Has anyone seen this before? It says "Communication with the air conditioner has a malfunction"

Ive searched every forum and can't find an explanation. Please help me turn my AC back on!

 

From what I could find, it appears to be related to your A/C Evaporator Temperature Sensor. Could be a sensor, bad ground, faulty connection, or worst case scenario your PCM is not communicating properly. If you provide your VIN i might be able to look up the sensor part number.

 

Hi Ferguson, you've given some interesting information.

My VIN is WDDHF5GB5BA389257

Here is the history: I recently bought the car, 3 days later the AC stopped working. Pressures showed me the pump was not engaging. Its electric and has a pulley on it but no clutch, you can only tell if its engaged by changes in pressure. A technician with a Snap-On Apollo D8 scanner showed code B1112-15 "Right footwell vent, temperate sensor malfunction."

I pulled the footwell panel and saw the sensor was unplugged, so I plugged it back in and the system started working again. It seems like somebody removed the panel to service a bulb or something, and failed to reconnect the sensor. There is a sensor in the panel vent, and another above it in the evaporator compartment. I removed both sensors and tested them with hot and cold water, resistance values changed dramatically so I put them back. After about 2 weeks, the AC suddenly shut off again. The pump does not engage, while everything else works.

My new Harbor Freight scan tool (Zurich Z11s) works great but displayed a code I can not find anywhere on the internet, including forums and YouTube. My assumption is that if I go back to pay a technician with a Snap-On, I might get a code with a better explanation? There are no codes in the Mercedes enhanced system without a letter like B, P or U. This 1437 is strange.

I pulled a fuse for the AC while the system was on, and got code C164: "No CAN message was received from control unit N22 (AAC [KLA] Control & Operating Unit)".
So in this case, the C designator tells me my scanner does display correct codes unique to Mercedes, and this is why I'm so puzzled by code 1437. Can you tell me how you understood this code might be related to the Evap Temp sensor? If you have access to a list that includes my code, I would love to see it.

This car is extremely clean with only 85k miles on it. I would be shocked if there were any corrosion issues, since I can't see any and the grounds & battery cables are all clean. There are zero other issues with the vehicle.

Thanks for the help! I will retest the Evap sensor.

 

I've attached the schematic and parts list where the A/C Evap Temp Sensor is located. In case it doesn't upload properly, the part number is 220 830 07 72

Honestly, I just googled "Mercedes trouble code 1437 a/c" and it was the second link. https://www.engine-codes.com/p1437.html
Not really sure how or why that code comes up with no lettering, that is peculiar. Though it must be correct, considering it's in the same location as the original code B1112-15 right footwell. However I can't find anything on that B code related to A/C. Strange.
I would hesitate to bring it in for diagnosis multiple times - I'm sure they charge a diag fee every time, even if the resulting find is the same as before. Unless of course you've got great communication with your technician/shop, whoever it may be.

If both sensors appear to be working correctly, then honestly I'm not entirely sure what's going on. I pray it's not your PCM. Although they (for some reason) tend to be cheaper on Mercedes vehicles than other brands, it'll still put you in the hole anywhere between $250 - $500 for the part and $175 - $525 to program it. Furthermore, if it is the PCM, the part can only be ordered from a Mercedes dealer, and they will inform you that it is considered a TRP (Theft-Related Part) and those can't be sold over the counter. The PCM must be installed by the selling dealer. The only loophole to that is if you bring your vehicle to a shop that does business with their local Benz dealer and have the state certifications to buy, install, and program TRP parts.

On the more positive side, you can rule out the sensors (assuming your tests are accurate) and possibly start tracing wires to check for any bad grounds and/or exposed or damaged wires. I would also check all the wiring for the compressor -- I would imagine a different code would be thrown if the compressor is bad but then again it is a 2011 car, so I won't pretend to know.

If there's any more diagrams or schematics that you think might help you, let me know. I doubt I'm supposed to share this kind of information but I like to help people. I'm sorry I don't know more about this subject!

 

Thanks for the info, I replaced both footwell sensors but this time nothing changed. After I reset the codes a different one popped up:C164: No CAN message was received from control unit N22 (AAC [KLA] control & operating unit)
I'll be working on figuring this one out next. Im usually pretty good at repairing AC issues but these cars can be complicated to diagnose. After finding out the first time that the footwell sensor was simply unplugged, Im kind of hoping this is a similar issue... except I'll probably have to take a lot more apart to trace the wiring.

 

Providing a link I hope helps - this is totally out of my area of expertise. I hate tracing wiring
https://www.obd-codes.com/u0164

 

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