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Absolutely no cool. Compressor is engaged. Correct amount R134. Compressor replaced.
Dear forum members!
I can't figure out what's wrong!
Summary: Compressor is engaged. Correct amount R134. Compressor replaced. No DTC error codes. Absolutely no cooling.
w210 E240 -00, 16500 km (10300 miles)
Last summer:
No cool air what so ever.
Filled AC at indie with equipment. Filled by weight (according to his tables).
Clutch is engaging.
No pressure build up according to indies gauges. No temp differences anywhere (felt on hoses and looked through thermal camera). No cool on any sensor (system read out)
He couldn't help me more. I couldn't found anything relevant by googling.
During winter:
The most plausible cause I could think of was that compressor is totally gone. Totally wide open expansion valve was my other explanation but I found that less plausible.
System pressure slowly falling and after a couple of month there was no gas left
This week:
Took a chance and ordered a used compressor.
Indie replaced the old one and dryer and filled it up again.
He should measure pump pressure but clutch disengaged immediately.
I picked the car up this evening and when I got home the clutch was working.
Numbers looks very similar to those last summer.
06 = 68°C (154F) coolant temp, have also tried with fully hot engine.
07 = 04 refrig. pressure in bar. Don't matter if engine is running or not.
08 = 19°C (66F) refrig temp sensor
No DTC error codes.
Have tested both idling and 2000 RPM. No noticeable change in any number (aside from engine coolant).
No temp differences on hoses. Can't find any low temp anywhere with thermal camera.
EDIT: Compressor is consuming at least some power. There is an engine rpm change when compressor engage and disengage. Climatronic dual zone with rest button.
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Last edited by lennart258; 06-03-2017 at 12:53 PM.
If the expansion valve was open, but the compressor was working, the outlet of the compressor would still be warm and the inlet cool, not like a good working system but there would be some difference.
If the system is losing refrigerant, you need to fix the leaks first. Then have it vacuumed and charged and see what works and what doesn't.
Does the car have any cooling system faults or codes stored in the M/E? There's a whole list of things that can disable the a/c system.
If the expansion valve was open, but the compressor was working, the outlet of the compressor would still be warm and the inlet cool, not like a good working system but there would be some difference.
If the system is losing refrigerant, you need to fix the leaks first. Then have it vacuumed and charged and see what works and what doesn't.
Does the car have any cooling system faults or codes stored in the M/E? There's a whole list of things that can disable the a/c system.
I was assuming that, if the compressor is so totally damage, that no pumping action can be noticed, it's reasonable to think that the compressor itself is leaking. There was (maybe is still) a small leakage but the main question here is why compressor don't pump refrigerant when there is refrigerant in the system. The probability that both compressors are fully broken seems very low. However, the probability is of course bigger then zero.
Having less than 1/2 of proper troubleshooting, I still have to go to crystal ball for the rest, but looks to me you are low on refrigerant.
Do proper troubleshooting per MBMedic site and we will know for sure
You want to run AC at 70f ???
What temperature you set on the controls?
Having less than 1/2 of proper troubleshooting, I still have to go to crystal ball for the rest, but looks to me you are low on refrigerant.
Do proper troubleshooting per MBMedic site and we will know for sure
You want to run AC at 70f ???
What temperature you set on the controls?
Temp controls are set to "Lo" on both sides. Refrigerant looks a little bit low but low side pressure readings indicated by MBmedic at 70°F ambient temperature are in this region. Still, the compressor is running but don't pump.
MBmedic talking about liquid lock in compressor. I going to try finding more information about that.
70F don't require ac. I happy that it wasn't warmer when I did the test and diagnose on a non working ac system.
http://www.mercedesmedic.com/ac-air-...le-codes-list/
Sorry, I did not know MBMedic has 2 AC help sites.
Read the comments at the bottom.
When setting temp to LO should force compressor to max output, this is not natural circumstance and dealing with 8 or more sensors affecting the system you might trigger something else.
Do compressor test on hot afternoon and that will leave no questions.
http://www.mercedesmedic.com/ac-air-...le-codes-list/
Sorry, I did not know MBMedic has 2 AC help sites.
Read the comments at the bottom.
When setting temp to LO should force compressor to max output, this is not natural circumstance and dealing with 8 or more sensors affecting the system you might trigger something else.
Do compressor test on hot afternoon and that will leave no questions.
Today was a hot day! Temp set to 14°C (lowest before "LO") and I got the folwing read outs:
I have never before noticed any AC function in this car. In this test at least right side worked. A couple of hours later when driving home from work there were no AC function again. Sensor values about the same as in my first post in this thread.
And again. 1/2 of data needed for troubleshooting.
Next time you get into hot car, start with displaying pressure #7, than start the engine and observe pressure change for couple of minutes when driving.
Before start the pressure at #7 is 07. Besides yesterday, when some function was observed, the pressure seems unaffected of engine speed and remains at 07.
New readings:
Ignition, idle and 2100 rpm tested. No thermometer at hand but I would say that the temp difference between right and left side air felt much more than 03 and 04 indicates. Refrigerant pressure rose to 18 shortly after start but dropped down to ca 10 after 30 s. Couldn't notice any correlation between engine speed an pressure.
Last edited by lennart258; 07-04-2018 at 05:50 AM.
Did the pressure jump when you start the engine?
Your chart is confusing with double, different numbers at each time.
Looks like your compressor is not engaging. and you can ignore sun sensor error.
Your car voltage looks low both on battery and when charging. Not sure if that is what could affect your AC, but you should fix that regardless.
Recheck the battery and charging voltage with meter on battery clamps.
You have been wasting your time for 11months---wake up your compressor is bad and cant make a constant 15-17 bar---get a real new one not one that is used and new to the car or move to a colder climate.
Did the pressure jump when you start the engine?
Your chart is confusing with double, different numbers at each time.
Looks like your compressor is not engaging. and you can ignore sun sensor error.
Your car voltage looks low both on battery and when charging. Not sure if that is what could affect your AC, but you should fix that regardless.
Recheck the battery and charging voltage with meter on battery clamps.
Sorry for confusing numbers. The fat numbers is the actual numbers from climate control (CC). I added a column with temperatures converted to Fahrenheit to make it easier to read for those who are more familiar with that temperature unit. When checking numbers this time I didn't visually check clutch engagement but almost every time I have looked I can see the clutch engage (besides hearing and also notice RPM changes). Only time I have seen pressure changes (and felt any cold air) are the the two last test after hours on hot parking lot.
I didn't took notice of the low voltage numbers! Just measured it. According too CC the numbers was about the same as last time while DMM measured 12.2 and 14.0 (idle). I would say 14 is ok? Measured between chassi and + socket next to fuse box. Can there be a safety feature in CC that saves current when battery is low? Are there any big current consumers around the cooling system? I don't know of bigger current consumers than the fan and that works fine. I measured change in voltage with fan turned off and with full fan. Voltage drop was about the same from CC and DMM so I wouldn't say there are not any bad power connections to CC.
I'm happy to live in a pretty cold climate. It's not often that I can do tests at high temperatures (34°C (93°F)) as advised by kajtek1. Maybe my compressor isn't perfect but that doesn't seems to be the problem. The only thing I can think of is that there is a expansion valve that get stuck totally open causing compressor just transporting gases without any pressure build up. That doesn't look plausible either. There should be at least some noticeable pressure build up even with valve stuck open!? Is the expansion valve electronically or thermodynamically controlled? At one of the latest test there were some cold on left side but non at right side. Are there two expansion valves or is cold distributed by coolant? Maybe the unbalance is due to a fail solenoid valve but still the main problem is that most of the time there is NO pressure build up while compressor is spinning?
For compressor or valve testing you need to measure low side pressure as well and make sure the compressor is turning.
I still would keep an eye on voltage.
And again, observe compressor pressure when restarting hot car. That can tell a lot in just seconds.
06-02-2017, 06:10 PM
