[mdsjsb]

First let say this is a fantastic site. I see others with similar problems and just tell me to look harder if someone has already answered these questions.
The A/C on my MB E320 (Year 2002) is no longer blowing cold air. I ran a diagnostic and collected the data and am looking for some insight.
Followings are raw data I collected from the tests (EC was OFF while running the diagnostics):The first column restarting after setting for about 30 minutes after 20 mile drive. The second column is after engine running in driveway for 10-15 minutes. The third is immediately after taking a 10 minute highway drive and pulling over at exit to record the numbers.

Sensor 1 (Inside Temp): 75 80 76
Sensor 2 (Outside Temp): 66 76 66
Sensor 3 (Left Heater Core Temp): 96 82 78
Sensor 4 (Right Heater Core Temp): 94 80 69
Sensor 5 (Evaporator Temp): 69 82 80
Sensor 6 (Engine Coolant Temp): 177 199 188
Sensor 7 (Refrigerant Pressure): 05 07 04
Sensor 8 (Refrigerant Temp): 71 94 67
Sensor 9 Not used??? 31 31 32
Sensor10 Blower Control Voltage: 1.4 1.3 1.3 varied 0.0 to 6.0 based on fan
Sensor 11. Emission Sensor: 2.2 2.2 2.1
Sensor 12. Sun Sensor: 3.6 3.4 2.8
Sensor 20. Control Current Aux Fan: 3.2 3.2 3.2
Sensor 21. Engine Speed: 42 42 40 varied upto 66 while cabin tac read 2500
Sensor 22. Vehicle Speed: 0 0 0 road test about 2mph above speedometer
Sensor 23. Terminal 58d: 32 32 32
Sensor 24. Battery Voltage: 13.5 13.5 13.5
Sensor 40. Software Status: 164 164 164
Sensor 41. Hardware Status: 91 91 91
Sensor 42. ???: 40 40 40
Sensor 43. ???: 136 136 136

2. DTC Error Codes:
Error B1234 (Sun Sensor Malfunction)
Error B1416 Coolant Circulation Pump (M13)
Error B1417 Duovalve (Y21y1) left
Error B1423 Switchover valve block (Y11)

From what I have read on this site it appears that my 134a is low, If that is true, can I add it with the outside temp being about 65 or should I wait for warmer weather?
How does the engine speed number relate to the tach number that shows on the dash?
Sensor9 appears to have some value in it. Is it really not used on this vehicle?
Finally, there are some letters and numbers in parentheses, example: B1417 Duovalve (Y21y1) left. What do they stand for?

Any help is greatly appreciated. Great site.
John

 

[Matt L]

#7 is low and so is #8. Two things can cause this, the most obvious being low refrigerant. The less obvious reasons are a restriction in the system or a failed compressor.

With the engine running and EC illuminated, note the readings at #7 and #8. Then engage the compressor and note the readings again. If they decrease, you likely have a restriction in the condenser or dryer. If they stay the same, you may have a restriction at the expansion valve or bad compressor valves. Of course, both of them should increase upon compressor engagement.

Using a real gauge on the high side is recommended, to see if that matches what you see on reading #7.

 

[mdsjsb]

Matt,
Thanks for the suggestion. Here are the numbers I got when doing the test you suggested. With the engine running, placed the control in actual value display mode. Set the "EC" light on, read as follows, sensor7 = 06 sensor 8 = 87. Then turned the "EC" off read as follows, sensor 7 = 07 sensor 8 = 89.
You mentioned that the most obvious cause might be low refrigerant. Since my numbers DO NOT follow the other two possibilities, Do you think I should try a charge?
John

 

[Matt L]

If your low side is very low when the compressor starts, you are definitely low on refrigerant. I would expect #7 and #8 to raise more dramatically, but it's not hot where you are right now.

It is hard to judge the refrigerant level when the ambient temperature is low, so don't go overboard.

It would be a good idea to get a gauge set so you can monitor both sides while adding refrigerant. After you add some, let the system stabilize for about ten minutes before adding more.

 

[ohlord]

Run

the diagnostics at the settings and temps directed on
How to Diagnose Air Conditioning Malfunctions | EclassBenz.com
punch in the values (you only need 1-8) and the errors and it will at least give you a good starting point.
ohlord:bowdown:
write down the error codes and clear them when you are done.

 

[mdsjsb]

If your low side is very low when the compressor starts, you are definitely low on refrigerant. I would expect #7 and #8 to raise more dramatically, but it's not hot where you are right now.

It is hard to judge the refrigerant level when the ambient temperature is low, so don't go overboard.

It would be a good idea to get a gauge set so you can monitor both sides while adding refrigerant. After you add some, let the system stabilize for about ten minutes before adding more.

MattL:
I am holding off my recharge for two things, 1- trying to get a set of gauges. Second with the high temperature today of 55, and not expected to get any warmer before early next week, I'll wait till the temp outside is at least in the 70's. Thanks for the help, I will report back on my progress.
John

 

[NOLA430]

First let say this is a fantastic site. I see others with similar problems and just tell me to look harder if someone has already answered these questions.
The A/C on my MB E320 (Year 2002) is no longer blowing cold air.

Sensor 1 (Inside Temp): 75 80 76
Sensor 2 (Outside Temp): 66 76 66
Sensor 3 (Left Heater Core Temp): 96 82 78
Sensor 4 (Right Heater Core Temp): 94 80 69
Sensor 5 (Evaporator Temp): 69 82 80
Sensor 6 (Engine Coolant Temp): 177 199 188
Sensor 7 (Refrigerant Pressure): 05 07 04
Sensor 8 (Refrigerant Temp): 71 94 67
John

To test your a/c in cold weather (outside temp 66 degF) you have to set the cabin control setting to less than 66 or the duo valves will open to let hot air flow out of the vents. Wait for a nice warm day, say 72 degF plus, readjust the cabine temperature to say 65 degF and repost your readings.

 

[mdsjsb]

continuing with testing for No Cold Air

If your low side is very low when the compressor starts, you are definitely low on refrigerant. I would expect #7 and #8 to raise more dramatically, but it's not hot where you are right now.

It is hard to judge the refrigerant level when the ambient temperature is low, so don't go overboard.

It would be a good idea to get a gauge set so you can monitor both sides while adding refrigerant. After you add some, let the system stabilize for about ten minutes before adding more.

The day is a little warmer finally, about 73
I got my hands on an ac manifold gauge so here are my results.

Sensor 1 (Inside Temp): 96
Sensor 2 (Outside Temp): 73
Sensor 3 (Left Heater Core Temp): 93
Sensor 4 (Right Heater Core Temp): 93
Sensor 5 (Evaporator Temp): 93
Sensor 6 (Engine Coolant Temp): 191
Sensor 7 (Refrigerant Pressure): 05
Sensor 8 (Refrigerant Temp): 71
Sensor 9 Not used??? 31
Sensor10 Blower Control Voltage: 5.6
Sensor 11. Emission Sensor: 2.7
Sensor 12. Sun Sensor: 2.6
Sensor 20. Control Current Aux Fan: 3.2
Sensor 21. Engine Speed: 44
Sensor 22. Vehicle Speed: 00
Sensor 23. Terminal 58d: 32
Sensor 24. Battery Voltage: 13.5
Sensor 40. Software Status: 164
Sensor 41. Hardware Status: 91
Sensor 42. ???: 40
Sensor 43. ???: 136

2. DTC Error Codes:
Based on what I read in one of the posts I cleared the DTC codes that I had, there were 4 of them, as I described in my original post.
I now have the following
E
E FF
If the codes I cleared were indicating a problem how long should it take for the codes to reappear? It has been 4 days since I cleared the DTC codes.

The Gauge has the following readings.

LOW HIGH
PSI 30 75
Bars 1.5 24.9

As I was under the hood connecting the high and low, taking readings, and checking that the compressor was engaging and disengaging based on the “EC” light on the Climate control, I have heard a sound (like a clicking or spark plug arc) coming from a part on the drivers side inside top wheel well. I does it for awhile and then stops. I am attaching a picture of where I think the sound is coming from. Could this be part of the problem?

 

[Matt L]

Your high-side readings in bar and PSI are inconsistent. What's the real reading there? 75 PSI is probably too low (I will have to consult the chart) while 25 bar is much too high for that ambient temperature.

The clicking part is part of the emissions controls and clicks all the time on all of the gassers. It's not related to the climate control.

 

[NOLA430]

Sensor 7 at 5 bar is too low. Add refrigerant.

 

[Matt L]

Assuming that the high side is at about 5 bar (what is the real value here?) and low side is at 1.5, he would appear to be low on refrigerant.

Assuming 40% humidity and engine at 1500 RPM, windows or doors open, fan on max and both sides set to LO, center and side nozzles opened, the correct pressures would be about 7 bar high side, 2.1 bar low side. The center nozzle air temperature should be about 5C or 41F.