evaporator with foaming spray, it did not seem very dirty on the surface (checked by swiping my fingers across it via the hole after dropping the blower motor).

I'll see if I am getting 12 volts there.

The fan seems to spin very smoothly so I doubt it's the bearings.

Great!! Check and make sure that the foam hose that goes to the ACC temp sensor on top of the dash has not fallen off from age.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Do you mean mechanically blocked off the heater core by clamping the hose, or doing something to the air stream?

Check your driver's vent tube is actually connected up snug to the plenum and the vent. Weak flow and high temps would seem to indicate an air leak that lets the cooled air go somewhere under the dash and you're measuring ambient-ish at the vent, not cooled and flowed-there via ducts.

The tube could easily have been detached in a cluster repair, speaker swap, or something.

For the monovalve you could try electronically closing the monovalve by providing an alternate path to ground since the CCU switches ground with steady +12 from fuse 14. Use a meter and get your wires right so you don't blow the CCU.

You could check electrical connections from the battery all the way through fuse 14 to the valve make sure the +12 is steady and clean.