Tommy-C

Att: Techs....

I have a 1997 E-320. The air conditioning is not working... The economy light stays on and can not be turned off. A mercedes tech told me that the refrigerant needs to be refilled and another tech told me the control unit is bad. One day i turned on my A/C and i heard a hissing noise. How can this problem be fixed? Can someone help me? What parts are needed?

E430NEsilver

I had a problem where AC would engage briefly when the car is started but then stop working (fan worked and blew out ambient temperature air). There was no refrigerent leak.

I was worried about having to replace the evaporator (supposedly a big-time labor charge) but it turned out to be a <$60 plastic temperature sensor of some kind. My independent shop guy told me that this part is a somewhat common failure in the E class.

Luck.

Not a tech guru by any means...

fast_car

By any chance do you know the P/N of the temperature sensor ?

Thanks

E430NEsilver

The item number shown on the repair sheet is 210-830-0772 ("Temperature Sensor") with $60 cost. Don't know if this is MB number or independent shop's own. Luck.

lexrex

fast_car,

Your problem is most likely a faulty evaporator temperature sensor. Have you run the diagnostic to check the codes and actual sensor values? Post all the codes and post sensor values #3, #4, #5, #7 & #8 with the engine & A/C switched on.

Here are the instructions to access the diagnostics:
http://www.continentalimports.com/ser_ic40142.html

fast_car

Here is the code from my 1999 E320 with the engine & A/C switched on.
Does it mean I have a bad evap temp sensor, where is this sensor located ?

Thanks

The AC temp was set as 72 per instruction and car was park in side garage while I took this value

1 = 75
2 = 73
3 = 80
4 = 78
5 = 143
6 = 85
7 = 06
8 = 76
9 = 27
10 = 1.1
11 = 0.3
12 = 4.3
20 = 3.2
21 = 32
22 = 00
23 = 32
24 = 11.6
40 = 164
41 = 85
42 = 40
43 = 136

lexrex

The problem is without a doubt your evaporator temp sensor. Your evaporator temp sensor (#5) is indicating 143 degrees, which is clearly impossible given that the outside air temp is 73 degrees and your left & right heater (#3 & #4) core temps are 80 and 78 degrees respectively.

The system thinks your A/C temp is 143 degrees. It's blowing ambient air because the outside air temp is much cooler than 143!

The system ignores the evaporator temp sensor data for the first 10 minutes of operation. The fault is characterized by your A/C quitting 10 minutes after the ignition is switched on.

I believe the sensor is installed in the airflow behind the evaporator case. Not sure how to access it. Maybe someone else can help with this. I had a shop replace mine; labor was minimal.

fast_car

I bought the new sensor and now have to find where is located, I remove the panel under streeing wheel, but still can not find it

Can some one point where to look for

Car is 1999 E320

Thanks
Tan

HTBenz

I just had the same problem and had it fixed. I wish I would have had him point it out to me then I would be able to give you directions.

JimE430

If the hissing was comming from the center vent area, it could be the Expansion valve #202-830-01-84 This is common and I beleive you need to remove dash to access it.

Gomez153

anyone know how to install this?

JohnAMG

My wife;s 2002 E55 air condition is not cold at all too. I just ran the diagnostic and got these code,

1=76
2=75
3=75
4=67
5=73
6=152
7=06
8=82
9=31

I found #6 sensor is call ECT Sensor and the number seems high. What is ECT Sensor? And is this the problem? Any suggestion will be greatly appreciated.

John

lexrex

ECT = engine coolant temperature; 152 means your car is partially warmed up

#5 is your evaporator temp sensor. This should be in the 30s, not ambient. So, the car agrees with you that the air isn't cold. #3 & #4 are the temps of your left & right sides respectively.

#7 & #8 are your refrigerant pressure and temperature. #7 varies depending on how much compression is needed to cool your car. #8 always needs to be more than outside air temp (#2 = 75) to move heat from inside your car to the great outdoors. It is higher than the outside temp, so it looks like your A/C is working, but just barely.

You're probably low on refrigerant. Any hissing noises from the center vent? Is the passenger side center vent cooler than the driver side center vent? Oh, and the EC light is off, right?

JohnAMG

I didn't notice any hissing noise and the EC light is off. I will double check this afternoon when I get home. I suspect the refrigerant is low too. Thanks for your repsonse.

John

MARK CUMMINS

The A/C Evap Temp sensor is located at the Evap housing..look from the drivers side underdash..towards the center of the dash..cant miss it...also look at the replacement sensor..that WILL Help you locate the sensor

Gomez153

pic anyone?

JimPurdy

LEXREX,

Thanks for the explanation of the values. I have the printout but your explanation is much better.

E320

You're low on Freon the value of #5 should be between 14-17 bar (running engine and depends on ambient temp).

lexrex

14-17 bar is possible on a really hot day, but you're unlikely to see pressures that high when it's in the low to mid 70s. Our A/C compressors are variable displacement, which helps with efficiency. This means they compress the refiregerant only as much as necessary to bring the evaporator temperature below 40 degrees.

You might also notice that your right side (#4) is quite a bit cooler than the left side (#3). When both sides are set to the same temp on the climate control, and the right side blows colder, this is symptomatic of low refrigerant.

JohnAMG

OK, today I heard a hissing sound from the center dash vents. I hope my Mercedes extended warranty will cover this problem.

John

MG

What does the hissing noise canote? My AC stopped working 2 weeks ago and yes I heard a hissing noise when I tried to turn it back on again today

Edit - I pulled the codes from my car. They look to be in Celcius.

1 40
2 28
3 33
4 33
5 57
6 65
7 03
8 37
9 05
10 4.5
11 2.1
12 4.0
20 0.0
21 00
22 00
23 00
24 11.4
40 71
41 34
42 72
43 152

Error codes

Eb1234 <--- Sun Sensor, how would this failing affect my AC and whats the part replacement cost?
E FF <---- No idea what this means.

JohnAMG

Finally the AC is fixed under warranty. A pipe line(210-830-46-15) was leaking and drained all the refrigerant, and I was told the hissing sound came from the empty refrigerant. The tech. also replace the tank(210-830-04-83) and if it was not for the warranty I would be out $500 dollars.

John

lexrex

Glad you got it fixed under warranty. The sun sensor is located on the top of the dash near the center. It detects the intensity of sunlight coming in the windshield. If there's strong light, the sensor signals the climate control computer to upregulate the fan speed a notch or two to compensate for the heat from the sun.

jfoscue

I have a 2001 E320 that makes a hissing sound when I turn the A/C on. I can't remember all my diagnostics readouts but I remember #7 being 05. Is this low for the freon? If so what should that number be?

Thanks

Big J

if you over charge a refrigaration in a cars A/C will this blow hot air in the car as i try to recharge my e430 yesterday and now i'm having a reading of :

01=123
02=141

03=116
04=116
05=154
06=200
07=E
08=130
09=27

i just hope i did not mess up thing i have not since this numbers here