Hi,

I have a 98 E330 TD and I am having a strange A/C issue. When I turn the air on it works on the passenger side, but blows hot on the drivers side. I took it to a local tech who told me that it was the controller in the dash, so I replaced it, and I still have the same problem. There is plenty of refrigerent in the system, and as I said, the passenger's side blows cold. Any help would be appreciated.

Orlando

My money says the tech was not a Mercedes tech. Not an uncommon problem. Probably a sensor or low freon level. Do a search - lots of similar problems like yours discussed.

Len

I would think Duo -Valve they are open by default. See the troubleshooting guide
http://www.continentalimports.com/ser_ic40142.html

YES, have the refrigerant evacuated & then re-charged to the correct level BEFORE spending any MORE $$$

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Wow,

I am surprised that after telling you that the level was checked and one side blows cold that 2 of you would recomend looking at the level or evacing the system. Are you saying it is normal for a system to blow cold on one side if the refridgerent is bad, since I know it's not low, it can only be bad (can it go bad) i guess. Also, Peter, I went to the page that was linked, great info, sadly, you were betting it was a duo-valve, and I don't see any test for that at all. Oh well,

Orlando

I was reading a document last night which suggested that low refridgerant levels cause drastically lower oil circulation in the system, with a lot of the oil remaining in the evaporator.

Do you suppose that the left side of this evaporator somehow holds a bunch of oil when the refridgerant is slightly low? Clearly the right side is not affected nearly as much.

MB Doc is saying that he doubts that you evacuated the system to measure the level. Otherwise you're guessing.

When the refridgerant level is slightly low on the 210, it does exactly what you describe. Since your symptoms EXACTLY match what we've seen with these cars, do you suppose that perhaps we're not talking out of turn?

Matt,

I never said anyone was talking out of turn, I said I was surprised. Point of fact, I never even said I wouldn't try it. As for the level, it was measured by the tech (no, not a MB tech, just an Import tech) and since I didn't pay for an evac and recharge, I am pretty sure he didn't do one. Now, I am only asking this to gain knowledge, so please don't take this the wrong way, but are you saying the levels are different then what they really are if you just measure them, and the only way to get a true reading is to evac the system and recharge it properly?

Thanks,

Orlando

That's what I'm saying. But I'm also saying that you're probably low. Low refridgerant causes the left side to output ambient air, with cold air on the right. A "feature" of this unit.

Have him check again, and remember that you can exceed the values in the charts by a specified ammount (it's on the same page as the chart in the diagnostic manual) if necessary. Adding a bit of refridgerant will probably quickly bring the left side down.

Matt,

Thanks, I will run the diagnostics and see what it says, and then do something about it accordingly. It would be nice if it was just low on refridgerent, as I could by a kit in an auto store for about 20-30 dollars and add some and it should blow cold again.

Orlando

Be sure to test the auxiliary fan (M4) as it will can kill your system if it is inoperational. Short version, to test, hold both AUTO buttons for more than ten seconds (takes about twelve on my car). The fans in front of the radiator should start. Holding both AUTO buttons for more than ten seconds turns them off.

OK,

I will try that as well, and report back on Monday. I am off to have my weekend, and test the a/c components!

Orlando

I had same issue, had dealer evac, and recharge system. Works perfectly, however they did find a leak at the compressor. Right now I am refilling when needed. The recharge by the dealer lasted about 6 weeks with minimal use of air. I am on week 2 with my own refilling via can from Autozone. I am hoping to get through the summer this way until I can get the compressor and drier replaced. Also, low pressure will cause the expansion valve to hiss, its a sure sign you are low on R134

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Dennis
2006 E320 CDI Black/Black Leather. Nav, HTD Seats HK stereo 32000 miles.
2000 VW Passat 1.8t 300,000 miles as of Dec 09, 2009 original owner
1997 E300d Silver 300,000 miles As of Jan 05, 2010
3rd owner SOLD

Unless you're losing oil from the compressor shaft seal, use pure 134a. Don't use the stuff with leak sealer or oil added, or you'll end up with too much oil in the system, or worse.

I am having a similar problem, but remember mine is a RHD car

http://forums.mercedesclub.org.uk/showthread.php?t=18124

I'd be interested on your input on this.