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1997 W202 C280
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17 Posts
Discussion Starter #1
The AC in my C280 does not work. When i turn it on I don't hear anything turn on or engage. When i put on defrost i hear a blend door actuating but nothing else. I'm at a loss and I believe that I checked all the fuses.

(My front door locks, and sunroof are slow to work, and my back doors dont even lock. I'm not sure if they're related this but maybe it is? this is my first mercedes)
 

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1995 C280 1997 S320
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247 Posts
Hi M Davis.
There could be 2 issues, ac compressor doesn't work or hvac deflector dont operate properly .
First, check if your ac compressor clutch engages when you turn on the ac.
Second, doors not closing might be a concern, you see hvac system and door close/open function in these cars works on vacuum, genersted in part by engine intake cacuum and by a PSE vacuum pump.
Do you hear constanr cycling zooming noise 1-2 sec long every 5 sec? If you do that indicates you have a cacuum leak in the system, if you dont this means either you PSE pump burned out or the fuse is blown.
So arm yourself with a vacuum schematic and a hand vacuum pump from Harbour Freight. It will take some time and effort to find the problem.
 

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1997 W202 C280
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17 Posts
Discussion Starter #4
I'll check the AC compressor and clutch when i can

Whenever i would lock and unlock the car i believe i could hear the vacuum pump from the gas cap area and then from the front passenger side door i would hear a hissing noise for 5 seconds while the door locked and unlocked. the drivers door made a noise but it wasn't as loud as the passenger's door and it didn't make the noise for long. the back doors wont lock or unlock at all and i cant push them down either.

I may have to record what the door locks are doing and post it here
 

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1995 C280 1997 S320
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247 Posts
If you hear PSE pump that's a good sign. Hissing sound coming from the doors when you close or open are the leaking air actuators, usually the plastic cracks and air chamber starts lecking air , those are easy to fix, i used some strachable seal tape from plumbing home depot department. The hard part is to get it out.
 

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W163 and General Mercedes Host
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3,282 Posts
The AC in my C280 does not work. When i turn it on I don't hear anything turn on or engage. When i put on defrost i hear a blend door actuating but nothing else. I'm at a loss and I believe that I checked all the fuses.

(My front door locks, and sunroof are slow to work, and my back doors dont even lock. I'm not sure if they're related this but maybe it is? this is my first mercedes)
Check the voltage of your battery at the terminals. Fully charged battery - around 12.6 volts or above.
When the engine is running - somewhere between 13.7 and 14.7 volts.
 

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Registered
1997 W202 C280
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17 Posts
Discussion Starter #7
We had to replace the battery recently because the one before had a dead cell in the battery.

Would i have to let the car run long enough to let the systems in the car get back to normal?
 

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Registered
1997 W202 C280
Joined
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17 Posts
Discussion Starter #8
If you hear PSE pump that's a good sign. Hissing sound coming from the doors when you close or open are the leaking air actuators, usually the plastic cracks and air chamber starts lecking air , those are easy to fix, i used some strachable seal tape from plumbing home depot department. The hard part is to get it out.
would that also explain why the back doors dont lock and unlock? In that case i'll look into it.
 

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W163 and General Mercedes Host
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3,282 Posts
We had to replace the battery recently because the one before had a dead cell in the battery.

Would i have to let the car run long enough to let the systems in the car get back to normal?
No

[QUOTE="M_Davis, post: 18023827, member: 1245234"

(My front door locks, and sunroof are slow to work, and my back doors dont even lock. I'm not sure if they're related this but maybe it is? this is my first mercedes)
[/QUOTE]
Please discuss this topic/issue on another new thread separate from your AC issue;
And then explain what you mean by your phrase, "slow to work".
Try spraying in some lubrication. For the sunroof, do the same.
 

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1994 W202 C200, 2017 W213 E350e, 1993 W140 S320
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23 Posts
By you don't hear anything do you mean your blower motor is not turning on? if so the case could be a broken blower motor or power issue to the blower motor. If the blower motor works but you don't get cold air then id look into to see if the compressor is running or not.
 

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1997 W202 C280
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17 Posts
Discussion Starter #13
By you don't hear anything do you mean your blower motor is not turning on? if so the case could be a broken blower motor or power issue to the blower motor. If the blower motor works but you don't get cold air then id look into to see if the compressor is running or not.
When i turn on the car, and turn the AC on i don't hear the compressor or blower motor turn on.
 

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W163 and General Mercedes Host
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When i turn on the car, and turn the AC on i don't hear the compressor or blower motor turn on.
READ here
 
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