Friends,

I'm looking for some help on a 2011 GLK 350, 19,000 miles.

Picked this thing up a few months ago and it's a beauty but the Air Conditioner is intermittent cold air output. Some days it's good, some day's bad. Some mornings good, some evenings bad.

Blower fan, all good. Only 2 ounces low of refirgerant, and no leaks. I'm thinking possibly an evaporator sensor or so.

Any thoughts? Location of sensor? Worth changing? Name brand?

Thanks,

Strick

 

"Sometimes" on auto the aircon needs to detect more than a 3 degree difference between outside and inside air - I am not saying that is your problem - but others who encounter this "dial down" the climate control to "kick in" the air con - then reset back up to their preset temp...

 

You say 2 oz low, where did it go. If any moisture got into the system, the expansion valve may be freezing up. You should have a complete AC evacuate and refill. But first check the compressor wiring and the connectors under the hood. You may just have a lose wire or a corroded computer connector. If you can catch it when it is not working, go under the hood with the engine running and wiggle the wires and connectors to see if it kicks in the compressor clutch.

 

Welcome their advice sounds good

 

Thanks my friends. I'll certainly try the suggestions.

 

Brought the GLK to the shop today. Mechanic said the compressor was going out. We drained all refrigerant, then filled to the dead on correct level. Still the same issue... New compressor next I guess. Dryer? Manifold? Wow these cars are troublesome...


Anyone else with such problems?

 

If you put the temp control to minimum, and then have someone turn the AC on and off, can you see the clutch pull in every time? Compressors, themselves, mainly either work or don't. Rarely is the compression intermittent. The clutch, on the other hand, can easily be intermittent due to the wires in the electro-magnet shorting or going open with heat. This could be outside heat or heat generated in the clutch. An A?C shop would put a pressure gauge on the high side and insure that the compressor is actually making high pressure when the clutch is engaged.
The expansion valve is the next trouble spot in the AC circuit. Any moisture in the system will cause problems. There is a dryer in the system to take out only a little residual moisture once the system is sucked down to a high vacuum. If the system had/has a leak the dryer will keep it working for a little while but then be come with moisture. It should be replaced. The vacuum step is very important in the refill. You should not just add refrigerant to the system with out evacuating it first.
The final place to look is the control flaps. If the evaporator line gets cold, but you don't get cooling in the car, one or more of the vacuum operated flaps under the dash is not opening.
There are plastic arms on vacuum and servo motors that move flaps to direct the heat and AC to the correct outlets. In previous MB models these were know weak spots. I would insure that the air is being forced through the evaporator and then out into the vehicle before looking elsewhere. When you turn off the AC can yu hear a difference in the air flow, while the AC appears to be inoperative?

 

Doesn't sound "right" - might be - something sounds off that a deeper diagnostic would uncover..

 

Compressor was shot. I changed it and the dryer. All problems are now fixed.