The compressor does not need to be turning to check static pressure. Static pressure will always be a little over 80 pounds if there is ANY liquid refrigerant in the system at all. Since you are reading 44PSI, the system is virtually empty.
The a/c system does not USE refrigerant like an engine uses oil. If it is empty, this means you have a leak. You will have to find the leak, repair it and recharge.
I am not a fan of converting to r134, but since it is an r134 system, this makes it a little cheaper to find the leak. Go find a can of r134 UV dye and charge the system. Once you put in as much refrigerant as it will take without the engine running, you will have enough pressure to actuate the low pressure switch and kick in the compressor. After you have run it a little, use a black light to search for the leak. If you don't readily find the UV tracing anywhere under the hood on lines, receiver, condensor, compressor, etc. then run the system enough to get condensation to drain underneath the car. Use the black light to look at the condensation water to see if there is any UV dye present. If there IS UV dye in the condensation water, then the leak is in the evaporator. If there is NOT, then gain access under the dash and look for UV dye traces around the evaporator connections and the expansion valve.