I've gone through my air conditioning system completely and went back to R12.
Put in a nice parallel flow condenser which especially works great in bumper to bumper traffic. My compressor cycles but the temperature at the vents never goes lower than 52 to 54° regardless of the outside temperature.

I've read on this forum how you can adjust the Evaporator Temperature Regulator by taking it out and putting the capillary tube in ice water turning the screw that adjusts tension on the 'big spring' etc

What I have not been able to find out is which way do you turn the screw to make the evaporator 'colder'.
Clockwise for more tension on the spring or loosen it?
I'd rather make the adjustment without removing the entire thing and using the ice bath.

Set the etr by pressures. Connect gauges read pressures/temp.
Engine running 2500rpm.
Low side pressure Said to be not below 25 lbs, if water in system could freeze expansion
valve,or if much moisture in air could freeze evaporator.
What I have seen,low side 12 lbs high side 175lbs, center vents 36 degrees,90 degrees out side temps.I"m I to tell owner it needs to be repaired, NO way! Only to say a/c getting a little to cold,If you have problems let me know. NO problems.
Are your out side air vents closed,If has.

If that is the peanut shaped one (etr), with the large spring inside, turn in to lower temp.
That would be clock wise. Some adj. nuts are narrow and will fall off end of threads if turned to far, just can not turn any farther.

Thanks Hercules,
I'll give it a half turn in & see what happens with center vent temps.
I put in 42 oz of R12 and the pressures/temps match the chart in the climate control FSM, including the air outlet temps. I want to make air outlet temps a little colder without icing up the evaporator. It seems that the ETR setting is conservative. Don't know if that is standard or due to being aged from 1983.

The factory setting was only slightly above freezing. They get wonky with age.

__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

@Hercules :

In post # 2 you say not below 25# low side but then say low side 12# gives 36* F vent temps....

My '82 240D has the SANDEN compressor and parallel flow condenser , when it's 80* F outside I get 40* F out the vents, the rest of the time it hovers closer to 55* F and I'm wondering if I should bleed off some of the freon ? .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

It did on that car, have even seen a low side of 8 lbs.and still working good.
You do have a sight glass,could use that if no air in system.
I have tried varying amount for best performance,helped some times.
No specific temp can I Quote,only for that car.
The outside air vents need to be shut,recycle air.

Remember I"am talking about R-12 systems.
The etr valves on these 123s The sensor tube part can get lazy.
When car inside temps are hot, valve is more open,when insides temps cool , valve closes
more, can get to where valve moves less.

Sorry guys! Had to get the cobb webs out. The etr controls the compressor cut in and out.
Have set many to 38degrees. No gauges required!!
All other Info. was about the expansion valve and pressures.
Many can be set lower.

Thank you for sharing your thoughts and experience .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I turned in the screw (clockwise-tighten) controlling the big spring under the plastic cover 1/2 turn, no change, vent temps still 52-54°F. Turned in another 1/2 turn, no change. Compressor cycles. I'll get a new ETR and see what happens.
I did remove the ETR last week and it was very difficult to reinstall. Capillary tube did not want to go back down the hole into the evaporator. Had to remove the blower motor and put a light behind the evaporator to see the hole and line up. That's why I've been adjusting it in place.

Without seeing your car in person, you most likely either have air in your system or improper refrigerant charge due to some unlicensed, untrained amateur / hack mechanic recharging of the system. Those "recycle" machines that a lot of shops use to recharge customers cars often are contaminated. Because if they suck in air from one customer's car, and then recharge it into another customer's car, then it is like an STD that keeps on giving. This is why I only charge from virgin 30 lb jugs.

Messing around with the ETR is not going to solve your problems !

In over 10 years of running a shop, I have NEVER....NOT ONCE needed to mess with an ETR.

I am not going to attempt to further diagnose your system online, especially for free.....but I have filled numerous cars with R12 and R134a. I currently have two 30 lb jugs of of virgin, r12 and I charge way more for it than you can buy the 14 ounce jackoff cans on ebay simply because with my r12 you get my expertise and equipment and diagnostic skills.

What you need to find (and pay for) is a local automotive a/c specialist, preferably an old-timer. If you are in Manhattan, then I can highly recommend Harvey and crew at Sports & Classics on the upper east side of Manhattan. I am not sure if they still have r12 but it is worth asking.

I have replaced a few of these, cycled to soon and would not adjust. Still had to set new
the new one.
Alex E, I misunderstood,Was thinking about the expansion valve,In-out don"t remember?
Sorry. Usually this many yrs. old is bad. If I remember correct the etr switch has two
adjustment screws one compressor cut out,the other cut in. Good luck.

Replacing my ETR certainly solved my problem. No doubt about it. (1982 W123.)

But I did have way more that 10 years of experience when I first encountered that issue, so maybe you just need a little more time in the field to get your feet wet.

While we are on the subject, there are two items (other than the OFF switch) on a W123 that will cause the compressor to cycle off. Do you know what they are?

__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Thanks upod for info on sports & classics, I'll check them out.
I don't have air in my system. I vacuumed for two hours and I installed from my 30 lb can of Dupont R12 42 ounces by the scale. I've been working on cars more than 50 years. My brother is an ASE Master Mechanic in all categories for 40 years. All components of the climate control are new or rebuilt. I had James Dean do up the push button control, silver box, and black box blower control. Looks like the ETR is the problem of vent temps not so great. Vent temps match what is called for in the factory climate control service manual, I just want them colder as people have reported achieving. I'll put in a new one and adjust from there.