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1999 E320
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56 Posts
Discussion Starter #1 (Edited)
Need help to solve 1999 E320 AC problems

Hi. A few weeks ago I had a problem with my AC. I charged it up with a can of R134 and was fine until last Friday. I lost my AC which is no good at this time of the year in Las Vegas. I checked the pressure by connecting my pressure gauges. Engine idling, temperature on both sides set to Lo, fan at full blast, outside temp this morning was 77. Low pressure side 35 psi, high pressure side 195 psi. Air at passenger side vent cold, driver side not so cold and getting warmer. After a few minutes both vents have warm air and getting hot. At that time pressure on low side jumped to 110 and pressure on high side dropped down to about the same. I took apart the duo valve but it was clean inside and both pistons and O rings in good condition. Voltage on both solenoids was the same, 13V. This means both valves are closed, no hot water going to the heaters. I went through the AC diagnostic and this is what I got on the AC control unit display:
1 - 91
2 - 78
3 - 87
4 - 80
5 - 138
6 - 186
7 - 14
8 - 139
10 - 6
11 - 3
12 - 3.3
20 - 7.8
21 - 42
22 - 00
23 - 32
24 - 13.1
40 - 164
41 - 32

Would anyone tell me what is going on with my AC system ? I suspect a bad expansion valve. Thank you.
 

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Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
what fault codes ?
 

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Registered
1999 E320
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56 Posts
Discussion Starter #3 (Edited)
Sorry that I forgot to mention that there were no fault codes. So, I decided to order a new expansion valve and a new receiver dryer. It is a 13 year old car and these are mechanical components that should be replaced anyway. As far as I know there is no fault codes for a bad expansion valve. What do you think ?
 

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Registered
1990 Mercedes-Benz 420 SEL(RIP),1997 Mercedes-Benz E420
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1,936 Posts
I thought a leak or low freon would cause an ac compressor clutch code to appear....
 

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Registered
2001 E430 4matic
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419 Posts
It could be the expansion valve based on your readings.

#5 (evaporator temp) reads 138 and #8 (refrigerant temp) at the Rec/Drier also reads 139. With #7, 14 bar, your # 5 should read 45-35 degrees and it dosen't or at least being on the colder side depends on how long engine was running. Everything else looks normal, but your evaporator is hot. As you mentioned it worth to change Rec/Drier and the expansion valve.
 

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Registered
1999 E320
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56 Posts
Discussion Starter #6
Thanks for your feedback. I will post the what was the cause of my problems when my AC starts working again.
 

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Registered
1999 E320
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56 Posts
Discussion Starter #7
Finally, I got my AC working. Replaced the expansion valve, receiver dryer, and evaporator temperature sensor. Vacuumed the system and filled it with fresh refrigerant and oil. Works great in this Nevada hot summer.
 

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Premium Member
2009 E350, 2007 E550, 2001 S500
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180 Posts
I just replaced the ac compressor on my 2000 E320 with one that I had previously taken off a car my wife totaled. The replacement compressor was less than a year old and had been stored properly for 18 months. I also installed a new receiver dryer along with it. After installing the comp and r/d I pulled a vacuum on the system and let it sit for two hours with no bleed down or leaks. I recharged per spec and reset the ac fault codes, the ac worked perfectly with ice cold air for three weeks. Today I jumped in and took off but the ac didn't blow cold, only outside temp air. Yesterday it worked fine.

Here are the numbers:

The EC light is NOT on.
The AC Clutch will not engage.
The Low Pressure reading while running with ac on is 110 psi. (It read 38 psi just after I recharged it.)
The High Pressure reading while running with ac on is 150 psi. (It read around 280 psi when recharged.)
The only fault code is E 1419.

Here are the readings with car running in 84 degree heat:
1 100
2 84
3 107
4 107
5 103
6 181
7 07
8 91
9 30
10 4.5
11 2.8
12 4.2

Does anyone have an idea where to start troubleshooting?
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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6,674 Posts
is this with the engine running ? It woul dbe much better if you put the FUL list here so we can see the battery voltage and the rpm information too.

If running, you are low on refrigerant. At idle #7 should read 14 to 15 bars.
 

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Premium Member
2009 E350, 2007 E550, 2001 S500
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180 Posts
Yes that is with the engine running. What do you make of the High and Low pressure readings that were obtained with ac gauges?
 

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Premium Member
1998 E320 base sedan @ 160kmiles
Joined
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6,674 Posts
The low side and high side pressures (110 and 150) are close to each other confirming that your compressor is not running or intermittent. Interesting that the high side reads 150 psi which is a bit more than 10 bars, and the #7 is 7 bars. But this is not the main problem. You have a clutch error code and if it does not clear (comes back after running the a/c), I would check the center hub of the compressor while it is switched on and off with the EC button (EC with red LED is compressor OFF).

Once confirmed that the compressor is not turning when it is supposed to, the problem is likely to be a burnt clutch fusible link inside the clutch. I think the a/c controller check the voltage to the compressor clutch in the EC mode as well as A/C on mode, and determines if there is an open circuit. to the clutch coil. I guess you could check continuity between the compressor electrical input terminal and chassis ground. It should not be open or high resistance.
 
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