Dear all,
I would appreciate some advice as to whether I may have a problem with my air conditioning or whether the following is normal operation:
I recently drove through France in 40 degree Centigrade temperatures for around 6 hours with the A/C on all the way. Suddenly the front blowers stopped outputting air almost completely (even on full fan) and only the rear blowers had any power. I switched off the fans all together and waited still a stop about an hour later. When I turned on the fans then, everything worked again, though I noticed large amounts of water coming from under the car on both sides towards the rear of the engine bay which gradually slowed to a slow drip. This tasted like pure water. I am assuming this was the normal A/C condensate that somehow got backed up and was then expelled.
Since arriving at our destination I have been running the A/C and it has operated normally, though we have not done any trips over 1 hour.
My question is: does the A/C cut out automatically if over-used or this a sign of an impending problem I need to address?

If your evaporator freezes the A/C is designed to shut off to allow it to defrost and then it should cut back in the system is doing this all the time and that is where the water that drips is coming from, maybe due to the long use it needed to shut off for a bit longer than normal which you wouldn’t normally notice. L322 4.4 TDV8 Current
L320 3.6 TDV8 Going
L322 3.0 TD6 Gone
Disco 2 Td5 Gone
Defender 90 Gone
Freebie Td4 Gone
Disco 1 200tdi Gone

Unnecessary quote removed

Hi,

Sounds more like a fan issue and or plenum chamber valves. That, I dont know much about.

I have worked on Automotive a/c for 35 years though.

You will in high temps and humidity get lots of water (condensate) dripping off the evaporator(s) on your car.

However, if there is an issues with the refrigerant charge level or expansion valves, you may be getting localised ice build up, rather than condensate. That then melting into a large puddle.

The systems on modern RR's are electronically controlled using thermistors or (NTC's (Negative Temperature Coefficient)). These are electronic thermostats. These site in or on the evaporators to measure the temperatures to send information back to the climate control computer.

If these sensors fail, that too can shut down the a/c system (These were a common issue when Mercedes first started to fit electronic climate control systems).

Also included in the system are HP and LP switches. HP switches will shut down the system if the pressure in the high side side of the system gets too high (Condenser). This can be because there is not enough air flow over the condenser or if the fans have failed.

The LP switch will, or should, shut down the system if the pressure is too low. That is, if the refrigerant charge is too low or the outside temperature is to low (thats why a lot of systems on cars will not operate in winter)>

The first thing you need to get checked if you suspect its the refrigeration part of the system, is the refrigerant charge level.

If thats okay, its a case of scanning for error codes.

I hope this helps?

TM

Thank ypu
will check charge levels and error codes.

Charge level was down to a quarter. Been working without issue since (but obviously not been stressed by recent weather).