Odd A/C issue, anyone seen this?
Thread Starter
Super Member
Joined: Apr 2017
Posts: 518
Likes: 76
From: Mountaintop, PA
'14 W212 Sport, '52 MG TD, '21 Jeep Gladiator Rubicon
Odd A/C issue, anyone seen this?
'14 W212 4Matic gas
I have noticed over the last month or so that my A/C button was of, when I am used to it being on almost all the time. When I would push the button it would blink 3 times and stay off. OK, I figure it's something I hadn't noticed before (it's my wife's car) so I didn't think much about it. We haven't exactly been out of the woods with winter yet, so it's not like the car seemed warm.
Yesterday was the first day we really needed A/C and it wasn't blowing cold. Button still off, 3 blinks and staying off. Uh-oh.
I have an iCarsoft MBII scanner so I got it out when I got home. There are 5 pages of A/C data logging that I went through. Each parameter has a line that ends with YES or NO, essentially meaning "is this the thing keeping my AC from running, yes or no?" First thing in the list was "Is AC Button pushed", and it said no. In fact every parameter on every page said no, i.e. the car thinks the A/C is running fine. Or at least nothing is actively keeping it off. Pressures looked good, I mean at least the system wasn't empty, which was my biggest fear. I don't know if I have it in me to do an evaporator job on this car.
On my scanner, you then have to back out through all the previous pages. I get back to page #1 and now, "Is AC Button pushed" is reading "YES" (I swear on the first loop through the menus it said NO). I push the AC button, and the light comes on and the A/C starts working. Shut the car off, turn it back on, yep still working.
Not that I'm looking a gift horse in the mouth or anything, but has anyone seen this before and is there something I need to watch out for? Or did a bit just get stuck in the climate control module or something?
Perplexed,
Darel
I have noticed over the last month or so that my A/C button was of, when I am used to it being on almost all the time. When I would push the button it would blink 3 times and stay off. OK, I figure it's something I hadn't noticed before (it's my wife's car) so I didn't think much about it. We haven't exactly been out of the woods with winter yet, so it's not like the car seemed warm.
Yesterday was the first day we really needed A/C and it wasn't blowing cold. Button still off, 3 blinks and staying off. Uh-oh.
I have an iCarsoft MBII scanner so I got it out when I got home. There are 5 pages of A/C data logging that I went through. Each parameter has a line that ends with YES or NO, essentially meaning "is this the thing keeping my AC from running, yes or no?" First thing in the list was "Is AC Button pushed", and it said no. In fact every parameter on every page said no, i.e. the car thinks the A/C is running fine. Or at least nothing is actively keeping it off. Pressures looked good, I mean at least the system wasn't empty, which was my biggest fear. I don't know if I have it in me to do an evaporator job on this car.
On my scanner, you then have to back out through all the previous pages. I get back to page #1 and now, "Is AC Button pushed" is reading "YES" (I swear on the first loop through the menus it said NO). I push the AC button, and the light comes on and the A/C starts working. Shut the car off, turn it back on, yep still working.
Not that I'm looking a gift horse in the mouth or anything, but has anyone seen this before and is there something I need to watch out for? Or did a bit just get stuck in the climate control module or something?
Perplexed,
Darel
Thread Starter
Super Member
Joined: Apr 2017
Posts: 518
Likes: 76
From: Mountaintop, PA
'14 W212 Sport, '52 MG TD, '21 Jeep Gladiator Rubicon
Well, the issue came back today. It's reading button not pushed, and also no pressure and low pressure. I am suspicious of the pressure sensor, since I managed to reset it last night and it had pressure and blew cold, and when I put my gauges on it, I have some pressure (not sure what it's supposed to be but the ECU is saying it's 0 and there's not really any such thing as 0 pressure). Poking around to the best of my ability I can't find anything, and it seems like most of the system is buried up against the firewall. Any idea where the pressure sensor is?
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Well, the issue came back today. It's reading button not pushed, and also no pressure and low pressure. I am suspicious of the pressure sensor, since I managed to reset it last night and it had pressure and blew cold, and when I put my gauges on it, I have some pressure (not sure what it's supposed to be but the ECU is saying it's 0 and there's not really any such thing as 0 pressure). Poking around to the best of my ability I can't find anything, and it seems like most of the system is buried up against the firewall. Any idea where the pressure sensor is?
Check that sensor wiring connections don't look oxidized from rain capillarity.
These pressure sensors do go bad...
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,142
Likes: 1,294
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
The pressure sensor is in front in piping under the condenser like CaliBenzDriver says. You access it by removing the front splash panel. Just disconnect/reconnect the harness a few times as it may just have a bad connection due to corrosion in the harness.
Pressure sensors usually do not go bad part of time. They normally die all together, but your system did not work, then worked and now does not work again so for me it kind of tells it is not a bad pressure sensor, it is "flaky" bad connection to it.
