300 SEL No cold air

[acerejo]

Hi everyone,
Recently had system converted to r134 including replacing compressor.
System is fully charged the compressor comes on the high and low pressure looks good but only ambient temp air comes out of the vents and compressor kicks off after a couple of minutes. Had a garage look at it and said this is a job for a benz dealer probably some sensor.
I would like to try to trouble shoot this before I subject myself to the mercy of the dealer.
Is there any sensor that I can jump or bypass to trouble shoot this myself.

Any help would be appreciated.

Thanks
Armind