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Hi guys, I have a 2015 C220d bluetec, and the aircon is driving me nuts. I have had it serviced and fluids and all other stuff are topped. There is no errors nor a leak. But the cooling of the aircon is so damn weak. It can barely cool the car on a sunny day where the outside is 19 degrees.
Is this car just weak in cooling? this is my first mercedes and I remember both my old volvos chilling the car like a fridge! Any guides will be much appreciated.
Who serviced it, what did they do? I havent worked on mine but reading thru the manuals it seems pretty complicated, the refrigerant is weighed and doesnt go by pressure.
May be a dirty evaporator. They have a procedure for cleaning it which seems fairly easy to do. Basically take apart the cabin air filter to remove the filter part, drill a hole in the base to fit the cleaner nozzle, then spray it in with it running.
I find the AC in the W204 to be a beast of a system. At 258k miles it still beats out everything in our garage. I do service it every 3-5 years to keep the gas at proper pressure. Emphasis on "proper". Cooling performance is decreased when the system is over or under filled. I don't use pressures to gauge an accurate fill but instead via weight with a proper evac and recharge for a good (known) baseline. From there you can just top it off in 50g increments every 3-5 years using a kitchen scale.
Quick check would be if you're having to crank the thermostat down lower than you used to then it's probably under. Fan screaming like a banshee at moderate ambient temps, then it's probably over. Caveat, this is on a US model with the following option:
You can just catch a glimpse of the temps this car can operate in. Chillin' in 127 deg temps with the tunes to go with it:
Hi guys, I have a 2015 C220d bluetec, and the aircon is driving me nuts. I have had it serviced and fluids and all other stuff are topped. There is no errors nor a leak. But the cooling of the aircon is so damn weak. It can barely cool the car on a sunny day where the outside is 19 degrees.
Is this car just weak in cooling? this is my first mercedes and I remember both my old volvos chilling the car like a fridge! Any guides will be much appreciated.
Originally Posted by TimC300
Who serviced it, what did they do? I havent worked on mine but reading thru the manuals it seems pretty complicated, the refrigerant is weighed and doesnt go by pressure.
May be a dirty evaporator. They have a procedure for cleaning it which seems fairly easy to do. Basically take apart the cabin air filter to remove the filter part, drill a hole in the base to fit the cleaner nozzle, then spray it in with it running.
I find the AC in the W204 to be a beast of a system. At 258k miles it still beats out everything in our garage. I do service it every 3-5 years to keep the gas at proper pressure. Emphasis on "proper". Cooling performance is decreased when the system is over or under filled. I don't use pressures to gauge an accurate fill but instead via weight with a proper evac and recharge for a good (known) baseline. From there you can just top it off in 50g increments every 3-5 years using a kitchen scale.
Quick check would be if you're having to crank the thermostat down lower than you used to then it's probably under. Fan screaming like a banshee at moderate ambient temps, then it's probably over. Caveat, this is on a US model with the following option:
I googled "2015 C220d bluetec" and all that came up were 205's. So I'm guessing it's indeed the next generation to ours. That said, AC maintenance procedures, tips and tricks most likely carry over.
I googled "2015 C220d bluetec" and all that came up were 205's. So I'm guessing it's indeed the next generation to ours. That said, AC maintenance procedures, tips and tricks most likely carry over.
It should, I think the tips applies to any car really.
All great tips thank you both forum members.
Is OP's vehicle a W204 or W205?
good question, its a EU one. Its W205.
The service was done in an authorized mercedes shop, not a dealership itself. I am thinking is there any known issues where the service centers cannot really find anything "wrong" per se but its not fully functioning? There is no way a car of this scale cannot cool the cabin in Stockholm in spring!
The service was done in an authorized mercedes shop, not a dealership itself. I am thinking is there any known issues where the service centers cannot really find anything "wrong" per se but its not fully functioning? There is no way a car of this scale cannot cool the cabin in Stockholm in spring!
What temperatures are it usually? How is the climate control set as, auto? auto fan speed, auto airflow direction? All the vents are fully opened?
What temperatures are it usually? How is the climate control set as, auto? auto fan speed, auto airflow direction? All the vents are fully opened?
I have tried 2 ways
1. All vents are open, everything is on auto and air intake is both tested to be from outside AND then after that with recirculation
when i go to LO temperature, the car (engine compartment, but my RPM is fine, there is nothing weird going on when i open the bonnet) sounds like its opening a portal to mars and keeps giving me average temp at full blow speed and its pretty warm. like you wont feel it being "cold wind"
when i go 16-19 fan goes high, temp is the same garbage
above 19 fans go low and temp is same garbage
2. all vents are open, everything is on manual, tried both with open air from outside AND recirculation
well, fan speed dont matter because i control it
temps are same garbage, imagine ambient but warmer. on low temps the car makes the same sound
general note> the cooling does get a bit better after maybe 10 minutes of driving. but i cannot say it gets good. on a 19 degree sunny day I was sweating in linen shirts in the car and the actual air outside was cooler to the touch when i got out of the car.
the car makes a lot of "working" sounds when i put the temp on Lo or anything like 16-17. its not bad noises its like what would happen if you revved the car. of course the RPM is normal and unaffected
what i mean by cold air is i have to hold my hand to the valve, at decent fan speed like 3 and up to feel a "cool" sensation from the wind. otherwise its literally warm, not warming the car warm, but warm air. imagine sitting at home on a summer day in shade.
sorry for the lectures but im getting really frustrated by this seemingly ridiculous issue.
Get a proper baseline. Go to a dedicated auto AC shop and have it evacuated and filled by weight. Machine sucks out all the gas, weighs it, then fills it according to the amount specified on the sticker under the hood. Then you pay the variance, aka the amount they added. Unless your system is really down, which it could be after 10 years, it will cost between $90-$150 USD. Well worth it from a diagnosis perspective.
My guess from the information presented so far is that the gas is low. Refrigerant loss in mobile AC systems is normal to a certain extent. If you want to read the study the Germans did on it, see attached.
tl;dr page 47, 6.3% per year is considered normal.
I have tried 2 ways
1. All vents are open, everything is on auto and air intake is both tested to be from outside AND then after that with recirculation
when i go to LO temperature, the car (engine compartment, but my RPM is fine, there is nothing weird going on when i open the bonnet) sounds like its opening a portal to mars and keeps giving me average temp at full blow speed and its pretty warm. like you wont feel it being "cold wind"
when i go 16-19 fan goes high, temp is the same garbage
above 19 fans go low and temp is same garbage
2. all vents are open, everything is on manual, tried both with open air from outside AND recirculation
well, fan speed dont matter because i control it
temps are same garbage, imagine ambient but warmer. on low temps the car makes the same sound
general note> the cooling does get a bit better after maybe 10 minutes of driving. but i cannot say it gets good. on a 19 degree sunny day I was sweating in linen shirts in the car and the actual air outside was cooler to the touch when i got out of the car.
the car makes a lot of "working" sounds when i put the temp on Lo or anything like 16-17. its not bad noises its like what would happen if you revved the car. of course the RPM is normal and unaffected
what i mean by cold air is i have to hold my hand to the valve, at decent fan speed like 3 and up to feel a "cool" sensation from the wind. otherwise its literally warm, not warming the car warm, but warm air. imagine sitting at home on a summer day in shade.
sorry for the lectures but im getting really frustrated by this seemingly ridiculous issue.
Don't worry about that at all, fully understand.
Still sounds like it is low on refrigerant, not sure why your authorized MB shop couldn't figure it out though.
Get a proper baseline. Go to a dedicated auto AC shop and have it evacuated and filled by weight. Machine sucks out all the gas, weighs it, then fills it according to the amount specified on the sticker under the hood. Then you pay the variance, aka the amount they added. Unless your system is really down, which it could be after 10 years, it will cost between $90-$150 USD. Well worth it from a diagnosis perspective.
My guess from the information presented so far is that the gas is low. Refrigerant loss in mobile AC systems is normal to a certain extent. If you want to read the study the Germans did on it, see attached.
tl;dr page 47, 6.3% per year is considered normal.
Get a proper baseline. Go to a dedicated auto AC shop and have it evacuated and filled by weight. Machine sucks out all the gas, weighs it, then fills it according to the amount specified on the sticker under the hood. Then you pay the variance, aka the amount they added. Unless your system is really down, which it could be after 10 years, it will cost between $90-$150 USD. Well worth it from a diagnosis perspective.
My guess from the information presented so far is that the gas is low. Refrigerant loss in mobile AC systems is normal to a certain extent. If you want to read the study the Germans did on it, see attached.
tl;dr page 47, 6.3% per year is considered normal.
Originally Posted by W205C43PFL
Don't worry about that at all, fully understand.
Still sounds like it is low on refrigerant, not sure why your authorized MB shop couldn't figure it out though.
Did you try another authorized MB shop?
they did refill a bunch of things, but result is pretty much the same cooling sadly. I auto translated it from swedish what they found in their work.
@CaliBenzDriver Looks like we are stuck, do you mind helping out please.
let me read... I see compressor oil then... what's next suspect??
let's now remove the cabin filter for good measure.
+++ Ok after further reading:
I understand original compressor survived various shop visits.
Lucky you!
Cooling is based on the amount of gas cyling through the TXV. Meaning more charge hurts the low side pressure. Pls don't over charge looking for results unless system is low.
We know modern A/C should be charged by doctors using a scale... BUT:
you can tell if it's low or not by reading resting cold pressure - It's not super precise but right now who exactly cares. (pressure varies with temp).
Use scanner to read your AAC data:
what's the RESTING COLD pressure
what the valve duty cycle at idle
what are the various reported temps
I am not pinning it on any control parts just yet, lets not jump to conclusions or big ticket repairs.
Data will tell us what the reality here.
Last edited by CaliBenzDriver; May 17, 2025 at 11:34 PM.
let me read... I see compressor oil then... what's next suspect??
let's now remove the cabin filter for good measure.
+++ Ok after further reading:
I understand original compressor survived various shop visits.
Lucky you!
Cooling is based on the amount of gas cyling through the TXV. Meaning more charge hurts the low side pressure. Pls don't over charge looking for results unless system is low.
We know modern A/C should be charged by doctors using a scale... BUT:
you can tell if it's low or not by reading resting cold pressure - It's not super precise but right now who exactly cares. (pressure varies with temp).
Use scanner to read your AAC data:
what's the RESTING COLD pressure
what the valve duty cycle at idle
what are the various reported temps
I am not pinning it on any control parts just yet, lets not jump to conclusions or big ticket repairs.
Data will tell us what the reality here.
Hopefully that helps OP, hopefully OP can get back to us.
Not too many things are known to go wrong with A/C... not too many are cheap to fix.
It may not be silly to replace cheap pressure switch now preventively.
No guessing without data
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