My climate control system was essentially useless until I took out the glove compartment and replaced the disintegrated connecting tube between the air temp sensor and some pipe that appears to have the purpose of pulling air through the sensor.
The glove box comes out by removing the center locking pin from each fastener, and then pulling out the fasteners. You have to manipulate the glove box courtesy light somewhat as you're pulling out the glove box in order to separate it from the glove box or disconnect its leads.
You will probably find a foam tube that looks something like pipe insulation. Or the remains of it. I cleaned all the remains away and replaced this section of foam tubing with 3/4-inch heavyweight "agricultural" rubber pipe (a lot like a car's heater hose in construction). Cost about $1.50 at a farm supply store. The 3/4" pipe provided a snug fit to the plastic pipes of the climate control system. I cut it a little longer than necessary, ran it up over one CC pipe way back, and then pulled it onto the other CC pipe. That way I have good overlapping connections that help the system stay relatively airtight. I didn't see any need for gasket shellac or hose clamps. It just has to pull a little air through the sensor.
Results are incredible now. I can set the temperature dial somewhere and the interior stays at that temperature. What a concept!!! Why MB used that cheap foam pipe I'll never know.