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So I parked my 2012 E350 at the airport about a week ago. When I came back suddenly my AC is not blowing cold. I got a message that the Aux battery malfunctioned so I replaced that. Other than that there were no signs. Brought it to an independent shop and they tested pressure and refrigerant. They even evacuated it and repressurized it and it just won't blow colder than around 60-65 F. No leak and tested fine. If I drive around with it full blast it's barely comfortable. unfortunately, I am in central Florida and that's just not going to cut it. Any ideas? That particular shop wouldn't replace the compressor so I have called Mercedes and another European shop and they pretty much want identical to replace at $2200. Any thoughts on what else I might be missing or is that just it?
don't change parts for no reason...
I am sure A/C in Florida summer is a basic must have.
Try this:
Set temp to LO then adjust blower speed manually to get comfort.
Why:
When you set a comfort temp to "65", the HVAC Controller uses the heater core to blend a temperature based on its array of dozen sensors all over the place... it comes out not too comfortable!
When set "LO" HVAC controller stops circulating 200°F hot coolant near the cold A/C Evap.
A/C system is more effective and powerful without any heat being introduced
The big question:
Why exactly does the smart blended air temperature ridiculously suck so much??
(some sensors unavailable: footwell, OCP?)
If LO does not deliver frigid air then your refrigerant circuit may need evaluation: slow leak, compressor, TXV?
That is where I'm at now. LO full blast is the only way to get cool air but that is all, just cool. Cooler than outside for sure but not cold. Thanks so much.
How dirty is your cabin filter... new or plugged up?
What pressure data do you read ?How about Hi/Lo gauge-set: 180/40psi
Don't be tempted to overcharge to boost cooling.... that is counter productive. Same thing for not vacuuming lineset: ice dams.
These systems have countless ways to distinction disfunction
Test to pinpoint hot heater core issue:
courtesy of @juanmor40 hands-on investigation "RUN A/C WITH COLD ENGINE"
If perfectly cold then the refrigerant circulation is A-OK. That's half the battle!
I suggest going after heat transfers:
- heater core valve/pump
- wrap your Hi side line
Report testing ✅
Last edited by CaliBenzDriver; Aug 3, 2022 at 03:20 PM.
Thank you Juan for setting things straight with these docs. I've read all four and came away thinking this is prefacelift without the electric circulator. (It does show one but for stationary heater option).
The eye opener is the heater core is always circulated with unregulated 230°F coolant. That explains why the A/C cooling performance is weak at best. unregulated heater core kept steaming hot
My guess is they're trying to keep mildew smell down by evaporating condensate.
The issue is the heat finds it's way through all the plastics... keeps A/C poor. The heater core control valve has gone missing...
The obvious fix for tropical climates is to keep hot coolant from reaching heater core. Replace the heater thermistor sensor with a 2¢ resistor to cheat AAC thinking core is hot the way it likes it, then no fault code!
For everyone else: "LO" setting prevents blending heated + cooled air. Output is straight cold air.
The challenge now is to manage coolant flow without introducing weaknesses in that circuit. Japanese heater valve 👍
advanced aftermarket control...
KISS principle wins 😜
Last edited by CaliBenzDriver; Aug 3, 2022 at 03:18 PM.
Is it possible the little flappers/doors are not closing or sealing like they use to? Not sure of how they seal.
yes, there maybe some of that coming to play to knock down A/C best efforts. Pretty sure they use some kind of foam seal around flaps and we know what to expect with aging rubber above 200F
However it's not a primary concern. I can testify driving my brand new 2,000Mi car in 105°F California dry heat. I was so underwhelmed by the poor A/C performance, I rushed into the nearby HomeDepot to cool myself off and started to wrap my A/C heat exchanger pipe right that day.
Now I understand why cooling performance as sucked from the get go: uninterrupted hot coolant!
@Senecat, do you know the poor's man approach for testing the solenoid valve?. as far as I understand it I should isolate the problem by separating the connector at the compressor and then
1 - Measure the incoming voltage at the connector, and it should be between 4V-10V, and never 12/14V because that will imply 100% demand/load. If that is the case the failure is upstream --> AC control unit
2 - Provide adjustable voltage input to the compressor within the 4V-10V range, and check pressure gauges to see how the low pressure side approach its lowest expected value, and the high is as expected as well. If the pressure on the low side remains above 50psi->70psi despite the imposed voltage, the failure is on the compressor side. However, it may as well be the compressor mechanics and not the electronics, correct?
I think 2, separate the issue into two: compressor side vs control unit side, but before opening the system is there a way to test the valve? I read somewhere of valves with acceptable resistance, but still failing.
Yes please, clamp tight the coolant input hose to heater core. Me also want to know ........
Me mixing flap is healthy, so I am really curious how the test result will be.
I think 2, separate the issue into two: compressor side vs control unit side, but before opening the system is there a way to test the valve? I read somewhere of valves with acceptable resistance, but still failing.
Idk and I never really cared to get technical with it. The solenoid is stuck. Either pull it and clean it/bench test it or don't even bother because a new one is only $40.
Idk and I never really cared to get technical with it. The solenoid is stuck. Either pull it and clean it/bench test it or don't even bother because a new one is only $40.
Since I do not have the equipment to recover the refrigerant, I was trying to minimize $$ trial and error and frustration if that is not the cause. I am diagnosing a W211 AC (separate thread), and I need to fix other things first anyways. But I will keep this solenoid in mind.
Since I do not have the equipment to recover the refrigerant, I was trying to minimize $$ trial and error and frustration if that is not the cause. I am diagnosing a W211 AC (separate thread), and I need to fix other things first anyways. But I will keep this solenoid in mind.
tHAT'S just cya stuff for them. Of course proper diagnosis is required.
There's no chlorine in 134a. Just vent the refrigerant into the atmosphere, won't hurt a thing. Just don't let your bored, looking for "social injustice" raging libtard neighbor Karen see it.
tHAT'S just cya stuff for them. Of course proper diagnosis is required.
There's no chlorine in 134a. Just vent the refrigerant into the atmosphere, won't hurt a thing. Just don't let your bored, looking for "social injustice" raging libtard neighbor Karen see it.
Please don't do this.
How harmful is R134a to the environment? The warming potential of R134a refrigerant is 1,410, meaning that the release of one gram of R134a would have the same global warming effect as releasing 1,410 grams of carbon dioxide.
Not disagreeing, but 1400 grams is less than a human breathing for a day which can be as much as 4500 grams, also CO2 is .03% of the atmosphere, of which all human releases including cars and industry account for just under 3% of that, just want to keep things in perspective
I had this issue with my 2010 E550 when out of the blue my A/C stopped giving cold air. Barely cooled air came out of vents.
First thought was the refrigerant had leaked out so i added some and it got worse. Also the fan in front of car started screaming at full speed.
This problem started with the system never serviced before.
After things got worse with adding refrigerant the logical thought was that perhaps the system is overcharged. I let some out, about 5 psi worth on low side gauge (pressure before adding), and the system started working and is still working fine after some years of this incidence.
It is very easy to test if the system is overcharged. Just let refrigerant out in a couple psi steps and monitor air temp out the vents. You need a pressure gauge on the low side to do this.
At the point air temp goes higher you know overcharge is not the issue and you can add refrigerant charge back to level where it was.
A shop working on the ststem evacuating it and then adding refrigerant back by MB instructions does not fix anything if MB charge is too high to start with, which was the case with my car.
Hey @bmwpowere36m3 longtime no see!
We miss you around here, thank you for stopping by.
How is your new baby doing??
👏
We're doing great, thanks. How time goes by... he's almost 2 and into everything. Might be switching to the darkside... transverse, FWD, GLA. Wife's not liking the size of our W212... which isn't a bad things since I recently unloaded my W124 wagon.
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