Ml350 2008.
wasnt cooling efficiently, and the electric fan had been running very high.
my researched pointed to the pressure sensor switch.
prior I checked the Freon and it seemed to by fine.
I replaced the switch,
evacuated the system and checked for leaks.
and it is perfect.
I fired it up turned on the ac
took the 1st charge with no issues,pressure was only at 30.
I connected the 2nd can the pressure shot up
to 70lbs red zone on my gauge..
I connected a 2nd gauge to confirm.
what I noticed is when the fan kicked on that’s when the pressure shot up.
the air is blowing hot, so it needs more charge.
any thoughts?

 

So you replaced the Pressure Sensor (not a switch) on your research and that didn't fix the problem.

The cooling fan will run at high speed once the A/C Control Module recognizes a problem, and will prevent the compressor to actuate.

What you should have done originally, was check for codes in the AC system.

 

I did scan it there were no codes

 

I did Scan it, There were no codes.

 

Randy, if you only have a code reader, you will not be able to read codes in the AAC Cont. Module. The codes will be stored here.

 

I would suggest you stop charging the AC based on pressure readings. The correct way is to do an evacuation and refilling by weight.

Good luck.

 

Ahhh…. What is the procedure for doing that?

 

You need a scanner type reader that will show codes in all and every 25 modules.