Weird A/C Compressor Behavior
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'97 E200, '06 E350 & '23 E350
Not sure, but computer monitors the voltage as well and quite possible that faulty charging system makes it killing AC.
And yes, minute intervals indicate that it is computer fluctuating the system, not a sensor fault. Confirm that by observing pressure #7. If it fluctuates with the same intervals, you know the sensor is good.
So start with fixing confirmed problem, what is your charging system. Voltage should stay at 13.5V read on cliimatronic, or 13.9V on battery clamps. If not- replace voltage regulator.
And yes, minute intervals indicate that it is computer fluctuating the system, not a sensor fault. Confirm that by observing pressure #7. If it fluctuates with the same intervals, you know the sensor is good.
So start with fixing confirmed problem, what is your charging system. Voltage should stay at 13.5V read on cliimatronic, or 13.9V on battery clamps. If not- replace voltage regulator.
The car is going in for servicing shortly, we'll have an answer then I guess
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'97 E200, '06 E350 & '23 E350
Alternator was replaced and no difference was noted, voltage on Clima unit jumped to 13.4V so that was useful anyway
Mercedes is trying to figure the issue out, I noticed near the right duovalve that a white Vaccuum line (coming from the firewall behind the engine) was spliced into a green vaccuum line (coming from the passenger side firewall) , that isn't right is it? Could it mess with anything?
Mercedes is trying to figure the issue out, I noticed near the right duovalve that a white Vaccuum line (coming from the firewall behind the engine) was spliced into a green vaccuum line (coming from the passenger side firewall) , that isn't right is it? Could it mess with anything?
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From: V E G A S
1922 Ford Model T / no OBD
When you are getting 20 bars of pressure and 2C on the core, your compressor is good.
Something is shutting compressor off and on, so the following test would be enter hot car, display pressure #7, start the engine and observe the pressure for next few minutes of driving. That would indicate when compressor goes to idle and help in finding what might cost it.
Something is shutting compressor off and on, so the following test would be enter hot car, display pressure #7, start the engine and observe the pressure for next few minutes of driving. That would indicate when compressor goes to idle and help in finding what might cost it.
Last edited by kajtek1; Sep 25, 2019 at 10:41 AM.
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'97 E200, '06 E350 & '23 E350
The dealership went through a lot of test to determine this, they told me the compressor is unable to hold pressure for extended length, I figured it could be a bad pressure sensor but since the Compressor rattles anyway I didn't really mind replacing it. However one thing that complemented their findings was that even when #7 was showing 20 bars (when aux fan was in maintenance mode at full blast), the behavior did not change and the core temperature would fluctuate.
Wild goose chase I guess
Wild goose chase I guess
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From: V E G A S
1922 Ford Model T / no OBD
It's only wild goose chase if you don't know what you are doing.
Having system where 7 or more sensor regulate the output, it takes a process of elimination to find the intermittent failure.
The temperature can change due to different air flow, opening heating valve and probably several more parameters.
Let us know final outcome?
Having system where 7 or more sensor regulate the output, it takes a process of elimination to find the intermittent failure.
The temperature can change due to different air flow, opening heating valve and probably several more parameters.
Let us know final outcome?
Thread Starter
Member
Joined: Oct 2011
Posts: 211
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'97 E200, '06 E350 & '23 E350
It's only wild goose chase if you don't know what you are doing.
Having system where 7 or more sensor regulate the output, it takes a process of elimination to find the intermittent failure.
The temperature can change due to different air flow, opening heating valve and probably several more parameters.
Let us know final outcome?
Having system where 7 or more sensor regulate the output, it takes a process of elimination to find the intermittent failure.
The temperature can change due to different air flow, opening heating valve and probably several more parameters.
Let us know final outcome?
In any case, I will surely keep you posted!
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From: V E G A S
1922 Ford Model T / no OBD
This is variable output compressor, so pressure fluctuation is how it works.
Maintenance mode on fan would fluctuate speed as well, while for testing you want it to set to MAX.
Anyway, good you are 1 in million who trust his dealer
Maintenance mode on fan would fluctuate speed as well, while for testing you want it to set to MAX.
Anyway, good you are 1 in million who trust his dealer
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Thread Starter
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'97 E200, '06 E350 & '23 E350
And I understand why some dealers have a bad reputation but where I live you really don't want to mess with independent mechanics, they're badly equipped, don't have access to WIS or EPC, turns into a mess quickly.
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'97 E200, '06 E350 & '23 E350
Just a final update: AC Compressor, dryer, line from dryer to condenser replaced and system refilled and pressure tested = AC blows ice cold now within seconds of startup. Rattle is now gone from the engine compartment when AC is on as well.. Issue is fully resolved!
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'97 E200, '06 E350 & '23 E350
Thread Starter
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Joined: Oct 2011
Posts: 211
Likes: 10
'97 E200, '06 E350 & '23 E350
Some new updates that are A/C related but not to the previous issue.
Good News first: A/C is freezing, cools the car very fast and heat is also exceptional. Good to have it back.
Neutral News: Was checking some codes on the A/C unit and everything was clear except one code: B1421 -> Pulse Unit (N65) that controls the Engine fan (I have only one suction fan not 2 AUX). However the fan does respond to the "test" mode and goes into full blast if I hold both Auto buttons long enough -> shows 10 mA. I don't see the fan running at any point during driving (always at 0.0V) but yet again engine temperature is always at 87C. Might get the N65 module and replace it just as a preventive maintenance measure. Opinions?
Bad News: Driver side sometimes blows cool air while the passenger side is ice cold. When that happens, sensor #3 reads 45 C, #4 reads 08 C and #5 is mostly constant at 4C fluctuating between 2 and 6 C which is the operating range on WIS so no issues here. All three sensors report exactly the same value on a cold morning so sensors are accurate. Duo-Valve was replaced 2 months ago because it was blowing hot air on driver side and it was solved, this is not hot air but cool (not freezing) air. Could that be normal operation? At no point is the cabin hot, it's actually ice cold even with the big offset between #3 & #4 overall. If not should I go ahead and do the flap test?
Thanks!
Good News first: A/C is freezing, cools the car very fast and heat is also exceptional. Good to have it back.
Neutral News: Was checking some codes on the A/C unit and everything was clear except one code: B1421 -> Pulse Unit (N65) that controls the Engine fan (I have only one suction fan not 2 AUX). However the fan does respond to the "test" mode and goes into full blast if I hold both Auto buttons long enough -> shows 10 mA. I don't see the fan running at any point during driving (always at 0.0V) but yet again engine temperature is always at 87C. Might get the N65 module and replace it just as a preventive maintenance measure. Opinions?
Bad News: Driver side sometimes blows cool air while the passenger side is ice cold. When that happens, sensor #3 reads 45 C, #4 reads 08 C and #5 is mostly constant at 4C fluctuating between 2 and 6 C which is the operating range on WIS so no issues here. All three sensors report exactly the same value on a cold morning so sensors are accurate. Duo-Valve was replaced 2 months ago because it was blowing hot air on driver side and it was solved, this is not hot air but cool (not freezing) air. Could that be normal operation? At no point is the cabin hot, it's actually ice cold even with the big offset between #3 & #4 overall. If not should I go ahead and do the flap test?
Thanks!
Thread Starter
Member
Joined: Oct 2011
Posts: 211
Likes: 10
'97 E200, '06 E350 & '23 E350
Some new updates that are A/C related but not to the previous issue.
Good News first: A/C is freezing, cools the car very fast and heat is also exceptional. Good to have it back.
Neutral News: Was checking some codes on the A/C unit and everything was clear except one code: B1421 -> Pulse Unit (N65) that controls the Engine fan (I have only one suction fan not 2 AUX). However the fan does respond to the "test" mode and goes into full blast if I hold both Auto buttons long enough -> shows 10 mA. I don't see the fan running at any point during driving (always at 0.0V) but yet again engine temperature is always at 87C. Might get the N65 module and replace it just as a preventive maintenance measure. Opinions?
Bad News: Driver side sometimes blows cool air while the passenger side is ice cold. When that happens, sensor #3 reads 45 C, #4 reads 08 C and #5 is mostly constant at 4C fluctuating between 2 and 6 C which is the operating range on WIS so no issues here. All three sensors report exactly the same value on a cold morning so sensors are accurate. Duo-Valve was replaced 2 months ago because it was blowing hot air on driver side and it was solved, this is not hot air but cool (not freezing) air. Could that be normal operation? At no point is the cabin hot, it's actually ice cold even with the big offset between #3 & #4 overall. If not should I go ahead and do the flap test?
Thanks!
Good News first: A/C is freezing, cools the car very fast and heat is also exceptional. Good to have it back.
Neutral News: Was checking some codes on the A/C unit and everything was clear except one code: B1421 -> Pulse Unit (N65) that controls the Engine fan (I have only one suction fan not 2 AUX). However the fan does respond to the "test" mode and goes into full blast if I hold both Auto buttons long enough -> shows 10 mA. I don't see the fan running at any point during driving (always at 0.0V) but yet again engine temperature is always at 87C. Might get the N65 module and replace it just as a preventive maintenance measure. Opinions?
Bad News: Driver side sometimes blows cool air while the passenger side is ice cold. When that happens, sensor #3 reads 45 C, #4 reads 08 C and #5 is mostly constant at 4C fluctuating between 2 and 6 C which is the operating range on WIS so no issues here. All three sensors report exactly the same value on a cold morning so sensors are accurate. Duo-Valve was replaced 2 months ago because it was blowing hot air on driver side and it was solved, this is not hot air but cool (not freezing) air. Could that be normal operation? At no point is the cabin hot, it's actually ice cold even with the big offset between #3 & #4 overall. If not should I go ahead and do the flap test?
Thanks!
Temperature on driver side shot up to 62C, set both temps to LO bypassing the Duo-Valve... And it fixed it. So I guess warranty claim on the Duo Valve is in order then!
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From: V E G A S
1922 Ford Model T / no OBD
What warranty? You spend $1.3k on AC components replacement and now it is turning you might have bad duovalve?
Would suck to conclude that you were milked $1.3K on replacing good working parts. That is why I always advise at least DIY troubleshooting.
Did I mention it takes 90 seconds to do it?
Would suck to conclude that you were milked $1.3K on replacing good working parts. That is why I always advise at least DIY troubleshooting.
Did I mention it takes 90 seconds to do it?
Thread Starter
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Joined: Oct 2011
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'97 E200, '06 E350 & '23 E350
This is a different issue that has to do with A Duo Valve that I replaced two months ago because I was having hot air on the left side. The issue seemed solved back then but it looks like the part went bad. The Duo Valve is a Genuine part and thus comes naturally with a warranty. A defective unit will thus be replaced free of charge and the issue solved.
I did my DIY before going to the dealership for the Duo Valve, I ordered the part and gave them the ASRA Work order as well. The dealership is basically 99% used to install parts I had already diagnosed and bought.
But at the end of the day I'm no mechanic, I try what I can, I ask on forums, I read EPC & WIS as much as possible.
I don't get why it seems outrageous to go to a dealership and pay to get quality parts and work done there. I do buy OEM when the price gap is huge (200$ per side for hood struts is outrageous when the OEM is 30$).
I'm posting here because I believe car repairs require multiple opinions and I have great respect for every community member here, there is no point in trying to rub something in my face that's not even relevant.
