I'm running the stock condenser with R12 and saw only about 48 degrees at the vent today on the freeway @60 mph. I stuck my digital thermometer out the window and measured 92 degrees ambient.

I just checked the pressures:

@ idle (with aux fan on)
high side: ~225 psi
low side: fluctuating between 45 and 55 psi

revving to ~2000 RPM
high side: doesn't go higher than 250 psi
low side: doesn't go lower than 30 psi

I've also leak checked the whole system with a halogen sniffer and go no alarms. Any help is greatly appreciated. I want ice cubes blowing out of the vents! This is very confusing, as two summers ago I had a stock working system with R12 and was regularly getting 36 degrees in high 90s Texas heat.

I'm referring to the car in my signature...

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cbjukraine
'84 300D

Pretty sure the sanden works better with 134A

You got anything to back up that statement? Compressor doesn't care what it's pumping. ...only the efficiency of the feon/propane/R12/134a or any other medium has anything to do with vent temperature in any given environment.

If there is leak of coolant heated air into the evaporator housing, or the evap' is partially clogged due to internal corrosion etc etc ...causes temperature changes.

Never found a factory fitted a/c to a 123 that performed flawlessly every season and I have serviced around 200 of 'em.

If you live in a state that allows non SNAP 'freon' you can get vent temp's in 108 degree ambient temp's in the 30's depending on blower/engine speed .

Internal corrosion is often the cause of changing performance from one season to another. Design of condenser helps efficiency as does different 'freons'. Common causes of higher than usual vent temp's is recirculation or blend door not closing.

On a Vanagon, the Sandon SD5 or 7 is about as good as a chocolate tea pot to cool the van in any temp's above 80 F....try 134a in that and see if it helps !

I'm always hearing different theories as to why thing don't work as they think they should from folk who have no experience in anything other than the vehicle they own as the gold standard for all others.


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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

OP might need a new ETR or adjust his ETR then.

It is possible the TXV is opening at a higher temp reading but that is easily checked. Observing the CC will give you an idea if it's causing the CC to deactivate too early or too often..it's possible the TXV is bad or out of calibration.

A TXV is calibrated differently to R12 as opposed to 134a.


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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I'm 99% sure the compressor isn't cycling on the road, so that would lead me to believe the ETR is working properly. What are they set to from the factory, 'cause I've never touched mine?

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cbjukraine
'84 300D

R12 TXV is usually opening around 36F although i measured a few at 31F (?)
I have not measured a TXV set for 134a as they where all new in the box...all TXV's are now set for 134a.

They are really to stop the evap' core from freezing and from freezing the heater core too. I had a vehicle that actually busted two heater cores in a few months. Turns out the TXV was never turning off the CC and it froze the condensate and then the coolant in the heater core....because the owner...who will remain nameless...said he had antifreeze free at work and would add it later....but never did. I never let a vehicle leave now without antifreeze in the coolant at at least 50% mix. Ho hum...ain't life grand?

BTW...they seem to all close again at 42F.



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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Are we talking about the ETR (Evaporator Temp Regulator) or the TXV (Thermal Expansion Valve)?

I was referring to the ETR working because the Evaporator isn't getting cold enough for the ETR to open and cycle the compressor, as I'm not feeling the engine shudder at all on the road from the compressor kicking in.

But my TXV may not be letting enough liquid refrigerant into the evaporator either...

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cbjukraine
'84 300D

Run following test:

Place vehicle out of the sun. A/C temp' at MAX .... blower speed low. ( Recirc' door closed.) Close all windows and doors. Insert temp' probe in center vents. Run engine at 1800 rpm. After some time temp should drop to 34F to 36F and CC then disengages and vent reading should climb to 38 F or 44 F and CC should engage and vent temp' drop to 34F to 36F again.

If Yes...system working as designed.

If No....Check if system over pressurized and pressure switch cutting CC...( If fitted and operational.)

Check blend doors are fully in Cooling position. Check Recirc' door fully closed.
Check cabin temp' sensor ( Ducted air into center dash small grill.')
Check belt slip at CC.
Check CC slip ( Check voltage and air gap.)

On your figures..Ii would prefer to see lower low side pressures. Minimum 20 psi but lower than 30psi.

Are you using a parallel flow condenser or OE original ?
Does aux fan run whilst CC engaged?

What Sandon are you running? Japanese or Chinese copy?


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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Jumper the ETR with a fuse or something and retest. Don't do it for too long so you don't freeze the evap.

As the 123 doesn't have a recirc button, how do you know when it goes into recirc?

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I never go far without a little Big Star

1994 E500 199/Gray 82k
84 300D (Salty) Orient Red/Palomino 141k
88 300CE (Ersatzhammer) 904/Java 163k -- Turbo Technics twin turbo kit, AMG Gen I body kit, Sportline steering box and steering wheel, Sportline/Eibach /Bilstein Sport/500E suspension, Quaife LSD in 210 mm diff case, Silver Arrow brakes.
88 300CE Brabus 3.6 199 on Black 44k

Try these two links:

Rerouting vacuum lines to have recirculated a/c at all times?

w123 recirculation "flap"

The text describing which of the 5 electric vacuum valves to select somehow got cut from the first post. But that information appears in the 2nd thread linked above. I deny any relationship with the guy that wrote the original article.

IIRC, the CCU decides whether to invoke recirc based on the temperature delta between the setpoint and the vehicle interior. On a 123 there is no way to force recirc, you are at the mercy of the climate control logic.

Thanks for the links.

Slightly off topic, has anyone tried to clean out the evaporator by reversing the blower direction (change polarity) and help it along with a leaf blower to clean it from inside out?

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I have not tried that one.

Ever since I bought an inspection camera, I have been wanting to use it. I might drop the blower and shove that camera down in there and see what the evap looks like. If there are leaves and things in there, I will attach a piece of heater hose to my vacuum and shove that in there, then finish it up with some coil cleaner.

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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

About two months ago I installed a Kilma Sanden conversion kit and stuck with stock condenser and R12. When ambient outside temps were in low 80's I was seeing 34 degrees at center vent now that temp has reached 95 I am lucky to see 48 degrees, I am having same problem the evap does not get cold enough for ETR sensor to cycle compressor. I decided to purchase the kit with TXV and dryer. Everything is functioning properly Fresh/recirculated air flap, heater valve is closing, main air flap is working, electric fan turns on. Aux pump is off, sight glass is clear and pressures measure correctly, no CC belt slip. Does
anybody have any Ideas? Thanks

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84 300 Turbo / 320,000
96 E300 D / 55,000