Intermitten AC - compressor clutch?
Thread Starter
MBWorld Fanatic!
Joined: Jan 2009
Posts: 2,780
Likes: 115
From: Northern NJ
GLK 350 / Porsche 993
Intermitten AC - compressor clutch?
I have 2010 GLK with 123k miles that I have had since new. (GLK forum is less active and C 204 is a bit older so maybe somebody had similar issue here)
I have been having a weird AC issue. When car sits for a while, AC doesn't really work when I start. But if I give some revs (in N to 3-4k rpm) the AC kicks in and blow ice cold. It will usually work after restart just not after sitting for a while.
I'm guessing it has to do with pulley/clutch at the compressor.
Any experiences or fixes besides replacing the entire compressor?
TIA
I have been having a weird AC issue. When car sits for a while, AC doesn't really work when I start. But if I give some revs (in N to 3-4k rpm) the AC kicks in and blow ice cold. It will usually work after restart just not after sitting for a while.
I'm guessing it has to do with pulley/clutch at the compressor.
Any experiences or fixes besides replacing the entire compressor?
TIA
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,376
Likes: 703
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Seen your posts on GLK forum and judge your competency above average, so are you certain it’s the clutch? Neither of my 204s had any AC problems, but my W163 acted just like this. It wasn’t the compressor clutch, it was the pressure limit switch that had gone bad and was sensing a low charge and keeping the compressor off until the engine revs got up to about 3000. I didn’t find it. I assumed the refrigerant charge was low, so I just added a can of 134a. When that didn’t help, brought it to an indie shop who said I had it overcharged and it was the switch that was bad. Less costly than compressor but it still takes a shop to discharge and evacuate the system, then recharge with refrigerant.
Thread Starter
MBWorld Fanatic!
Joined: Jan 2009
Posts: 2,780
Likes: 115
From: Northern NJ
GLK 350 / Porsche 993
Seen your posts on GLK forum and judge your competency above average, so are you certain it’s the clutch? Neither of my 204s had any AC problems, but my W163 acted just like this. It wasn’t the compressor clutch, it was the pressure limit switch that had gone bad and was sensing a low charge and keeping the compressor off until the engine revs got up to about 3000. I didn’t find it. I assumed the refrigerant charge was low, so I just added a can of 134a. When that didn’t help, brought it to an indie shop who said I had it overcharged and it was the switch that was bad. Less costly than compressor but it still takes a shop to discharge and evacuate the system, then recharge with refrigerant.
The pressure limit switch makes makes sense because when I hooked up one of those AC-refill can with a gauge, it said (see manual) so pressure must have been out of whack.
I think I did similar thing with adding more R134 last year so might also have overfilled system.
Joined: Nov 2016
Posts: 7,847
Likes: 3,499
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Had a 2001 Audi A4 with the same problem. If you overcharge the system, the pressure switch will keep it off. So, a bad switch may do the same.
Thread Starter
MBWorld Fanatic!
Joined: Jan 2009
Posts: 2,780
Likes: 115
From: Northern NJ
GLK 350 / Porsche 993
I assume that's what you are referring to.
https://blog.fcpeuro.com/how-to-merc...ressure-switch
Looks like it can be diagnosed with a scan tool, too.
This would be a pretty easy fix.
https://blog.fcpeuro.com/how-to-merc...ressure-switch
Looks like it can be diagnosed with a scan tool, too.
This would be a pretty easy fix.
Thread Starter
MBWorld Fanatic!
Joined: Jan 2009
Posts: 2,780
Likes: 115
From: Northern NJ
GLK 350 / Porsche 993
Did a bit of testing today.
-Started the car with icarsoft hooked up. No cold air and Refrigerant pressure was at 6 bar.
-Revved the engine, pressure went up to 9-10bar and cold air started blowing.
-I added a bit more R134. Pressure was up to 11bar blowing cold.
-If I shut the Ac off pressure goes down to 6bar.
Either, system was simply a bit low due to tiny leak (I doubt it's overfilled because when it works, it works very well)
Or back to my original theory that clutch/compressor is not engaging properly at low RPMs
I doubt it's overfilled because when it works, it works very well.
-Started the car with icarsoft hooked up. No cold air and Refrigerant pressure was at 6 bar.
-Revved the engine, pressure went up to 9-10bar and cold air started blowing.
-I added a bit more R134. Pressure was up to 11bar blowing cold.
-If I shut the Ac off pressure goes down to 6bar.
Either, system was simply a bit low due to tiny leak (I doubt it's overfilled because when it works, it works very well)
Or back to my original theory that clutch/compressor is not engaging properly at low RPMs
I doubt it's overfilled because when it works, it works very well.
Trending Topics
Junior Member
Joined: Jan 2022
Posts: 45
Likes: 5
c250 W204
Originally Posted by NYCGLK;[url=tel:8827793
8827793[/url]]Did a bit of testing today.
-Started the car with icarsoft hooked up. No cold air and Refrigerant pressure was at 6 bar.
-Revved the engine, pressure went up to 9-10bar and cold air started blowing.
-I added a bit more R134. Pressure was up to 11bar blowing cold.
-If I shut the Ac off pressure goes down to 6bar.
Either, system was simply a bit low due to tiny leak (I doubt it's overfilled because when it works, it works very well)
Or back to my original theory that clutch/compressor is not engaging properly at low RPMs
I doubt it's overfilled because when it works, it works very well.
-Started the car with icarsoft hooked up. No cold air and Refrigerant pressure was at 6 bar.
-Revved the engine, pressure went up to 9-10bar and cold air started blowing.
-I added a bit more R134. Pressure was up to 11bar blowing cold.
-If I shut the Ac off pressure goes down to 6bar.
Either, system was simply a bit low due to tiny leak (I doubt it's overfilled because when it works, it works very well)
Or back to my original theory that clutch/compressor is not engaging properly at low RPMs
I doubt it's overfilled because when it works, it works very well.
in my case there was a leak from one of the hoses that had an updated part number. The ac recharge cans seem to never work, have to have professionals use their equipment.
MB World Stories
The Best of Mercedes & AMG
8 Oddball Mercedes Ideas That Actually Made it to Production
Verdad Gallardo
Dubai Tuner Gives the Mercedes G-Class An Entirely New Look
Verdad Gallardo
Six Gift Ideas Your AMG Loving Dad or Grad Will Cherish
7 Craziest Things AMG Gas Ever Built
Verdad Gallardo
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know
Verdad Gallardo
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
