HELP! Air conditioning question!

2015 S550 with 56,400 miles. Car has been in great shape, and A/C worked last year. I bought it from my previous employer who owns a body shop (I am now a chiropractor and haven't worked there in about 5 years).

Today was the first hot day of the year, and I wanted to turn the A/C on. I turn it on, and I always turn the temperature on "Lo" on both sides, and sync the driver and passenger side. I have semi-cold air coming out of all the driver side vents (not really cold like last year), and I have slightly warmer air coming out of all the passenger vents. Definitely not hot air, but not as cold as the driver side (by a little, not much). Outside temperature today was about 72 degrees.

Also, I had no heat about 1 month ago. The heater was blowing cold air, so I had the heater control valve replaced about a month ago and the heat is fixed. I remember turning on the A/C at that time and did not have a problem. However, the temperatures were much colder so maybe I didn't notice a difference. Could replacing the heater control valve cause this?

Does anyone know what is wrong? I'm going to my old job at the body shop tomorrow morning, and my old boss said he will charge it as to maybe it is low on freon. Maybe it's low on Freon? Does that happen?

No coolant leaks, but now I have a weird sweet smell out of the vents when the AC is on. No lights on the dash. Could it be the pressure is just low as the car is 7-8 years old now?

I also attached a video on youtube back before I got my heater control valve fixed that made a weird sound with the air condition when I turned it on. Is this normal? It doesn't do it nearly as long now, but it's about 10 seconds and never goes completely away.

I hear the hissing from the AC when it is turned on. Which means leak correct?


Any help is greatly appreciated!

 

Isn't the system designed to leave it set on Auto, with the Temperature set to what you want, year round and let the system adjust heating and cooling as needed? Isn't turning it off and then on to Lo when the car gets hot just using it like an old manual system?

 

Hi! Probably? I'm not too familiar with Mercedes Benz systems. Should I always just hit the auto button?

Thank you for your reply.

 

I would put my money on that it is not the Charge. Sounds like your Airflow (Mixing Door(s) behind the dash are not working properly,

 

well, now I have a sweet smell with the AC on. Probably a leak correct?

 

If the system has not really been working a lot, I leave mine on auto all year round regardless, then the gas could be getting low and need a recharge, also the smell may be a " bacteria smell" that can also happen.
Car accessory shops in the UK sell an aerosol that you discharge and place in the footwell of the car and then you set the system to recirculation, this causes the stuff from the aerosol to be drawn through the system and back into the car and it eliminates the bacteria and therefore the smell

 

Not to be alarming, but I usually equate a sweet smell to engine coolant. You did mention prior issues with heating.

 

yes, you are right! But the heat was fixed after the heater control valve was changed.

I also read that the smell of leaking Freon smells sweet as well?

 

So, update everyone!

I dropped off the car at my Mercedes Dealer yesterday (Saturday), and they will start diagnosing tomorrow or the following day. My service advisor always tries to get me in ASAP.

What I've noticed yesterday before I dropped it off is that I was starting to get a sweet smell coming from all front vents when the A/C was on. And also, a hissing sound from the dash when the A/C was turned on and never really went away. In years past, it would hiss for about 5-10 seconds then stop. Upon reading I've found that this was a sign of a refrigerant leak.

I don't think I have a clog or anything like that so it shouldn't be too much of a job. Maybe the blend door actuator or the A/C compressor. Anyone have any ideas? I've done research and it seems that if you get cool to cold air on one side, and outside temp air on the opposite side that it is the blend door. I also have no low coolant lights on the dash so I don't think the sweet smell is coolant.

 

Not sure about the W222 but on other MB models low refrigerant may lead to cool air on one side only. The evaporator starts to freeze from the other side. Should affect air flow then too.

 

Thank you so much! I have no air flow problems as far as I can see. I'm hoping it's not anything big like the condenser or a clogged system, which I really don't think is. Do you think the low refrigerant could be just a hose or something? The car only has 56,600 miles.

 

Update. Got a call from Mercedes-Benz this evening, telling me that the car is in the technicians bay, and they ran the scanner, and had multiple faults. They said it is the blend door actuators, as well as possibly the climate control head. Does anyone know what that means? They told me that they will call me back by tomorrow evening with the total price and how long it would take to fix. They said they want to make sure that they spend time finding the right problem, as opposed to just fixing some thing. But there is no leak!

 

Multiple actuators are located in A/C housing, control head = operating unit in dash.

 

Rats so they would have to remove the dash to fix the control head???

 

And a bit more to replace actuators.

 

Ugh. So lots of labor hours?? Will everything be put back together ok or will it cause future problems?

 

Your question is best directed here: http://www.ask8ball.net/ if it's any consolation UCP (control head) controls actuators it may the only part replaced, simply requires removal of trim panel.

 

well! You are right. They called me and said entire job is about 761 dollars plus tax and diagnostic fee. They do not need to take the entire dashboard out. And the climate control head just needs a software update! Not too bad!

they said the actuators were literally stuck on both sides. So happy that is isn’t a more bigger job. However, have to wait for parts to come in. Should be done end of the this week hopefully or at the latest beginning on next week.

 

So, they have to take the dashboard out, and start working on it today. They told me it will be done Friday, if mot then Monday.

I told him I’m very concerned about taking it out and having future problems with the dashboard, for example the screen, or buttons that don’t work, or the ambient lighting. They reassured me that everything will be put back exactly the same, and everything will work, and I will not even realize that the tech was in there. Has anyone experienced any issues with removing the dashboard at the dealership?