I flushed everything with an aerosol flush from the auto parts store and followed that up with compressed air. I used a 1.5CFM vacuum pump (not the venturi type, 110V piston powered) and ran it on the system for about an hour. I am using mineral oil designed for R12 systems with no additives or dye. I installed approximately 8OZ and you can subtract an ounce or less after removing some refrigerant today. It is possible that there could be moisture in the system but then anything is possible.

Listen to the radio as I get in the car. Giggidy.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

That sounds like the right procedure to me. How long did you blow the flush out of the evaporator and how did you blow it out (specifically)? This is probably the most common place moisture gets trapped. Sometimes it works to "plug" the exit hose which the air is coming out to build back pressure. This increases the velocity or the air when "unplugged" and take some moisture with it each time. I accomplish this by using my thumb to plug the hose/tube.

But of course if this were your issue, then you would need to take the refrigerant out and do the whole procedure over which may not be worth it to you. I guess it is really up to you as far as the route you want to take. You could either keep exploring air flow issues, live with it as is, or try it all over again and maybe get better results, maybe not.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

I did exactly as you mention. After getting the majority of the flush out of the evaporator, I let it build up pressure with compressed air then I released my finger from the other port and more flush came out. I did this until I got just a drop or two. I did the same thing with the condenser.

This morning it was 83OAT and I got 50F at the center vent with the fan on low. I'm still stuck at a 30F delta. I'll try messing with the recirc flap and completely shut it off.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Another thought that I don't think has been mentioned is a blocked evaporator. Unfortunately it is hard to get to. I think Dean Morrison has a thread on here about how he cleaned his. I believe his username is dmorrison.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

A couple weeks ago before I went back to R12 from R134a, I took the evap fan off, sprayed some coil cleaner in there and blew the crap out of it through the opening for about 5 minutes. I used the pressure washer at the car wash to blow it out. Yes, I set it to rinse and not wax.

I don't know what I did wrong in this project but something has to be keeping my temp delta at about 30F. It could be 105F or 80F out, I still get a 30F delta.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

A constant delta T relative to outside temperature sounds like you are drawing 100% fresh air because the recirc flap is not closing. The AC removes a more or less constant number of BTUs from the air stream flowing over it, which in turn will lower the temperature of that air stream by a consistent number of degrees, with some variability due to humidity.

You sprayed a pressure washer in the interior of your car?

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cbjukraine
'84 300D

Yep. I shoved it in behind the evaporator and blew the sheiss out of it for 5 minutes. At least I know the drains work real well. The interior didn't get near as wet as you would think. Once the nozzle is in the evaporator box, the water drains out. There was some mist coming out of the vents but no big deal. This is Texas; it is so hot here, I could pressure wash the seats and they would be dry in 2 hours.

Oh, I am going to check the blend door again. This time I will remove the glove box and find a way to wire it shut.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Shouldn't need to wire it shut. The default position when the car is off is closed, meaning no outside air. Just unplug the line to the vacuum pod and cap it off (the line, so you don't create a vacuum leak). Keep in mind that the foam MB used around the edges of the fresh air flap has probably long since disintegrated, so some amount of fresh (hot) outside air is always going to get in.

Doing this however, will mean that you can't effectively use the "EC" setting on the climate control. The blower motor will spin in vain and not blow any air.

A better way to do this is hook up a 3-way vacuum splitter to the #4 switchover valve, and connect both the recirculating pod and the fresh air pod to #4. This will give you no fresh air in A/C mode, and all fresh air in "EC" mode.

An even better way to do it is wire a switch that gives you control of the fresh air flap. I used a switch from an early 80's 190D.

Attached Thumbnails

   

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cbjukraine
'84 300D

OK, here are some videos of the recirc flap trouble shooting. I eventually made a stick of wood to shove behind the recirc door to disable any outside air for testing purposes. My phone ran out of memory before I could record that modification. OAT during testing was 100F. I went for a highway-speed test drive and I got a low of about 50-52F with the blend door 100% closed. I opened the windows all the way with the A/C on high and it went down to 60-62F at vent and stayed there at highway speeds.

300SD AC recirc diagnosis part 1 - YouTube

300SD AC recirc diagnosis part 2 - YouTube

300SD AC recirc diagnosis part 3 - YouTube

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Oh man, forget everything I said. I didn't know the 126 SD system was so radically different from the 123 D sytem...

__________________
cbjukraine
'84 300D

If it isn't one thing, it's another! I disassembled, cleaned, and greased the upgraded 15" fan I got from the junk yard. After installing it, it seems like the motor is bad. It spins fast when cold but slows down after a while. I touched the nut that holds the fan blade assembly and it was very hot. The motor was full of dirt and road debris and the front bearing was seized. I freed it up but I think it's just FUBAR now. Time to drop another $100 into this car for a new fan assembly.

Previously, I wedged a wood dowel in to keep the recirc flap 100% closed and I got about a 4F temp drop at highway speeds.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

One thing to note: You need to swap the terminals on the new fan before you connect it. By default it blows air away from the condenser toward the front of the car. My old fan blew the air into the condenser so I figured so should this one. Idle temps are better but I still cannot break a 30F delta. I see bubbles in the sight glass, so I will add some R12 slowly until the bubbles go away. I'll also check my pressures again at 1500RPM this time.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

What is an evaporator fan? Are you talking about the evaporator or the condenser? I was referring to the evaporator in the dash assembly. I guess you could be talking about the blower motor but it almost sounds as if you are talking about the auxiliary fan on the condenser.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

I just returned a new Behr compressor...the holes were tapped wrong - made attaching the bolts to the frame difficult, and the 15mm manifold bolt was tapped at an angle!

cost me a drier and a lot of sweat!

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT