simutx

I have a 2001 E430 with an intermittent air conditioning problem. From what I have read, it is best to post the values that the control unit is displaying:

Engine Cold (no ignition)
1. 80
2. 80
3. 89
4. 89
5. 87
6. 85
7. 08
8. 80
9. 27

Engine Cold (Engine Running)

1. 80
2. 80
3. 89
4. 89
5. 87
6. 87
7. 06
8. 82
9. 35

Engine Hot (Engine Running)

1. 87
2. 82
3. 89
4. 89
5. 87
6. 175
7. 20
9. 82

The values posted are with the a/c system not pushing out cold air at all.

Today, the a/c control unit did not display any trouble codes. However, two weeks ago (for the first time), the EC light came on and stayed on until I stopped the car. When I pulled the codes it revealed an EB1227, EB1231, and EB1241.

It also seems that I have to manually turn on the aux fan by pressing down the Auto buttons at the same time. That aux fan does not come on automatically.

When the a/c does work, it does pump out nice cold air.

Can anyone give me any indication of what the problem might be?

I suspect that I have a bad "Pressure Sensor" and potentially a bad "Aux Fan Controller".

Thanks,

Marc

Plutoe

1227=outside air temp sensor;1231=engine coolant temp sensor;1241 refrigerant level.

FYI 5 should be 41; 7 should be 15-17------you forgot 8 while hot and if 7 is correct at 20 then on this planet 8 has to be 157, however the cold relationship of 6 to 82 is correct
look to 1231 as a potential cause of he incorrect fan speeds
Get a set of gauges and post the H and L pressure readings and does the needle hold steady or fluctuate wildly!!

simutx

Plutoe,

Thanks for the response, I definitely appreciate it. I will go ahead and run over to one of the auto parts stores and check pressures.

I accidentally left 8 off while hot, but that reading is 82 with engine running.

Plutoe

You got a problem if 7 was 20, 8 should be 157-------smart idea---what do the gauges indicate.

kajtek1

20 bars of compression indicate that your system works, but something is cutting it off.
Your hot cabin temperatures are almost the same what cold values, so do 1 more test when entering car park in hot sun. Read the values before engine start, than leave #7 on display and start the engine seeing how the value changes for next couple of minutes.

simutx

Katjtek1,

Thank you as well for responding. I just ran the test as you asked, here are the values:

Car Parked in Hot Sun (Engine NOT Running):

1. 96
2. 94
3. 94
4. 94
5. 94
6. 118
7. 07
8. 93
9. 27

Car Running (Aux Fan Not Running)

1. 103
2. 100
3. 105
4. 107
5. 105
6. 190
7. 08 to 09
8. 120
9. 27

I then went ahead and turned the Aux Fan on manually by pressing the two Auto Buttons, here are those values:

-Everything was the same with the exception of the #7 reading which went up to 20

I then shut the car off and took more readings with the car not running:

-The only value that changed was #7 and it went to 10

kajtek1

Any codes? You have software issue as you smartly confirmed with overriding fans manually.
Would you keep the car in override, the 20 bars of refrigerant has to cool down the car, but it will take couple of minutes.

simutx

No error codes were shown after the last test

kajtek1

Electronic controls is what I hate as you can't troubleshoot them easy way.
I would try the old-fashion way of resetting by disconnecting the battery for few minutes.
What still makes me wonder how-come your park car shows almost the same temperature inside and out. Usually cabin get very hot when sitting on sun.

simutx

I left the windows open while I was doing this. It's 106 here in North Texas today! Unbearably hot...

Do you think I should just go ahead and replace the two sensors; Refrigerant Pressure and Temperature Sensor at the Receiver/Drier? I already have the pressure sensor.

I am going to try to attempt to do the high and low side pressure readings in the morning. I did get a set of pressure gauges this afternoon at the auto parts store.

This whole problem really does act like it's an electric/sensor issue. As a side note, I have already replaced the Engine Coolant Temperature sensor and the Evaporator Temp Sensor. I think the Refrigerant Temp and Pressure sensors are the last two that I have not replaced.

kajtek1

Your sensor calibration looks good so far and yes, the morning check can give it one more confirmation.
I think opening pressurized system should be the last resort.
As I said, I am not good in electronics, but knowing how cheap W210 parts are, I would be tempted to buy replacement climatronic on ebay.

simutx

I was able to get some gauges and check the low side and high side pressurization:

Car Off:
Low Side: 100 Psi
High Side: 100 Psi

Car On and A/C On

Low Side 80 Psi without Aux Fan On, 77 with Aux Fan On. Otherwise Pressures stayed the same, they were stable
High Side: 100 Psi



Also took some more readings from inside the cabin:

Cold (Car Not On)

1. 84
2. 85
3. 91
4. 91
5. 91
6. 85
7. 06
8 84
9. 27

Car On (No Aux Fan On)

1. 84
2. 85
3. 93
4. 93
5. 91
6. 123
7. 07
8. 85
9. 33

Car On (Aux Fan On by Depressing two Auto Buttons)

1. 84
2. 85
3. 93
4. 93
5. 91
6. 132
7. 20
8. 85
9. 33

kajtek1

20 bars = 300 psi, so was the 100 psi on gauge read at the same time?
With variable output compressor those values change in just seconds, that is why it takes persistence to fully troubleshoot it.
As I said above, observing pressure #7 after starting the compressor for couple of minutes would give some answers.

simutx

Kajtek1,

Yes the pressures were read at the same time.

kajtek1

I would double check it, but looks like your pressure sensor is giving false readouts. Never have heard about such failure, so even triple checking would not be too much.
You will have to empty the system for sensor replacement.

simutx

simutx

kajtek1

This has to be false reading as with car off, the pressure equalize (might take few seconds, but still).
Expansion valve has a filter in front of it, so since you will drain the system, getting new one would be good idea.

simutx

simutx

On the way home the a/c worked well after replacing the pressure sensor and vacuuming the old refrigerant out and replacing it. Crossing my fingers that I have found the issue but will know more in the coming days.

simutx

Well, unfortunately my replacement of the pressure sensor and vacuuming out the system did not work. The a/c system is still shutting off randomly and coming on randomly as well. Do you think I should replace the expansion valve, could that be the culprit?

So far I have done the following:

1. Replaced Engine Coolant Temp Sensor
2. Replaced Pressure Sensor (cleaned out and vacuumed system)
3. Replaced Evaporator Temp Sensor

kajtek1

I think you need to do proper troubleshooting.
There is too many inconsistencies in previous data to go back to it.

simutx

Any advice on what steps to take in troubleshooting this issue?

kajtek1

Look like a member on twin forum did troubleshooting.
With such data you can analyze the system.
https://docs.google.com/spreadsheets...vvreXSSD8/edit

simutx

I have added an Excel file for review