Anyone else had a problem with the A/C? It blows hot air out at all temperatures except when it’s on “Low”.

Was working fine until yesterday.

Thoughts ? It’s a 2019 GLE 450

Mine did it for the first time yesterday and even on low - others have reported this issue. The fix was to turn off the car and restart and that worked with mine.

Mine was just diagnosed as having a failed "overhead control unit". Replacement part is on order.

Thank you for posting, I think I found some more info detailing the issue:
The Auto Climate Control (ACC) Air Temperature Sensor (N70/b1) in the Overhead Control Panel (OCP) (N70) often fails and causes the ACC to malfunction. This is easily diagnosed by utilising the ACC Hidden Menu Feature (See Automatic Climate Control (ACC) Service Menus which allows an access/review/read of the ACC actual parameter values during normal operation. Parameter NR.01: In Car Temperature Sensor (N70/b1), ACC Overhead Control Panel (OCP) (N70) should indicate the in cabin air temperature near the roof of the vehicle, eg 27C. If it reads 0C and the cabin is not freezing then there is a fault. The solution is to test the thermistor and aspirator function and then if necessary replace it. As this sensor is very similar to the In Cabin Air Temperature Sensor (N22/b1) in the Pushbutton Control Module (N22) see section Testing - In Cabin Air Temperature Sensor (N22/b1). To replace it see section DIY Procedures - Overhead Control Panel (OCP) (N70) below.

In this instance, I suspect poor build quality. Why? Giving the upper control unit a gentle whack with the palm of the hand while the A/C is pumping out hot lava when set to 16c results in it immediately working properly, at least for a while... loose connection is my best bet, closely followed by poor soldering on the NTC thermister.

I'm tempted to pop the panel out and check the connections, but you know, warranty.... so MB can replace the whole unit.

Facing the same issue intermittently on the same car. Gave the car to the dealer for repair yesterday, and now they can't reproduce the issue. Smh, had purchased the car just 10 days back.

Glad I found this as I'm having the same issue. Gonna take it in after I get fully vaccinated (have a couple recalls as well, and a headlight with water in it).