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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #1
I'm in Utah and it's about 92° F outside right now. I like my A/C to be blisteringly cold and my 1998 E300TD just doesn't quite do it.

I've got a recycling machine and I've pulled out refrigerant and put in a good charge (1.0KG if memory serves).

1. Sensors:

1. (Inside Temp): 100
2. (Outside Temp): 114
3. (Left Heater Core Temp): 55
4. (Right Heater Core Temp): 57
5. (Evaporator Temp): 120
6. (Engine Coolant Temp): 188
7. (Refrigerant Pressure): 18
8. (Refrigerant Temp): 120
9. ???: 58
10. Blower Control Voltage: 5.7
11. Emission Sensor: 4.3
12. Sun Sensor: 4.1
20. Control Current for Auxiliary Fan: 16.3
21. Engine Speed: 42
22. Vehicle Speed: 00
23. Terminal 58d: 32
24. Battery Voltage: 12.7
40. Software Status: 164
41. Hardware Status: 85
42. ???: 104
43. ???: 136

2. DTC Error Codes:
B1416 - Coolant circulation pump (M13)
B1235 - Emissions sensor (B31)

Questionable values to me seem like:

5: 120° evap temp seems high
21: 4200 RPM at idle seems silly
23: 32%? I'm not sure what sane values for this should be.

Am I just having unrealistic expectations? It cools things down okay and cools down quite a bit when I get driving. The cooling fans up front seem to engage just fine and really take off at times. A/C gauges look fairly normal but if someone tells me more of what to look for I'd be happy to do that.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
You need to take the sensor readings when the engine coolant temperature is close to ambient with engine not running. This should provide sensor values to compare with the above. 120 for the evap core temp is high, probably a sensor issue. item 21 is a known issue for the E300 and E420/430. No explanations why it is so, as far as I know. Item 23 is the percentage of the display illumination. If you set it to maximum, the value should go up to max (99). Item 24, battery seems a bit low. Typically it shows around 13.3. But maybe because of your aux fans are running at highest speed (item 20).
 

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E250 Bluetec Sprinter250 Bluetec
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37,026 Posts
Those number are senseless unless you tell us when and in what car condition they are taken.
What sensors calibration test show?
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #4
Those number are senseless unless you tell us when and in what car condition they are taken.
What sensors calibration test show?
Sensor values were taken with the car running and up to temperature. Vehicle was stationary at the time. This was 20 minutes ago, so full sunshine, 92F outside.

I'll wait for it to cool and take them again.
 

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E250 Bluetec Sprinter250 Bluetec
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37,026 Posts
You have refrigerant at high pressure, yet evaporator is hot.
That makes no sense, what brings us back to calibration test.
 

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E250 Bluetec Sprinter250 Bluetec
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You also have voltage problem, so fix that before worrying about AC.
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #7
Just took new readings. Car sat overnight, not running:

1. (Inside Temp): 125
2. (Outside Temp): 76
3. (Left Heater Core Temp): 84
4. (Right Heater Core Temp): 82
5. (Evaporator Temp): 134
6. (Engine Coolant Temp): 64
7. (Refrigerant Pressure): 04
8. (Refrigerant Temp): 73
9. 27
10. Blower Control Voltage: 5.7
11. Emission Sensor: 4.5
12. Sun Sensor: 2.2
20. Control Current for Auxiliary Fan: 3.2
21. Engine Speed: 32
22. Vehicle Speed: 00
23. Terminal 58d: 32
24. Battery Voltage: 11.3
40. Software Status: 164
41. Hardware Status: 85
42. ???: 104
43. ???: 136


I took a reading with my multimeter at the jump start terminal in the engine bay. Battery was at 11.9 volts before starting and 12.6 after. Looks like the battery may be going bad. Car still starts fine, but that may change in winter.

Regardless, I do have a 0.6 volt difference between my readings with the multimeter and the climate control. Is that within spec? Where's the battery voltage sensor at?

I have checked battery connections and they're clean and good. I'm going to grab a new battery later today.

Now, back to my original question, sensor 5, evap temp, seems broken. I'm going to take a look at replacing that. Some posts online suggest it's a simple thermistor that I can buy from digikey, etc. so I'll look at doing that. Any other suggestions?
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts

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1998 E320 wagon
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1,142 Posts
Looks like it’s time for an evaporator sensor. Maybe a cabin sensor as well.

How is engine speed 32 with the engine off?

Sixto
98 E320 wagon 197K miles
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
Looks like it’s time for an evaporator sensor. Maybe a cabin sensor as well.

How is engine speed 32 with the engine off?

Sixto
98 E320 wagon 197K miles
This is the nature of these E300/E420/430 cars. Also it has a K2 comm problem, and it is possibly due to miscoding of the version.
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #11
This is the nature of these E300/E420/430 cars. Also it has a K2 comm problem, and it is possibly due to miscoding of the version.
What does the K2 comm problem cause? And what could I do to recode it?

I just ordered the new sensor. Good call, I was thinking they'd be $100+ still. Gonna swing by the parts store to get a charging system test done but I'm fairly confident it's the battery. I pulled this from another car and I had left the lights on a few times with it so I figured it's days were numbered.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
K2 signal line will tell the instrument cluster (from the climate controller) what the refrigerant pressure is, and idle speed increase, when the compressor is engaged.
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #13
Got it. Just got back from the parts store. It's the alternator that's bad. Supposedly the voltage regulator. I replaced it with a Bosche a few years back. I'm debating between doing that again or just getting a new alternator.

Good reminder to always test and validate before throwing parts at it.

As for the K2/459 error, I didn't see that code in the DTC. I'll give it a bit and check again. Maybe that was a different thread?
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
Yeah you are right, it was from some other thread from Brashears. Check the fault codes, and the operation of the aux fan. The fans should turn on when the item 7 pressure goes above 14 to 15 bars and should go max speed above 22 bars, if I remember correctly.
 

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E250 Bluetec Sprinter250 Bluetec
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37,026 Posts
Don't get sidetracked by by forum whining.
Fix your charging system and then do the sensor calibration again.
Yes ECU reading voltage about 0.5 v lower is normal.
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #16
Don't get sidetracked by by forum whining.
Fix your charging system and then do the sensor calibration again.
Yes ECU reading voltage about 0.5 v lower is normal.
I've got a voltage regulator on the way. I'm hoping the $15 fix works. If not it'll be $200 for a rebuilt alternator.

Now I just get to play the waiting game till that and my evap sensor arrive.
 

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E250 Bluetec Sprinter250 Bluetec
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37,026 Posts
$15 sounds like Chinese VR (OE are made in India).
I gave it a try years ago and even it work, it would not activate at idle.
So the light would come unless I would push the gas pedal right after the start. It did work in normal operation, but the light got annoying enough that after few weeks I put Indian stuff
Let us know how yours work?
 

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1982 300SD (340k miles), 1998 E300 Turbo Diesel (331k miles), 1982 300D Turbo (330k miles)
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52 Posts
Discussion Starter #18
I got the evap sensor replaced. Much better results now ranging from 35 to 37 at 86° outside. Waiting to see how it does in the noon day sun now.

I also got the voltage regulator replaced. Replacement is made in Taiwan, so depending on who you ask, it may or may not be Made in China. I'm on the it's probably better than China but may not be best. The old one had quite a bit of corrosion on it and did need to be replaced from what I can tell.

After replacing the voltage regulator it works a bit better. 12.9 on startup up to 13.1 from the climate control.

Unfortunately I think my alternator is at about the end of its usable life. 330k miles have taken its toll. In the last picture if you look at the part where the brush sits (the commutator?), especially the inner one, it's worn very significantly. I think a new alternator is in my future.
 

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E250 Bluetec Sprinter250 Bluetec
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Easy test for alternator is turning all the headlights, rear defroster and blower on high and then read the voltage. Your old VR had good brushes, so it is possible your diodes are burning out.
It is made in Taiwan, but it is Bosch, so hopefully with Bosch QC. What did the box say?
Evaporator temperature at 35F is perfect, but would not hurt to do calibration test on new sensor as well.
 

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1999 E430; 2005 ML500
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1,739 Posts
You can sand down the slip rings to get them smoother, or attack them like this Jawa on Tattooine, but probably false economy vs just replacing.

 
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