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Discussion Starter · #1 ·
I purchased a 1999 300td and the ac is not working properly. I have a full set of manifold gauges and a vacuum pump.

When you first start the car the compressor kicks on. I can turn the ac off and on and the compressor follows. However after 2-3 min the compressor shuts off and will not turn back on unless I restart the car and remove the key. While the compressor is on the passenger side feel cooler but definitely not like it should and the passenger side is ambient temperature.

With the engine running and compressor on the low side is around 30 psi and the high side is around 225 psi.

Below are the ac values with the compressor on.
  1. 81
  2. 123
  3. 150
  4. 144
  5. 143
  6. 216
  7. 15
  8. 133
Any help would be awesome. Thanks
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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Insufficient freon. Add a small can of 134a -- straight 134a, not one of those with "sealant" or "oil" or whatever they sell at the parts store. Straight 134a only.
 

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1999 E430; 2005 ML500
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2,267 Posts
That doesn’t explain the compressor shutoff.
Have you had the gages on to monitor pressure while this happens, and does it happen even if requested temps are “lo”?
 

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Discussion Starter · #4 ·
Yes when the compressor shuts off the high and low pressure gauge try to equalize just like they do when the engine is shut off. Doing some research is it possible the evaporate temp sensor is bad with a reading of 143 value 5?
 

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W210 Section Moderator
1998 E320 base sedan @ 215k miles
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8,952 Posts
I purchased a 1999 300td and the ac is not working properly. I have a full set of manifold gauges and a vacuum pump.

When you first start the car the compressor kicks on. I can turn the ac off and on and the compressor follows. However after 2-3 min the compressor shuts off and will not turn back on unless I restart the car and remove the key. While the compressor is on the passenger side feel cooler but definitely not like it should and the passenger side is ambient temperature.

With the engine running and compressor on the low side is around 30 psi and the high side is around 225 psi.

Below are the ac values with the compressor on.
  1. 81
  2. 123
  3. 150
  4. 144
  5. 143
  6. 216
  7. 15
  8. 133
Any help would be awesome. Thanks
The values you posted does not make much sense. The "in the car" temperature is 81 degrees F while the heater cores are 150 and 144. The evap core temperature is at 143 much higher than the in the car temp, and even the refrigerant temp (133) :). The refrigerant pressure seems fine and the gauges look fine too.

What was the ambient (outside) temperature when you did the test ? I see that you live in north FL, so it was about 90 ?


What you should do is leave the car overnight to let all the fluids to cool down to ambient temperature. Then, in the morning, turn the key to position 2 (without starting the car) and obtain all sensor values (not just 8, 1 to 43) and post them here. This will provide all temp sensors reading which should be in the same range. Then start the engine with the a/c set to LO LO and turned ON, and take the readings again in 5 minutes of engine running, and post them here.

Your coolant temperature is way too high (above water boiling point) which is very high for a diesel.

Also obtain fault codes from the climate controller diagnostic menu.

Stuart from item 3.
 

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Discussion Starter · #6 ·
So the car has been sitting since last night and I pulled the values 1-43 before it was started and for as long as the compressor would run before it shut off.
Yes I do live in Florida and I believe it was around 85 last nigh when I pulled those values. Everything in red are values that were different

Key in Position 2 Cold Engine (OFF)
1. 102
2. 84
3. 105
4. 105
5. 150
6. 83
7. 08

8. 84
9. 21
10. 6.0
11. 1.2
12. 4.1
20. 3.2
21. 32
22. 00
23. 32
24. 11.6
40. 164
41. 32
42. 72
43. 136

Key in Position 2 Engine (ON) AC LOW/LOW
1. 94
2. 84
3. 96
4. 85
5. 150
6. 136
7. 15
8. 116

9. 21
10. 6.0
11. 1.2
12. 4.1
20. 3.2
21. 42
22. 00
23. 32
24. 12.7
40. 164
41. 32
42. 72
43. 136
 

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W210 Section Moderator
1998 E320 base sedan @ 215k miles
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8,952 Posts
You definitely need to replace the evap core temp sensor which s stuck at 150. This should solve your problem. If not, report back.

The refrigerant pressure before the engine starts is a bit high. Given the refrigerant temperature it should be around 6 bars (compared to 8). Have you tried to add refrigerant to solve the cooling problem?

Also post the diagnostic display results. Check if there is any fault code.
 
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