[DeeDee]

I purchased a 2021 GLA 250 last December and after owning it for a few months the AC was making a very loud sound and not cooling correctly. I took it back to the dealership and explained what the problem was. I left it at Mercedes for a few days to be repaired. When I picked it up I was told the AC was loud because of twigs getting in the vents. I was very reluctant to believe that this was the problem. After only one day the AC began to make the same noise and it was not cooling correctly. It is back at the dealership being repaired. I would never think that a brand new auto especially a Mercedes would have such a problem. They should replace the AC. I am very disappointed and will most likely not buy another Mercedes. What are your thoughts? Did anybody else experience this problem?

 

[Huey52]

Welcome to the forum and your GLA.

Any AC system, whether it be in a home or vehicle, needs a clean condenser section. This is the system's discrete radiator and as such the fins especially need to be clean/clear of debris so that cabin heat may effectively be transferred to the exterior.
So, there is some merit to the service entry if it were truly blocked by environmental conditions (dirt, leaves, twigs, etc). When washing our GLA I make sure to stream some water thru both the AC and the engine's radiators. Same for a couple times my home's condenser during the cooling season. We have a lawn service and post-mow they use powerful blowers that kick up a lot of dust and so mine gets coated.
And of course cabin vent/duct airflow blockage and/or the cabin airflow fan itself could also be issues.
Less likely is a leak in the refrigerant line requiring repair, refill and pressure balancing. Don't buy one of those DIY refrigerant canisters. First off it's probably the wrong refrigerant type. But more important is that a certified pro will balance the high/low pressure sides which is very important to proper operation. That DIY "solution" only addresses the high pressure side and therefore can cause too much refrigerant to be applied which, much as too much oil, can actually cause more problems than it resolves.
Other sources of noise are the belt for the compressor slipping or its pulleys unbalanced, and the vanes of the radiator fan(s).

btw: Do you notice some water dripped on the garage floor/driveway after a drive in hot weather? If so that is normal condensate dripping off the AC cooling coil and actually a good thing, as if it doesn't then the coil itself is freezing up due to poor airflow across the coil, again usually caused in part by a dirty condenser radiator. Caveat: if you're in a very dry desert area you may not see condensate as it is quickly evaporating.

Now that you're on record with your dealership's service should it happen again near term they'll have to do more diagnosis and further rectify if necessary. Do let us know if you have continuing issues.

 

[Earthdog58]

I have the same issue with mine (same year and model), it’s due in to the dealer shortly and I’ll report back on their response. Interestingly, my wife has the same vehicle and it’s AC is fine.

 

[Earthdog58]

Just back from the dealer with a new fan fitted under warrant. No questions asked and it’s now working fine and quiet.

 

[Steman999]

I purchased a 2021 GLA 250 last December and after owning it for a few months the AC was making a very loud sound and not cooling correctly. I took it back to the dealership and explained what the problem was. I left it at Mercedes for a few days to be repaired. When I picked it up I was told the AC was loud because of twigs getting in the vents. I was very reluctant to believe that this was the problem. After only one day the AC began to make the same noise and it was not cooling correctly. It is back at the dealership being repaired. I would never think that a brand new auto especially a Mercedes would have such a problem. They should replace the AC. I am very disappointed and will most likely not buy another Mercedes. What are your thoughts? Did anybody else experience this problem?

hi there ive just bought a 2016 diesel with only 17,000 miles on the clock and having lots of noise for my air-con the garage has re-gassed but still very noisy don't know what to do....!

 

[Huey52]

Does it sound like the belt slipping on the pulley? Although the shop should have noted same. Actually they shouldn't have let it out of their shop if it was noisy. More insight in my post above.

Hopefully a qualified shop that balanced the high/low pressures and not just "re-gassed" more refrigerant, the latter which can actually do more harm than good.

hi there ive just bought a 2016 diesel with only 17,000 miles on the clock and having lots of noise for my air-con the garage has re-gassed but still very noisy don't know what to do....!

 

[Starck703]

I purchased a 2021 GLA 250 last December and after owning it for a few months the AC was making a very loud sound and not cooling correctly. I took it back to the dealership and explained what the problem was. I left it at Mercedes for a few days to be repaired. When I picked it up I was told the AC was loud because of twigs getting in the vents. I was very reluctant to believe that this was the problem. After only one day the AC began to make the same noise and it was not cooling correctly. It is back at the dealership being repaired. I would never think that a brand new auto especially a Mercedes would have such a problem. They should replace the AC. I am very disappointed and will most likely not buy another Mercedes. What are your thoughts? Did anybody else experience this problem?

We had the same problem with our AC - Sounded very loud on high - but cooled well. Took it into dealership and they said that Mercedes offered a one time "courtesy" repair for me - but next time I would have to pay - and they told me not to park under trees where leaves fall.... Service rep said it happens all the time to many Mercedes. 3 months later its happening again and has been parked mostly in the garage. I don't think it's leaves.... I also read somewhere that MB doesn't put a filter before the fan and it sucks in trash. Seems like a design flaw to me.

 

[Huey52]

I've never seen a filter integral to a radiator fan in any vehicle I've ever owned. There is sometimes a stone screen however, but that's more to stop churned up impact from vehicles in front of you that might puncture the radiator (oil cooler as well as A/C & engine coolant). A filter media would needlessly reduce airflow to the radiator(s).

Again, it is important to periodically flush the radiator fins and to also clean the fan blades. Annually I clean out leaves and also try to avoid, but traveling any backroad in Fall it's impossible to completely do so. On some vehicles I have to drop the plastic belly pan to reach them and even then tedious.

We had the same problem with our AC - Sounded very loud on high - but cooled well. Took it into dealership and they said that Mercedes offered a one time "courtesy" repair for me - but next time I would have to pay - and they told me not to park under trees where leaves fall.... Service rep said it happens all the time to many Mercedes. 3 months later its happening again and has been parked mostly in the garage. I don't think it's leaves.... I also read somewhere that MB doesn't put a filter before the fan and it sucks in trash. Seems like a design flaw to me.