Fan Problem

[JRC]

Actually I don't think I have a fan problem. It is probably the sprinter system that diverts the air to the vents. This is a 2013 Interstate. About three days into a Michigan to Vermont color tour, I noticed the air conditioning had stopped coming out of the dash vents and the van was heating up. (85 outside). The fan could still be heard running and responded to the fan control to speed up and slow down, but still no air from the vents. Tried heat with the same results. Drove about an hour with the windows open, arrived at campground, checked fuses and still no air at vents. Worried all night about returning home to Michigan with no air, heat or defrost. Next morning everything worked until about 4 that afternoon when air stopped again. (Fan still sounds like it is running like normal). An hour later the air returned to normal by itself and worked all the way back to Michigan. What do you think? Drive till it fails for good? Let Mercedes troubleshoot? Hit it with a hammer?
Randy

[73shark]

Was the A/C compressor lite lit?

Did you try changing the vent selection rotary knob to see if it had any effect?

[Protagonist]

If the fan is running but no air is moving, first check the air conditioning intake filter. When you open the hood, it's in the open bin-shaped housing on the passenger side (the hood itself is the housing's lid). If the filter is clogged, no matter how hard the fan blows, no air moves.

Next check the A/C settings. There is a "recirculate" button on the dash; selecting it bypasses that filter and sucks air from inside the van instead of conditioning outside air. That mode will not stay on all the time; it will only last for about an hour or so before it resets to drawing in outside air. It's an air quality thing, because the Mercedes air conditioner doesn't recognize that you have a roof vent to provide air exchange and avoid oxygen depletion of the interior air.

So, my guess is that you have it set on recirculate, and it runs fine, but when it switches to drawing outside air, a clogged filter prevents it from drawing any air. Thus you get an intermittent problem.

Best I can do off the top of my head. Too bad my bald head is made of Teflon so nothing sticks, otherwise I'd probably have more ideas.

[joemikeb]

It sounds as if something in the A/C ducts is coming adrift and blocking the ducts such as the dust/pollen filter in the intake plenum under the hood or even something blocking the intake into the plenum. I have seen a loose piece of hood insulation do that in a Cadillac. I am not a mechanic so anything beyond that I would leave to the tender mercies of a trained Mercedes Benz mechanic.

[73shark]

If it returned to normal on the trip home, probably not a clogged cabin filter.

When set on the floor vents or defroster vents, still no air flow?

And the recirc time-out is 30 minutes which is a PITA on really hot days.

[avanti]

The same thing happened (only once) in our 2014 4-cylinder. It happened with the temperature in the high 80s on I-40 in New Mexico at the end of a very long uphill haul at high speed. Fixed itself shortly after we got off the highway onto a lower speed road. The engine temperature was normal, but I kind of assumed it was some kind of overheating of something or another.

[Brucet45410]

I had a similar action. My belief is that you have the temp set too cold - and are asking it to cool too fast. I believe that there is a note in the operators manual saying that you need to make temperature changes slowly.

[JRC]

Thanks for the suggestions. I'm going to print this page and try them next time the problem reappears.

Randy

[jdalrymple]

It could be the evaporator freezing up. The ice blocks the air flow through the coils.

This can happen for a varitiety of reasons, but to test the theory, the next time it happens turn off the AC compressor and run the system in vent mode with the fan on high. This forces air through the same path as the AC, but without refrigerant freezing the evaporator coil.

If ice is the problem, the air flow will melt it and return to normal in a few minutes.


I have seen this on high humidity days when running the AC for extended periods. As ice begins to form, it just keeps building up.

Regards,


JD

[PSchw]

I had the same. It would do it and then would go away. after several weeks it would do it again. I put it to MB for service and had them check out the A/C say cam back that the freon was low. The tried to top it off but it would not take anything they replaced the A/C compressor completely under warranty. Now i on have 500 miles but did not notice it. again before it would wok ok for several thousand miles before it would come up again.
Peter

[AtlantaCpl]

I'm betting it is the evaporator as Jeff says. Most of the time it is a weird combination of outside temperature, pressure, and humidity coupled with running the unit a long time that causes it - but it can also be caused by having the improper refrigerant pressure so you might want to get that checked.

Brian

[Boxster1971]

Originally Posted by Brucet45410

I had a similar action. My belief is that you have the temp set too cold - and are asking it to cool too fast. I believe that there is a note in the operators manual saying that you need to make temperature changes slowly.

I had the same problem last summer. Then I read some discussions on the complexity of the Sprinter HVAC system. Point was to set temp at level you want, like 68-70 deg and let the system do the rest. Since I've used this approach like operators manual says I've had no other problems in last year.


- - Mike
2013 Lounge EXT on 2012 Sprinter