bbearden

The wife and I are about to drive 3000 miles across the country and the A/C in my CLK just stop cooling entirely. I ran a diagnostic test from http://www.eclassbenz.com/acdiag

and I received the following information:
EC light not stuck on
A/C Sensor Values:
Sensor 1: Inside temperature: 77
Sensor 2: OUtside temperature: 127 (This threw a red flag to me because it was around 70 degrees or so but the temp on my gauges showed correctly)
Sensor 3: Left Heater Core temp: 66
Sensor 4: Right Heater Core Temp: 72
Sensor 5: Evaporator Temp: 88
Sensor 6: Engine Coolant Temp: 198
Sensor 7: Refrigerant Pressure: 10
Sensor 8: Refrigerant Temp: 106

There were no error codes when I ran the check for computer codes during the self-check mode. Codes normally start with a "B" followed with numbers but the only thing that popped up for me was "FF" which I do not believe is an error code.

Any ideas here? I am out of warranty on the CLK so I don't want to pay an arm and a leg. Anybody have these same issues?

Thanks in advance!

gregory13lil

I just had the same issue this past weekend but I did not know how to do the disgnostics so I need to learn that part.

But I ended up taking the CLK to the dealership and they said that it was my EC switch that was on. I told them that I had hit it and the light was not on BUT all they said was "Well the Air is cold now and there are no other problems". The good thing about all this is that they did not charge me at all and even gave me a free loaner throughout the weekend and I am out of warranty as well.

Good Luck with this man!!

Greg

bbearden

I'll definitely try that but I am pretty sure I hit my EC switch during the self-dianostic mode this morning. I wish it were as simple as an LED out in the unit. Thanks and glad to hear you got off easy at the dealership. Thats a rarity! Go to the website above that I mentioned if you need to dianose your AC system again. Its very simple and can help with DIY if a sensor or small part has failed.

gregory13lil

Damn thats a sweet site!! Thanks man!!

Greg

bbearden

No problem bro. Yeah the guy did quite a bit of work to put that diagnostic tool together.

So I went out and tried the A/C again with and tried hitting the EC switch but the LED does light up and there is no marked difference in cooling. I haven't located the fuze for the system. Any idea where it is located? The switches and fans all seem to work so I am beginning to think it is a sensor failure that may not have showed in the diagnostics. I didn't get any error codes and no one seems to know what the error code "FF" means.

bbearden

I tried the sensor bypass (refrig. temp and pressure) to see if I could get a response from the system, but still nothing but hot air. From what I can tell I do have engagement of the A/C clutch with the compressor and my refrig. pressure is normal at 10 atm. ,but refrig temperature seems low since it is below that of ambient air temp. (127 vs. 106). To me that means the A/C system cannot pull the heat out of the air in the vehicle. I'm no HVAC technician, but I feel this system was overengineered compared to most cars I'm familiar with.

MarcusF

If I simply turn on my car, let it idle, bring up the diagnostics from rest button, and turn on the AC - all the while never touching the gas pedal - the barometric pressure reading for the Freon in my car is 15/16. This is while the car is idling at 600 RPM - not fast idle from a cold start.

If I saw 10, I'd take that to mean I was low on freon.

bbearden

Marcus, that sounds about right. The number you are seeing is in BAR so it sounds like you are running the right pressure in your system. Thats what my car was seeing after the dealer checked it.

Hitman0187

I ran these tests and got the below ( it says 92 degrees on the dash )

The diag tool says listen for a leak, i have +6 pressure to your system. did the dealer add freon for you ? I fooled with the number and used all the same values except for the pressure which i put a 75 in place of the 16 and then its says its way to low. What number should the pressure be at?

Sensor 1: Inside temperature: 110
Sensor 2: OUtside temperature: 141 (This also threw a red flag to me because it was around 90 degrees or so but the temp on my gauges showed correctly)
Sensor 3: Left Heater Core temp: 59
Sensor 4: Right Heater Core Temp: 59
Sensor 5: Evaporator Temp: 57
Sensor 6: Engine Coolant Temp: 198
Sensor 7: Refrigerant Pressure: 16
Sensor 8: Refrigerant Temp: 132

MilitaryBenz

i would just recharge the system i recently just had this same problem and all it needed was a recharge you will run into the code ff but for some reason its associated with low freon...if you hear some hissing noise or like loud blowing rattling hard to explain but its the actual gas tryin to expand in the compressor but will fail and stop workin if it reaches a really low level recharge first and then run some more diagnositics because then youll be able to check for leaks etc.

Zoom On

Thats funny I just wrote a question about the temp sensor reading dash vs TSR climate control. I was driving around and dash said 70 (correct) but my TSR CC was saying as high as 130 at stop due to engine heat. Once I started moving it dropped right back to 70. As I rolled and the temp went up or down then the dash moved with it. My guess is to keep the engine heat out of the mix it has a speed tie in that says if the car is stopped ignore the reading until moving. Anyone else watched that and see the same?

wnycec

I had my car in the garage all winter and basically summer turning it on every week to keep the engine active. The other day I was fiddling with the cars instrument panel to make sure everything works and I noticed that not only does the air not blow cold but it only blows at one speed (HIGH) although I press the button to decrease the air speed. Does anyone have any experience with this? Any diagnosis or solutions? Thanks in advance!

Hitman0187

I checked out your scenerio and got similar results, in fact it led to another "discovery" - because i have a cabriolet there is some additional things to consider. It was so hot outside and in the car i turned on the a/c looked at the diag numbers and then put the top down to cool off, the cabin temp sensor went to 261 degrees and the air got colder from the vents. i put the top back up and the number immediately switched to 92 degree matching the dash read out.
i think in my case its so damn hot out it takes forever and a day to cool off the air. the lines are sweating under the hood so i guess its fine.

Zoom On

Yeah with the top down it will read 261 for some reason but mine reads the same.

Hitman0187

It goes to 261, because its max temp, with the top down the unit will try and not be able to cool the open cabin to the set temp on the display.

this seems to be on that will escape me until winter time... of cousre im in texas, arizona and nevada for the next few months.