jherm

It has dropped to the 40s in temperature here in Atlanta and I'm finding that with my climate control set to auto and interior temperature at 75 that the car doesn't really seem to be blowing heat like it should be at that temp disparity (outside vs inside). I have to take it off auto and put the manual fan level up to 6 or 7 before I feel hot air coming out. At first I thought perhaps the car takes a bit to warm up and circulate hot air, but it seems to be doing this even after I've been in the car for a while and it is warmed up.

Am I missing something in how the auto fan level should operate or why am I not really getting hot air when in auto mode?

alyshehata

I've noticed the same thing. In my case, I found that switching the circulation mode to only be pointed at the driver (i.e no foot or windshield heating) fixes it no matter what fan level it is. It seems to be some kind of bug or bad design since I'm assuming it is sending a lot of hot air to the wind shield rather than to the passengers when on auto.

ManiacGT

I don’t find the ventilation system in the C that good. Auto is really more like off half the time. It allows the window to mist when damp outside (my bmw detects this and clears the screen without my intervention) it’s also errs on low speed fans etc

given it’s the wagon, it’s routinely cold in the back and warm in the front or vice verse.

poor. Is this normal for mercs?

jherm

I'm wondering if it has to do with the air distribution settings while on auto. i feel basically no air coming out of the center vents when on auto, but a little on the side vents (by the doors). perhaps when on auto it just routes most air to the sides and windshield?

Crankster

Mine seems to warm up nicely set on auto - AC when it is cold. I almost think there is a supplemental heating going on for the first few minutes. I know my VW oil cars have this, it comes in handy when it is really cold out.

StanNH

I live in a very cold climate, and the auto climate control works fine.

gfmohn

[QUOTE=jherm;7310607]... I have to take it off auto and put the manual fan level up to 6 or 7 before I feel hot air coming out. ...]
I routinely have to take it off auto when the cabin is still cold and indeed push the manual fan level up to 6 or 7. Also, the center vents are never on when heating on auto.

ItchyTasty

This is also what happens with mine, no air from the center vents on auto. I'm going to bring it up to the dealer and have them check it out. I thought at first it might depend on the dynamic control you had selected (i.e. eco setting also sets the climate control in eco mode) and thought that might explain it, but I tried it o eco, comfort, sport, and no difference.

Mikey53

+1 I don't live in a drastically cold climate but mine works fine in AUTO. Heat comes from the foot wells mainly just as I would expect. Who wants hot air blowing in their face?

ItchyTasty

You must be unfamiliar with the adjustments on the vents which let you direct airflow.

jherm

I'm actually bringing mine into the dealer tomorrow so will let you know what they say. I'm guessing this is how the auto function works and it's just set up in a really ineffectual manner as far as air distribution and intensity. My BMW was tremendous at warming up the cabin quickly in cold weather. If I didn't move to manual adjustments in the MB, it would not warm up at all in the car before I got to work on my 20 min drive.

Does yours also turn the AC on when you set to auto even when it's 40+ degrees colder outside than the interior temp is set to?

ItchyTasty

Please do let me know what they say. Not sure about the A/C, I'll check though.

DapperStyle

jherm

Ah, that makes sense.

AAN

jherm

Just got back from the dealer. They ran sensor/fan tests as it seems like the issue would be that an interior cabin temp sensor wasn't recognizing the right temp leading to poor operation. The tests said no issues. They also had a software update specifically relating to the climate control, but that didn't change this operation at all.

Basically they said that this is just how it is and that this generation C Class has really crappy / useless auto climate control. That's a hard answer for me to accept given that this was a standard feature on much lower end cars like 30 years ago. Spend $60k on a car in 2016 and it doesn't have functioning auto climate control?

here's another thread I found that basically had the same discussion and result...that this car doesn't have usable auto climate control: https://mbworld.org/forums/c-class-w...auto-mode.html

Mikey53

Mine works fine.

jherm

I wish we could drill down a bit more on the various comments in this thread stating theirs works fine. I wonder if part of this is different expectations on how the auto climate control should work and/or different conditions that people are experiencing when their auto is or is not kicking in the heat.

Here's my experience.

Lately, my car exterior temp gauge reads anywhere from 30-45 degrees when I get in to go to work in the morning. The interior cabin temp is set to 77 and on auto. So there's a good 30-40 degree difference between exterior temp and the target temp. The interior temp may be a little warmer than the 30-45 degrees the car reads for exterior temp, but it wouldn't be much warmer as the car is parked in an open air garage overnight. I now understand that auto will not really blow any air out of the center vents. That may be part of why I was thinking I had an issue. I would definitely prefer air to come out of the center vents and get warm air on my freezing hands. But I get that some may not like the hot air blowing out of those vents at them. But even at the 30-40 degree difference between exterior temp and target cabin temp, I'm not really hearing any hot air coming out of other vents and not feeling it get warmer. I've given it a bit of time thinking that maybe it won't really blow hot air until the car is fully warmed up. But nothing really ever seems to happen. Perhaps I'm giving up too early and going to manual mode? But I wouldn't think it should take 10+ minutes for heat to really start blowing.

So people that are saying theirs works...you're saying that when interior temp is set a decent amount higher than external temp, when set on auto, it kicks in heat fairly quickly after turning on the car and you can hear it coming out of other vents and feel it getting warmer within minutes? I'm not sure where else to go with this since there are several people saying theirs works, several saying their auto doesn't really work, and then I've got the dealer saying they ran diagnostics and my car has no issue and it's just that the W205 has a really crappy auto climate control function.

Crankster

I'm glad my generation C is not affected by this. I lever mine set on 72 - 73, Auto with AC all year round. I can drive maybe 1 - 2 minutes and I can feel warm air coming out. This leads me to believe the car has auxiliary heat like my VWs had.

StanNH

Except when I'm using the defroster, my climate control is left on auto. Summer temperatures here can hit 100F, and winter can drop to 30 below zero F. Right now, it's 11 below zero F. I typically leave auto set on 68-72, depending on outside temperatures. Rear vents are usually left open, and all front vents are open. After the engine warms up, the car is always comfortable in the winter. In the summer, the A/C does a fine job. That sums up my experience .... no drama, no complaints.

radiojon

Every car that I've owned that has an "auto" temp setting behaves this way when you first enter a cold car. The engine needs ample time to warm up before heated air can effectively come through the vents. The auto temp sensors in the car know that blowing cold/cool air (especially if you have it set to a very high temp setting like 75/80) from the vents won't effectively warm the car any faster, so it takes a while before the air coming through the vents is warm enough that the system starts to crank up the fan blower speeds, which it does gradually as the engine temp rises. And since heat rises, the "auto" setting will almost always drive most of the heated air from the floor vents and not from the upper vents. I guess it's the most efficient way for the system to operate. Of course, in summer, when the car is HOT and the "auto" setting wants to cool it quickly, as soon as the A/C compressor kicks on, you get cool air. Doesn't quite work as fast the opposite way with heat.

joe72camel

its 30deg Centigrade here and i tried to turn the temperature up to full. like op stated, most of the hot air comes out from the footwell(~70%) and the side and top vents, very little air comes out from the 3 center vents.
guess this normal operations.
doesnt matter to me as i would never use and no use for the heat function where i am. i'm just testing op's experience and sharing.