Dual climate control outside temperature always reads 140

If the driver's blend door actuator has failed completely, or the wiring to it is damaged, you will not hear any clicking. Check for appropriate voltage at the blend door actuator, and determine from there if it's the actuator or the control unit.

unfortunately the climate control system in your car is totally electronic. the outside temperature system is related to the other problems, most likely there is a problem with the climate control computer, but it could be many things in the system that has gone haywire, there is not any thing you can do to the system with out a scan tool, you might be able to go to autozone and see if they can retrieve the trouble codes from the climate control computer. but not all autozone's can get info from Mercedes-Benz they are kind of a breed of there own, good reliable cars but very difficult to work on and Mercedes very reluctant to give any info on their computer systems to anyone other then there certified dealers.and if you are not very careful with the electronics you can do even more damage they are very sensitive to static electricity.i would not recommend trying to repair the system yourself......sorry

That is two separate problems. The "Flickering" of the outside temperature thermometer might be normal to some extent. Sometimes, the voltage from the sensor is at a point where it could be say, 31 degrees F or 32 degrees F. The display may flicker back and forth between 31 and 32 very rapidly until the voltage changes just enough to go make it go solid one way or the other. It probably does this all the time, but you didn't notice until you were paying attention to the temperature problems inside the car. (One actually has absolutely nothing to do with the other.)

The cracking and popping noises you are hearing from the temperature door and the difference between the temperature on the driver's side and the passenger side are the same problem. Apparently, you have dual zone climate control. This is usually caused by one of the temperature doors sticking and either stripping the gears inside the door control actuator or breaking the door itself. If you have both sides set at "HOT", the side that is cold is your problem-child. This will usually also set a fault code in your climate control module and may make your climate control display flash. (but it doesn't always flash when there is a code present)

The ambiant temperature sensor has malfunctioned.Replacing it should take care of he issue.

try this, disconnect the battery negative cable for 5 minutes and reconnect, this reset the climate control system in most cases, it is out of sync, this is a common problem on all late GM cars and trucks with dual climate control, if this doesn;t work u may need to replace the air temperature control blend door actuator for whoich ever side u can't control the temeperature on, if that is the case here.

you need to replace the ambient temperature sensor or do the math

Location is behind the plastic air dam that forces air from underneath the car to go up and into the radiator (directly in front of a/c condensor). It's somewhat of a tight space, however you can pull it with force off the plastic air dam it's connected to (about midway down) and then unclip the sensor from the harness. Just don't pull too hard once you free it from the plastic air dam. These sensors rarely need replacing. If your Dual Digital Climate Control System is giving you an incorrect reading on the display for the outside air temperature, this indicates a couple of possibilities. 1.)The sensor tip is dirty and should be cleaned, or 2.)The green or white wire that goes to this sensor is worn or has broke somewhere before the sensor. This happened to mine (green wire broke) and would always give an incorrect outside air temp. I fixed the green wire and now the system functions correctly again.

The sensor is located near the hood latch area in front of the radiator. If the temp is reading incorrectly, chances are it is defective. You can purchase a new one, they relativly inexpensive.
Disconnect the electrical connector then remove the sensor.
Good luck, let me know.
Regards,

Electronics involved !
The climate control seat system is able to heat and cool the front seats. Each climate controlled seat is operated by push-buttons on the dual automatic temperature controller (EATC) located on the instrument panel. Each front seat temperature is then monitored and controlled by the dual climate control seat module (dual CCSM) located underneath the passenger front seat cushion.

Both the driver and front passenger climate controlled seats are independently controlled electronically by the dual climate controlled seat module (CCSM) mounted to the bottom of the passenger seat cushion. The climate controlled seat system only operates with the engine running, however, if using a diagnostic tool to command the dual CCSM, diagnostic testing can be carried out with the ignition switch key ON engine OFF (KOEO). The system receives power from central junction box (CJB) fuse 118 (30A) through circuit 1153 (RD/BK) feeding battery voltage into dual CCSM C3265b pins 1 and 24. If power is disconnected from either pin 1 or 24 of dual CCSM C3265b, only 1 seat will be disabled (pin 1 for driver seat, pin 24 for passenger seat), the other will remain operational. Since both climate controlled seats operate independently, if a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the module and the other will remain operational.

Sorry , but it would be best for you to take it to the dealer or someother qualified repair shop.

it may afect the climate control to operate right,
try to locate the temperature sensor than most times is in the lower side of the wilshiel and on top of dash board and see what happend