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1997 E420
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Discussion Starter #1 (Edited)
Hey guys, so earlier this year I had to recharge the A/C on my 1999 E320 after it had sat for several months. Everything worked fine after that for months, besides the new faint intermittent hiss that developed after I got the A/C working again, but it once again stopped working today.

My kid brother told me that it didn't work, that it would only kinda work when the car was moving. First thing I noticed was how quiet the car was and quickly realized that the radiator fan would not start under any circumstances. I then also attached the gauge and hose attachment that came with my all-in-one A/C recharge can and the dial reading was off the chart. Matter of fact the slightest touch of the trigger would release some of the pressurized air or gas. I continued doing it after watching some trashy videos suggesting one do so, and I stopped once it came back down to the green "FILLED" section of the chart, but A/C still didn't blow cold.

Then I proceeded to troubleshoot the radiator fan and discovered a wad of crispy ancient electrical tape on the radiator fan's wiring. It looked like the two wires shorted and came undone, but surprisingly the fan started working again after I cleaned and repaired that part of the wiring, but now the A/C still doesn't work even though the fan works now and refrigerant gauge reads "FILLED".

We test drove the car to AutoZone to buy a new can of refrigerant, and on the way found that the now that faint intermittent hiss I mentioned earlier is now a nonstop and more audible noise.

Should I proceed with a recharge like I did earlier in the year, or is the problem different now?

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1998 E320 base sedan @ 160kmiles
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Did you run the engine and a/c while charging ?

Did you check if the compressor is turning ? Check the hub of the compressor pulley with the a/c on while engine is running.

Did you check the sensor values, and fault codes from the climate controller menu ?
 

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1997 E420
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Discussion Starter #3
Did you run the engine and a/c while charging ?

Did you check if the compressor is turning ? Check the hub of the compressor pulley with the a/c on while engine is running.

Did you check the sensor values, and fault codes from the climate controller menu ?
I didn't charge it yesterday, I just used a leftover gauge I had lying around to check if maybe enough refrigerant had leaked out or something. That's when I noticed that pressure had built up beyond what the gauge dial could measure. I also used it to release the pressure as per some YouTube videos, and fixed the radiator fan which wasn't working.

Yeah the hub engages and turns as soon as I turn on the A/C.

There were no DTCs in the memory, I wonder if they get erased whenever I check and clear codes through the Bluetooth OBD2 scanner because I did that before checking for DTCs. There weren't any new or relevant codes.

Here are the readings I pulled first thing this morning.
1/76
2/80
3/80
4/76
5/76
6/139
7/5
8/75
9/30
10/6.0
11/2.4
12/4.1
20/3.2
21/44
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136

Here's a clip of the sound I'm talking about...

It's a lot more pronounced in the video, but still annoying. Back when I did recharge it in April it was just a faint hiss that would bubble up, but A/C was ice cold for months.

Should I try recharging it? What exactly was that pressure I was releasing yesterday if not refrigerant? The two gauges I used have similar readings though one shows borderline low...


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1998 E320 base sedan @ 160kmiles
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There were no DTCs in the memory, I wonder if they get erased whenever I check and clear codes through the Bluetooth OBD2 scanner because I did that before checking for DTCs. There weren't any new or relevant codes.
You read the climate control faults from the climate control menu


The DTCs from the OBD2 port are for the powertrain, and any reset you did will not affect the climate control faults.

Your readings indicate that the engine was running when you took the readings (13.3V reading indicates alternator charging the battery). I don't know how soon you took the readings, but the coolant temp shows 139 F which indicates engine was running for a while, so the climate control reading should be stable. If the compressor was running as you indicated when you took the readings, it is not compressing at all. It is 5 bars and the temperature of the refrigerant is 75F.

Take a measurement with the engine off for items 7 and 8 when the engine is cooled down (static measurement).

With you gauge connected. Note the low side pressure with engine not running. it should be around 75 to 80 psi. Then start the car with the a/c on. If the compressor is running, it should go down to 30 to 40 psi (the green region in your gauge).
 

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1997 E420
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Discussion Starter #5
You read the climate control faults from the climate control menu


The DTCs from the OBD2 port are for the powertrain, and any reset you did will not affect the climate control faults.

Your readings indicate that the engine was running when you took the readings (13.3V reading indicates alternator charging the battery). I don't know how soon you took the readings, but the coolant temp shows 139 F which indicates engine was running for a while, so the climate control reading should be stable. If the compressor was running as you indicated when you took the readings, it is not compressing at all. It is 5 bars and the temperature of the refrigerant is 75F.

Take a measurement with the engine off for items 7 and 8 when the engine is cooled down (static measurement).

With you gauge connected. Note the low side pressure with engine not running. it should be around 75 to 80 psi. Then start the car with the a/c on. If the compressor is running, it should go down to 30 to 40 psi (the green region in your gauge).
Thank you for clarifying, it read E/FF when checking for DTCs and doing the readings, that's why I thought that clearing codes through the OBD2 scanner beforehand must've done something.

I did see the hub engage with the pulley when toggling the A/C on and off, but i wasn't paying attention if it was engaged when taking the readings in the morning.

It's supposed to be 97F today, and it was already around 80F when I took the readings not sure if that skews things up. Also, my kid brother already used the car for errands after that, so should I just wait until tomorrow morning again for new readings?

I did do the test with the gauges when he came back from errands, and as you can see it's a lot more than the 75 to 80 psi with the car off. With the car and A/C on it comes down in line with the 30 to 40 psi you mentioned.


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1998 E320 base sedan @ 160kmiles
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The reading is way off when the engine not running. The rule of thumb is the psi reading should be around the same as the temperature reading of the refrigerant. So if the ambient is 90 deg F and you wait enough that the refrigerant temp is more or less equalized to the ambient (that you can check from the climate control sensor readings (item 8)), the refrigerant pressure should be about 90 to 95, and the high side pressure reading should be equalized to low side, and it should read about 6 bars.

If you read 150 plus at the low side when the refrigerant temp is 90, then you should get a proper manifold gauge. If the calibrated gauge still shows high readings, then something is blocking the pressure equalization in your system. In static state, the refrigerant pressure is "more or less" the same regardless you have 1 can or 3 cans in the system, as the refrigerant stays in the system in liquid form, and what you measure is the gas pressure that fills the remaining volume in the system.
 

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1997 E420
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Discussion Starter #7
The reading is way off when the engine not running. The rule of thumb is the psi reading should be around the same as the temperature reading of the refrigerant. So if the ambient is 90 deg F and you wait enough that the refrigerant temp is more or less equalized to the ambient (that you can check from the climate control sensor readings (item 8)), the refrigerant pressure should be about 90 to 95, and the high side pressure reading should be equalized to low side, and it should read about 6 bars.

If you read 150 plus at the low side when the refrigerant temp is 90, then you should get a proper manifold gauge. If the calibrated gauge still shows high readings, then something is blocking the pressure equalization in your system. In static state, the refrigerant pressure is "more or less" the same regardless you have 1 can or 3 cans in the system, as the refrigerant stays in the system in liquid form, and what you measure is the gas pressure that fills the remaining volume in the system.
So you're saying that this is something that simple can of refrigerant won't fix? lol

Okay, I'll buy a proper manifold gauge, but for some reason Amazon delivery times are a little delayed right now l...

So tomorrow morning for example, I note the ambient temperature, start the car, note all the sensor values, with number 7 (refrigerant pressure in bars) and number 8 (refrigerant temperature sensor) being of interest, and report back?

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1998 E320 base sedan @ 160kmiles
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Tomorrow morning, get the sensor values BEFORE start the car (ignition key in position 2), and then start the car with the a/c on, note the values again, and then check items 7 and 8 to see if there is any increase, and check if the compressor is running (10 mm bolt in the middle of the clutch must be turning, along with the clutch itself).

While you are taking the readings, also take readings from the gauge you have at the low side again with the engine not running and running.
 

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Don't fool around with cheap gauges, when you have precise gauge build into the car.
Solve the engine temp sensor like mrboca says before wasting time on bypassing the issue.
 

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Discussion Starter #10
Tomorrow morning, get the sensor values BEFORE start the car (ignition key in position 2), and then start the car with the a/c on, note the values again, and then check items 7 and 8 to see if there is any increase, and check if the compressor is running (10 mm bolt in the middle of the clutch must be turning, along with the clutch itself).

While you are taking the readings, also take readings from the gauge you have at the low side again with the engine not running and running.
Good morning, okay, so with ambient temperature at 66F and key in position 2...

1/64
2/66
3/71
4/71
5/67
6/73
7/04
8/67
9/27
10/6.0
11/1.2
12/4.3
20/3.2
21/32
22/00
23/32
24/11.4
40/164
41/85
42/40
43/136
E/FF
Gauge Picture 1

With engine on...

1/67
2/66
3/75
4/75
5/66
6/78
7/04
8/66
9/31
10/1.1
11/2.4
12/4.2
20/3.2
21/46
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136
E/FF
Gauge Picture 2

Here's a video of the hub and pulley. It looks like it's spinning since the bolt is not defined.



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you need to find explanation why your engine sensor shows 169F on 1 morning and 73 on following morning?
Your core sensors shows almost 10 degrees higher, than the rest.
Finally your system shows 4 bars = 60 psi, when your add-on gauge never shows such pressure.
How do you get such high inconsistency in your readings?
 

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1998 E320 base sedan @ 160kmiles
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Good morning, okay, so with ambient temperature at 66F and key in position 2...

1/64
2/66
3/71
4/71
5/67
6/73
7/04
8/67
9/27
10/6.0
11/1.2
12/4.3
20/3.2
21/32
22/00
23/32
24/11.4
40/164
41/85
42/40
43/136
E/FF
Gauge Picture 1

With engine on...

1/67
2/66
3/75
4/75
5/66
6/78
7/04
8/66
9/31
10/1.1
11/2.4
12/4.2
20/3.2
21/46
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136
E/FF
Gauge Picture 2

Here's a video of the hub and pulley. It looks like it's spinning since the bolt is not defined.



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Thanks for the readings. Since it is cold outside and inside (66), I hope the setting for the target temperature was LO LO. In any case, the evap core temp should have gone down with the compressor running and compressing. The gauge reading when engine is off should read about 60 bars, so it is out of calibration (or the pressure sensor is not reading correctly). I would wait for the proper manifold gauges connected to the high and low sides. That way, you will be able to see the high side pressure BEFORE the condenser and receiver/drier, not after (as the pressure sensor does). If there is a blockage in between, it will then be apparent.
 

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Having a similar issue on my 99 E320.

A/C Blows hot.

Is the Fan suppose to turn on when you turn the AC on like on other cars?
I'm getting code : B1459 Series interface (K2) connection to instrument cluster (A1) ... having a hard time isolating the issue
 

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1998 E320 base sedan @ 160kmiles
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Having a similar issue on my 99 E320.

A/C Blows hot.

Is the Fan suppose to turn on when you turn the AC on like on other cars?
I'm getting code : B1459 Series interface (K2) connection to instrument cluster (A1) ... having a hard time isolating the issue
You need to obtain and post the sensor values and fault codes (if any). The sensor values should be obtained with and without the engine running, a/c turned on.

If you have a single electric fan unit (between the radiator and the engine), the fan may turn on with the engine running, and turn faster if the high side refrigerant pressure is higher than 14 bars (200 to 210 psi). If the compressor is not running the fan will not run due to a/c. The code you have indicates that the pressure information is not communicated to the instrument cluster. If could be temporary, you could clear it and see if it comes back.
 

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You need to obtain and post the sensor values and fault codes (if any). The sensor values should be obtained with and without the engine running, a/c turned on.

If you have a single electric fan unit (between the radiator and the engine), the fan may turn on with the engine running, and turn faster if the high side refrigerant pressure is higher than 14 bars (200 to 210 psi). If the compressor is not running the fan will not run due to a/c. The code you have indicates that the pressure information is not communicated to the instrument cluster. If could be temporary, you could clear it and see if it comes back.
Got it. I will check the values and let you know what I find. Just got the car and learning quite a lot. Appreciate your insight. (y)
 

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Discussion Starter #16
you need to find explanation why your engine sensor shows 169F on 1 morning and 73 on following morning?
Your core sensors shows almost 10 degrees higher, than the rest.
Finally your system shows 4 bars = 60 psi, when your add-on gauge never shows such pressure.
How do you get such high inconsistency in your readings?
You mean 139F? I actually went through the readings twice at that moment, the first time it read 102F, and by the time I cycled back to it read 139F. Not sure what that was about, but I followed mrboca's procedures to the letter the following day.

Thanks for the readings. Since it is cold outside and inside (66), I hope the setting for the target temperature was LO LO. In any case, the evap core temp should have gone down with the compressor running and compressing. The gauge reading when engine is off should read about 60 bars, so it is out of calibration (or the pressure sensor is not reading correctly). I would wait for the proper manifold gauges connected to the high and low sides. That way, you will be able to see the high side pressure BEFORE the condenser and receiver/drier, not after (as the pressure sensor does). If there is a blockage in between, it will then be apparent.
I think that I set the temperature to 72 72... I followed what the STAR TekInfo link said. Anyway, I received the manifold gauge this afternoon. I'm going to watch a few videos on how to use it, but can you tell me what procedure you would want me to do tomorrow morning before the car sees any use?

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You mean 139F? I actually went through the readings twice at that moment, the first time it read 102F, and by the time I cycled back to it read 139F. Not sure what that was about, but I followed mrboca's procedures to the letter the following day.
139 right.
Such differences, assuming that you did not do misread indicate faulty sensor.
 

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1998 E320 base sedan @ 160kmiles
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You mean 139F? I actually went through the readings twice at that moment, the first time it read 102F, and by the time I cycled back to it read 139F. Not sure what that was about, but I followed mrboca's procedures to the letter the following day.



I think that I set the temperature to 72 72... I followed what the STAR TekInfo link said. Anyway, I received the manifold gauge this afternoon. I'm going to watch a few videos on how to use it, but can you tell me what procedure you would want me to do tomorrow morning before the car sees any use?

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Watch the videos regarding the the valve settings and connect it to the high side and low side valves. with the key in position 2, read the sensor values especially item 7, the pressure sensor. Check item 1, indoor temperature sensor. Make sure you set the target temperatures to lower than the indoor temp sensor reading to ensure that the duovalves do not operate. That is why I suggested you set it to LO LO. With the indoor temp of 67 (as it was in your case) 72-72 setting will actually heat your car when the engine is running and warmed up.

After you take the readings from the gauges and sensors, start the car with the a/c on temp settings LO LO, and let the engine run for 4 to 5 minutes. Take readings of sensor and gauges again, making sure that the compressor is running with visual inspection. Observe changes in gauge readings as well as pressure sensor and evap temp sensor (item 5) readings.

Once you post the results, we take it from there.
 

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Discussion Starter #19
Watch the videos regarding the the valve settings and connect it to the high side and low side valves. with the key in position 2, read the sensor values especially item 7, the pressure sensor. Check item 1, indoor temperature sensor. Make sure you set the target temperatures to lower than the indoor temp sensor reading to ensure that the duovalves do not operate. That is why I suggested you set it to LO LO. With the indoor temp of 67 (as it was in your case) 72-72 setting will actually heat your car when the engine is running and warmed up.

After you take the readings from the gauges and sensors, start the car with the a/c on temp settings LO LO, and let the engine run for 4 to 5 minutes. Take readings of sensor and gauges again, making sure that the compressor is running with visual inspection. Observe changes in gauge readings as well as pressure sensor and evap temp sensor (item 5) readings.

Once you post the results, we take it from there.
Not bad for $25.99, I was skeptical about the instructions saying to only finger tighten the knobs and fittings, but no leaks at all and well built.

Anyway with the engine off and ambient temperature at 66F,

LO LO
E/FF
1/66
2/66
3/73
4/73
5/69
6/76
7/04
8/67
9/27
10/6.0
11/2.4
12/4.3
20/3.2
21/32
22/00
23/32
24/11.3
40/164
41/85
42/40
43/136

With engine on for 5 minutes,

LO LO
1/66
2/66
3/71
4/69
5/69
6/145
7/04
8/64
9/30
10/6.0
11/2.4
12/4.2
20/3.2
21/44
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136

1/66
2/66
3/71
4/71
5/69
6/150
7/04
8/64
9/31
10/6.0
11/2.4
12/4.2
20/3.2
21/44
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136

Also took readings after running errands with climate control on EC,

1/87
2/84
3/87
4/87
5/85
6/202
7/06
8/134
9/27
10/6.0
11/1.1
12/4.1
20/3.2
21/42
22/00
23/32
24/13.3
40/164
41/85
42/40
43/136


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1998 E320 base sedan @ 160kmiles
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Thanks for the test results. I am just wondering if you have enough refrigerant in the system. You may have very little in liquid form. I would add a can (12 ounce) of refrigerant (you can get from WM for $4, if you have the piercing adapter) and see what happens to the readings. Make sure you PURGE the air from the manifold hoses by releasing some refrigerant from the charging side prior to charge.
 
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