[deanobenz]

1999 E320 with 92K miles had not been started for a year as of early July 2013. Started E320, A/C runs but not cold enough. Added two can of 134A Freon, A/C is nice and cold. Five days later with car sitting, A/C quit.

As I set out to diagnose and repair A/C, I worked my way through mountains of pages on A/C including stickies and guides. I know I am going to need your help to resolve this A/C problem and I thought what If I could also contribute a systematic troubleshooting summary with links back to reference forum pages and guides along with pictures and diagrams as WE resolve A/C problem.

 

[Musikmann]

Did you check our sticky threads at the top of the page?

 

[deanobenz]

step 1: collect sensor data and trouble codes. with engine running and engine off. Reference:

Eclassbenz, W210 Air Conditioning Diagnosis | EClassBenz.com article
Forum stickies - Climate Control

             9/26                10/12           10/12
             engine             engine          engine
             running            off               running
1.          40                    37               37
2.          42                    30               30
3.          38                    29               32
4.          39                    29               32
5.          59                    55               55
6.          44                    25               34
7.          01                    00               00
8.          47                    28               28
9.          05                    05               05
10.        2.7                   2.7              2.7
11.        2.3                   2.3              2.3
12.        4.1                   4.1              4.1
20.        0.0                   0.0              0.0
21.        06                    00               08
22.        00                    00               00
23.        00                    00               00
24.        13.1                 11.0             13.1
40.        71                    71               71
41.        36                    36               36

Trouble Codes
           B1234?               FF               FF
           FF

I am not sure about B1234 code on 9/26 as I repeated test and it did not repeat.

FF trouble code refers to low on Freon. Refrigerant Pressure is Sensor 7 measures 00 bar. Low Freon started five days after 2x12 Oz cans were added indicating a freon leak in the system. What other clues do the senor and trouble codes point?

 

[Musikmann]

Eclassbenz used to host a nice site, I'm glad you found that. Does it still work?

 

[deanobenz]

step 2: Evacuate and fill to determine cause of freon leak.

Examining the entire climate control system.

My Quickie method:

1. manually squeeze low side port to let out ant remaining 134a refrigerant.
2. check both low and high side ports to be free of 134a.
3. Since I have access to a R12 leak sensor and since this R12 sensor is not sensitive enough to find 134a leaks, With the engine off, I elected to charge system with 60 psig ( approx 4.1 bar) of [highlight]R12 freon vapor[/highlight] not liquid via the low side port.
4. I then used my air blower and blew out air above and below front end to improve the sensitivity of leak test.
5. I tested using the leak tester probe every thirty minutes for the next two hours as follows:
   
   At the low port no detectable leak on probe
   
   At the high port no detectable leak on probe
   
   Around the compressor
   I got positive leak indication in the area around the compressor as shown below.
   
   
   .
   
   Around the condensor no detectable leak on probe
   
   Around the duovalve no detectable leak on probe
   I followed Duovalve removal and cleaning sticky.
   I cleaned the upper plate as shown below.
   
   
   
   I was not sure about lubricating the plungers when I found all this water around them see below. so I did not lubricate and put duovalve back together.
   
   
   
   
   Inside the air cabin filter housing - closest I can get to evaporator coil no detectable leak on probe
   
   I followed instruction here. Since I had to remove the cabin filters to drop my probe to test for freon leak, I went ahead and waterwashed the two cabin filters and laid them out to air dry before re-installing. see pic below.
   
   
   
   
6. I then squeezed out as much as possible of the R12 Freon vapor in preparation to purge with R134A.

Now I need more help:
what could a leak in the highlighted area around compressor mean?
Was my testing sufficient to rule out evaporator coil? if not how do I rule out evaporator coil?

 

[Kajtek1]

I got lost following those 20 or so actions you took, but your data chart clearly shows refrigerant leak and you have one pinpointed at the compressor
fix it and retest without worrying about heater valves at the time
Your battery and charging system shows weak - you can retest them later

 

[ddaddy]

Some of us have tried a quality stop leak successfully and it may help you if it's a hose seal. Red Angel is still working for me. GL

 

[Kajtek1]

Consider stop leak as last resort. I used it when after long troubleshooting figured out the evaporator has to leak. This is a part that takes LOONG time to access so worth the shot at it.
Leaky hose not likely will seal with sealer and being easy to access should be no problem to fix the right way.

 

[ddaddy]

... easy to access should be no problem to fix the right way.

Good point :bowdown:

 

[deanobenz]

Kajtek1, How do I pinpoint what to fix? The leak detection probe detected a leak below the round black edge as shown in the photo. Incidentally, the 6 year battery is new.

daddy, I will keep that red angel in mind if I can not find the actual source of the leak.

Sent from AutoGuide.com Free App

 

[Kajtek1]

Kajtek1, How do I pinpoint what to fix? The leak detection probe detected a leak below the round black edge as shown in the photo.

Wash it and recheck. Repeat if necessary.

 

[keyhole]

Ref #24. Something wrong here. 

New battery or not, those are not good numbers for your battery in the 2 conditions.

Why not put a DVM (testmeter) across the battery termimals and check there directly. You should see: a) engine running - about 14.3 volts. b) engine off - about 12.5 volts.

This has nothing to do with your a/c system performance.

 

[deanobenz]

Ketjak1, do you mean wash it with water and retest?

Keyhole, thslanks for sharing numbers, will test and report back.

Sent from AutoGuide.com Free App

 

[Kajtek1]

read the label on dye you have used. I believe most of them are water-washable.
Wrapping the hose with paper towel in the area you already know will make pinpointing easier.

 

[keyhole]

deano

Ref checking your Duovalves. To the best of my knowledge, the duovalves are solely for the heating system, and refrigerant pipes goes nowhere near that item.

See the WIS coolant circuit below. (I know it says that is for engine M113 in W209, but it is identical for the M112 in your E320.

I cannot identify the item where your leak is coming from. The complete refrigerant path is:

compressor - high press hot gas to:
condenser - high press hot liquid to:
receiver/dryer - high press hot liquid to
metering orifice - low press cold liquid to
evaporator - low press cold gas to
expansion valve - low press cold gas to
compressor. .