I noticed the interior temperature was not very cool, so I decreased the thermostat until I eventually had it on MAX Cool. I noticed the vent air was not very cold and had low airflow. When I got home, I put a digital meat thermometer in the vent, and it got down to 51.6F on MAX Cool. BTW, outside temp is 86F with 73% humidity.

Do I have an issue? What might the issue be?

Thanks.

 

Please scan for codes, and monitor live data: refrigerant pressure, electric solenoid valve duty cycle, evap temperature etc.

 

Unfortunately, my code reader will not do that. When I tried, I did notice the AC felt cooler, so I checked the vent temp again and saw that it was better - 44F

 

Perhaps you should repeat your A/C test with engine cold.

The W212 has NO heater core valve.

The 210°F coolant is always fully circulated not far from A/C evap coil.

In hot summer this setup limits cooling effectiveness.

 

I say you have issue but who knows what issue is without having car in my driveway.

Chek filter
Check evap for clogging with mold yucky stuff
Check for Codes (Dealer or fancy code reader)
check temp blend door
check refrigerant pressures (hi & lo)
Check electric engine fans.
Check condenser for blockage from dead bugs etc.

How is it at interstate speeds?

 

You had nearly 50F output, on a day when the outside temperature was 85F give or take? That’s a 30F drop. I don’t know if you have a recirc setting, but if you did, and you used it, with all the windows and any other vents closed, that should cool you down rather quickly. In residential air conditioning, a 20F drop is considered adequate. Once you get your interior temperature down to a comfortable level, you could then deselect recirc. Of course, I am not disagreeing with any of the other advice already given.

 

MB typical evap temperature setting is +2C or 35.6F
The AC computer will show you that, using scanner.

If all OK with engine and HVAC system, and then your engine is M276 which has no heater core electric valve to shut offf coolant to heater core, this is what will happen :

AC air is RECYCLE MODE and not fresh air.

01. Start engine COLD, assume ambient is 30C or 86F. Car is stationary in this scenario and not sunlight heated, garage kept or full under the shade.
In 25 seconds after engine oil yada yada flowing good to all around your engine, you then turn on your HVAC at 21C or 70F setting or lower.
In approx 4 or more minutes, your HVAC should be doing its best already, which is close to 2C or 35.6F as per EVAP temperature sensor.
At your mid vent, left or right side does not matter, setting of vent flaps is to passenger only , blower speed 3 or 4 bar, you should get no warmer than 6 to 7C at the vent or 43.8 to 44.6F .

02. When and if engine already full warmed up with thermostat already opening usually 20 minutes after engine start ,
heater core heat will contaminate your EVAP cooling power by up to 3C or 6F and you may see 9C or 48.2F
No matter what you do, heater core is a dumb-azz always contaminating heat to evap , due to its close proximity to the EVAP, albeit there is a flap.
Ambient of 30C to 2C is 28C delta.
Coolant temp 30C to 95C is 65C delta and engine is a massive heat generator. HVAC suffer.

This is my car at 32C ambient temp after I replaced my cabin filter to the Ferocius Plus version with pollen trap, from MANN.
I let it idle for 20+ minutes at least. I have removed ( by-pass) the coolant circulation to my heater core. I am in the tropics, I do not need heater. I need HVAC 24/7 even at night when I use the car.

.





IF LOWEST TEMP MODE, at the vent 3 inches into the vent = 5.0C or 41F
I even use floor vent mode + passenger/face mode, thus in theory less cooling power to my middle vent ( passenger/face).





If I set to 21C or 69.8F, I get 5.2C ( 41.36F) at the middle vent


.





That 5C or 41F sensor TMP-1A label 1 , left gauge , top left.... that is the "exhausted" refrigerant fat pipe skin temperature at the EVAP TXV, near firewall. Suction pipe we call it or the blue color
coupler pipe when one uses those red and blue R134A coupler.



If departing "coldness" is still 5C /41F, can you imagine how good the EVAP is at removing heat ( making cold ) actually is at its surface area or assy, when and if the heater core is not contaminating it.

Label 2 is the condenser output pipe skin temperature.
Label 3 is the HVAC compressor pipe output skin temperature.
I monitor this to prevent HVAC compressor overheating death.
R134A critical temperature is 101.1C or 214F , above this it can no longer be liqufied and my compressor and its oil will also suffer.
HVAC only works ( cold ) if the R134A from liquid state can be converted to gas state, as in EVAP system.
That is why dirty condenser is very harmful, and so is dirty EVAP.

-----------------

This is how cold the W212 HVAC is when properly maintained and if heater core is eliminated.
I win/gain approx 3C cooler vent temperture for elimination of heater core hot coolant circulation.

W204 and W212 C200-C250 or E200-E250 with gasoline M271.8 engine, its HVAC is freaking cold, as there is a valve to stop the heater core from circulating hot coolant.
We M276.xx are loosers .

BEWARE :
M276.xx CAN NOT have its heater core coolant hose from engine to be blocked, you can by pass the heater core but that hot coolant hose from engine
Bank 2 rear azz has to go back to the mechanical coolant pump suction port at engine.


Given at the age of your car, go find a good HVAC shop with a good RRR machine that has refrigerant detector and is willing to vacuum your HVAC for at least 2 hours ( pay more ).
8 grams per year is the "natural" R134A leak at the compressor dynamic seal, when car is used well and can be more leaky if car seldom get driven.

Good luck troubleshooting ur HVAC.

 

Yesterday nite I washed my car.
The one thing I hate the most is cleaning the wheels.......why ? Because the water will wet my brake rotor and brake pad and if I do not drive around after washing, it will rust my disc rotor and jammed up my brake.
When I was almost done shampooing the car, rain started...DAMN !!! This means I can not drive out the car to dry the brake system.

So I was like a fool, reversing and moving forward in my own 15 meters long garage to dry the brake system and use compressed air.
So I thought it was dry enough. This late afternoon I wanted to jack it up and I pushed it a bit forward ( I do not like engine start for 30cm movement ).
QuickJack will move car forward or backward about 20cm when lifting depending on how you set it up, it is the nature of the design using links and not pure push up like workshop 2 stand 4 points lift.
The freaking brake was locked due to rust, yep , merely 18 hours wait only.

So I got to start the car and AGAIN, play the fool in the garage forward + reverse playing with the brake, me too lazy to drive out of the house if at crazy peak hour 5PM ish.
Thus I can show you guys what a virgin HVAC performance of W212 can do, when and if our engine is started from COLD of 30C temperature.
Every damn thing on the car is at 30C. So it is a very very nice temperature for HVAC to work.

When at engine kill after a drive and heat soaked and then you star the engine and AC 30 minutes later, no matter how good is our fake firewall heat shield hiding the wiper assy and
thus the TXV and EVAP firewall section, engine bay heat will heat all up.
It will heat up our compresssor, our hoses and our mini internal heat exchanger at the pipe and the condenser....every dam thing and that alone is parasitic load.

Here is the log.

TMP1A is EVAP fat pipe ( outlet /suction ) skin temperature.
TMP 1B is condenser output at its metal section pipe skin temperature
Compressor outlet Temp is , the L steel section pipe at compresssor outlet skin temperature. L pipe is steel and then rubber hose.


.

Below, T Open means engine coolant thermostat open, thus we can see the engine bay temperture ( under hood ) , suddenly rise up a lot.


.


Above, initial temperature of EVAP fat outlet pipe being -2C at start of HVAC operation is common.
See how the EVAP is being controlled by the HVAC computer to try to maintain its 2C set temperature.

.

Below is how I warm up my engine when I dont use it on the road. Usually 25 minutes, but today me lazy.
The middle section data point 875 to ,1863 is me moving forward and reverse in my garage clearing rust on the brake like a fool.



Hope this is useful info for you guys.

.

 

Too bad you are 1/2 a world away from the USA....Ever consider a flying mechanic job? LOL just kidding.....

 

Yeah. The tropics have a lot to be said for them. I know the South Pacific well, as I have been all over in there. I enjoyed my time there, but am happy that I am not still there.
The nice thing about the US, is, you can live in the climate that you want to, 100% of the year. It might take having to move from North to South, to stay in the climate band you enjoy, and you can even have the convenience of having a house, or condo, or timeshare, waiting for your arrival coincident with your choice climate.
An added plus, is you get to see the change of 4 seasons, instead of being stuck with 1.
So let’s start a call for Prihadi to bring all his business and expertise here!

 

I love living in Indonesia, my little $$ works wonders.
Everything here is Voice Control for me.
If I want coffe, I do a mild shout to my female servant, and in 3 muinutes coffe is on my table.
When I am about to reach home, I call my male servant , "open gate and garage door"........... abracadabra = Both gate and door opened and closed by itself too.
AI powered by rice and chicken

Going to the mall, use my wife's car and her driver. No need self driving Tesla.
My wife equivalent of "Tesla" can park itself and carry the shopping bags all the way to the kitchen when I reached home, and wash the car too

-----

For my own E400 I hand washed it myself, it is excercise for me and pleasure too, as such I know every smallest ding on the car and I get to inspect visually a lot of the car stuff.
I blow dry my sunroof deflector net type cloth.
I blow air into 4 corners of the pano roof water exit "vent", there is no hose for panoroof water exit, it is a differen strategy than regular sunroof.
After that I place my dehumifier inside, at the rear floor and run it for 4 hours, because cleaning the car with open doors make the interior at 85% humidity and that is not good.
I place a humidity sensor on the car, that small white thingy and I dehumify again when humidity inside the car reached 70%. Usually 4 days later.

Car is always under cover, due to the dust is so insane in my city.

This last 10 days I been running around to my friend's yacht , helping them on electrical issue.
Thus my car get dirty from the rain for like a week already. So me gotta wash it.
I wiped every part of the interior with 50% diluted Simple Green yesterday.
This past 90 days the humidity been severe and all the fake chrome plastic at the interior sems to be harboring "mositure".

Also lots of micro dust and I smoke in the car you see, so small white ash will fly around.

The Mann Fericous Plus Cabin Filter is really nice, complemented by the ion generator on my dehumifier and Simple Green total wipe, it make the car smell-less.
Not even leather smell....not bad at all.

 

OP here. The mechanic found that the refrigerant was low due to a slow leak. He added 19 oz of refrigerant and also a dye and told me to bring it back when it starts blowing warm air again so he can see where it is leaking from. He said it may take a few months to a year before that happens.

 

The leak is likely caused by the Schrader valves. If curious, and you have the UV light, you can now shine it at the valves after removing their caps.

 

It is common to leak there? If so how do you replace it or do you have to replace all the hoses?

 

Need to evacuate the system, replace the valves, vacuum the system, and recharge. I did it on the W166 (link below)

Of course, MB wants to sell you the line with the Schrader valve (standard racket).

https://mbworld.org/forums/m-class-w...ml#post8702673

 

Thanks, a lot of work but thanks for the tutorial.

 

The plastic cap of the schrader valve cover ( service port ) has o-ring. It does help seal when and if schader valve does leak.
When we open the plastic cap and you sense positive pressure, that meant the schrader valve leaked.

This is one severe case from an old W221, its very obvious.

..

 

Ah more common than I initially expected.

 

I just remembered we were talking about those valves on a different thread. Might want to also try this kit? https://mbworld.org/forums/mercedes-...ml#post9157107

 

My compressor cut out when temp reach 1C and cut in when 4-5C. Normal or abnormal? E300.2009 thanks

 

4.10 seem low, no?

 

Looks like that particular kit doesn't work, see the other thread.

 

I don't know, because it looks work like conventional compressor, cut in and cut out. Do you think it suppose to work steady, since the compressor has solenoid?

 

The solenoid is what makes it variable. It allows the ECU to control the level of cooling at a fixed RPM even if the magnet is fully engaged.

I would need to record mine to compare to yours. To me, 1 C is border line freezing the evaporator, so it must be cooling well. Recall there a few sensors outside, and inside to keep the AC at the set temperature.

 

I see, it is in Celsius. I thought we were looking at Fahrenheit numbers, my bad.