Long story short. I have visited the dealership for ac problem and been advised of replacing evaporator and compressor (it says "should be replaced").........



Once the evaporator removed (my DIY), both water test (by 250 psi pressure) and vacuum test were done. BOTH NEGATIVE for leak..!!??

Forgot to take pics for water test. But sure no air bubble out.....

Vacuum test below......




I don't know why the dealership said the evaporator should be replaced, but I am sure I will never trust it again and will at least have a second opinion when doing such big job...........

Now have to spend time to install the new one....

 

Are you tring to use vacuum pump as leak testing device for evaporator ?
The two photos , 4:09 PM is when you held pressure close to -950millibar vacuum with vacuum pump off and shut off valve closed at vacuum pump and 6:09PM as maintained vacuum pressure for 2 hours ?

 

For sure: dealers, especially MB dealers/SA's are crooks. Hope you can find a good indy shop

 

These two parts pointed by your MB Dealership are the two most unlikely to be defective in A/C systems... this is seriously misleading. Best training shines

The advanced Mercedes A/C does not need to leak to cool poorly - The compressor governor valve gets stuck and the pressure sensor goes bad likely due to marginal water protection.

When in doubt.... use a scanner to read live "AAC Module" data: pressure, temperatures, valve PWM duty cycle,...

How did you manage to replace the evaporator unit... did you lift up the dashboard assembly??

 

Yes, 4.09 pump off and valve closed. Then wait 2 hours indoor until 6.15.....

 

Vacuum test for the new evaporator with new txv. Showed little bit vacuum decay but I think it is acceptable.

When pump off, valve closed.... 11.00pm last night


Indoor, 9 hours later..... 0813 hrs this morning

 

Yes, they are..... thank you!

 

I Would ask dealership why they think the evap and compressor need replacing?

I mean if they think compressor blew up internally and sent metal particles downstream then yes the evaporator and condenser should be replaced as they are about impossible to flush out all the debris.
Now this only applies if compressor catastrophically failed and is internally destroyed. I would also replace dryer/accumulator and whatever MB calls the expansion valve (could be called orifice)

That would be my guess what they wrote what they did.

Have you checked your compressor?
And yes since they are variable and a have valve to control displacement it is a PIA to check as you have to confirm valve works first.

I can say these new variable compressors make for better cabin comfort and tad better MPG they are Pain to troubleshoot.

 

yes, lift up evevything..... the dashboard, the crossmemebr and then the HVAC unit.... Fun time in weekend.....

 

He stated it wasn't cooling well ("insufficient cooling"), not that it didn't cool at all. Catastrophic failure would mean NO cooling at all. Of course, no cooling would be insufficient, as well.

 

Curious, but do you run your A/C all year long? Even in cold weather?

What diagnostics were performed by the dealer?

 

Hat's off to you for undergoing this procedure...

Since you're going there... then you may want to fix all your flap actuators while they are "easy to work on".

These small network modules are grease less + solderless to see extreme currents.

All of them identical but each has a specific location (mark them!).

Let me try to find couple internal pics... here:

It's literally gearbox controlled by a dual-coil motor. Note there is no positioning sensor of what exact position the gears are in.


Flap actuator module: gears + control motor


8-pins solderless interface circuit

It's simple to make these trouble-free with a dab of grease and good solder joints.

 

after visiting the dealer, i went to an ac shop for freon recharge by machine. The shop told me that only 300 more grams was recovered, which means my system is leaking.....
The ac system run "good" for only 9 months, I then checked it with pressure gauges (both sides low) and add freon by my own using pressure reading.....
After freon filling, the pressure will drop again in less than half a year, so I finally decided to have the evaporator and compressor replaced by my own.....
As to what kind of tests done by the dealer, I don't have any idea at all.....

 

I pray to all available Gods of the Universe ( and Uncle Murphy )........... please please please, do not let my EVAP leak, at least not until its 25th years old Bday or 30th Bday.
I fear of the total dashboard removal, not the $$ for the evap.
Cricket sound usually appears after old dashboard get removed and re-installed.

 

Best you do full system test pressure to 200PSI using nitrogen, where all the o-rings must first be renewed.

O-rings in use on our typical HVAC system

2 pcs at the TXV to EVAP.
2 pcs at hose end liquid (small pipe + hose ) and vapor ( big pipe+hose ), interfacing TXV.
If your HVAC has IHX ( Internal Heat Exchanger )
1 pc for condenser output to IHX, IHX side
1 pc for Compressor input/suction hose to IHX, IHX side.
2 pcs at the compressor input and output, compressor side.
1 pc for compressor to condenser INPUT hose, condenser side
1 pc for condenser OUTPUT hose , at condenser side

1 pc for refrigerant pressure sensor. But it is not sold stand alone, it comes with new refrigerant pressure sensor.

2 of schrader valve, renew both.
2 of new plastic cap with o-rings for both liquid/HP and vapor/LP service port where the schrader valve resides.

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

Compressor oil ( Denso ND-8 ) to add when replacing compressor. Do the oil balance for compressor and only add what is in the old compressor.
WIS gives information too :




Surely you must replace your filter drier, add oil:


.

.


Attached source of above,complete info in PDF.

Good luck..........

 

Listen to what about blender door control...
(our unit is the generation after without the wipers on carbon track)

 

Thanks Cali

 

Many thanks S-Pri.

My system do not have IHX, simply two lines runs along....

All old and new o rings:




The MB condenser has included a new pressure sensor and dryer. But too bad that seems it is not pre-filled with nitrogen to ensure moisture free..




Two shorter lines (to and from compressor) will be flashed with AC cleaner....



Will try to remove the longer lines (to and from TXV) and flash them....but have to see how to do (no video or worksheet found so far)..... seems need to lift up many stuff......

Of course to buy the two new valves...

Any need to replace the caps?

 

Have a replacement compressor. The package does not indicate how much compressor oil inside it.




Need to check Denso website in other country to make sure it is filled with 120ml of oil. Exact amount of what my system need ......

 

Okey, if you flushed all the hoses clean of old oil residue and new compressor + new evap + new condenser, you can then use 120ml of ND-8 compressor oil like how when the system is virgin 100% new.
The hoses + pipe from TXV if Left hand drive car I am not familiar, but on my right hand drive car and IHX, it runs from battery bay to behind fake fire wall, under wiper system.
Wiper system must be totally removed.

In your LHD car, the AC hose+pipe routing will also be the same , which is on the LEFT side of the car towards the EVAP. But but you have brake booster on your LEFT side.

This muffler like round thingy is used when system has no IHX it seems.
This is to make sure compressor does not suck liquid refrigerant , but gas form only. No IHX means superheat is less.


.

Your condenser, does it come with pre-installed filter drier ?
If it does come with filter drier and when condenser sold ( I hope not ) without being filled with positve pressure nitrogen, the filter drier will expired in no time.
Do you have new filter drier in hand ? You need new one when HVAC system open up like now.
MB filter drier comes in an aluminum tube, which is how they should be stored . Best if they vacuum pack in ALU foil too. I dont know if they do, I dare not open mine yet, till I will use mine.





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Since you are doing this on your own time, do a proper 24 hours vacuum and wait for car to warm up to ambient temperature in 6-10 hours and vacuum again 12 hours.
Vacuuming is good when in warm weather.

Does your compressor have the magnetic clutch ?
If it does, even better, you can warm up your engine to warm up HVAC component without needing to run/spin the AC compressor.

Share with us your progress....... thanks

 

While your A/C circuit is open, replace :
-- the refrigerant pressure sensor off the condenser
-- schrader valve cores high/low side.

--- Silicone seal the read end of connectors to keep water out (compressor + sensor)

The AAC controller itself is solderless module. Keep that for later as need arise.

Beware of compressor clutch coil + PWM valve having a Diode or not....
See that your replacement Denso test the same electrically as your original compressor. They should match.

 

Confusing...... how can I confirm whether the new MB condenser has the dryer? Open up and see? Or any spec i can double check ?
Thanks

 

MB offical dealer, does show photo of the EVAP with pressure sensor, but no data on filter drier.
https://www.mbpartsexpress.com/oem-p...ser-2045000654

As far as I know, filter drier is usually NOT included, as it is a last minute MUST INSTALL when HVAC system get opened up.

Also the filter drier is very expensive, usual MB throat slayer price. I paid locally more than EVAP price I linked above with its discount.

UNAVAILABLE - Filter drier
https://www.mbpartsexpress.com/oem-p...r-204835014764

Let's find in Europe
Supposedly genuine : https://www.ebay.co.uk/itm/386287346780

DUBAI :
https://partsouq.com/en/search/all?q...-cy9uedtOlyf-B

Average is US$138 for this SHOULD ACTUALLY BE LOW cost filter drier.
I paid much more from MB Indonesia. Like US$200+ DUGHH !!! but it is what it is.
Even my 3 hoses I bought for HVAC, it is 300% compared to USA price at MBPartsExpress.

Supposedly the condenser is DENSO 17305
https://www.denso-am.eu/catalog/part/DCN17035

Maybe call Denso or MB dealer and ask ?

 

Both Denso and MB do not reply..... but FCP Euro confirmed that the condenser A2045000654 does include the drier pre-installed.....
Also, a local authorized dealer of MB parts told that my condenser A2045000654 comes with 3 items: filter dryer, left and right plastic frame and pressure sensor as well. However, another parts numbered A2045000254 is solely a condenser without such three items....
For sharing.....

 

Oh, nice info thanks.
Plastic frame. I think my car being facelift the plastic frame is big and shared with aftercooler + tranny oil cooler too...and the condenser,I think so.
I have not done any teardown except for M4/7 radiator fan, which its clip rest on radiator plastic frame.