Great to hear you found part of the problem.
Now that you have figured how the issue with the connections, maybe...?
If you have R134a charge port adapters on your old R12 service fittings you need to insure what kind they are. One type of adapter has a pin that pushes down on the schrader valve inside the old R12 service port. Another type of adapter has its own schrader valve and this means you have to remove the old schrader valve from the R12 service port before you install the R134a adapter on it.
There are 2 types of 'snap on' service hose couplers that you can put on your R134a service port adapters. One is simple like an air tool hose coupling, you simply pull back on its outer shell, put the coupler on the R134a adapter and release the shell. This type automatically pushes down on the valve or pin in the R134a adapter. The second type of coupler has a knob on the top. You turn the knob outward (CCW), pull back on the outer shell, put the coupler on the R134a adapter, release the shell, and then turn the knob inward (CW) and this knob moves a pin inside the coupler to push down on the pin or valve inside the R134a adapter.
Assuming you have the engine warmed up, at "idle", ac running for at least 10 minutes or so, windows up, temp set to max cold, no fresh air mixing with the AC air, ac fan speed 1 or 2, at 70F outside air temp:
1) You would expect to a high side more near 160 psi. You are seeing 125 psi. If you have a good compressor your present high side pressure suggests you are undercharged, not enough refrigerant.
2) Your low side, in a perfect world, would be 35 psi or near there with everything operating correctly; low side in a properly evacuated and charged system with 35 psi would reflect an evaporator core temperature of approx 37F.
You are seeing 50 psi which would reflect an evaporator core temperature of 45F . Usually, your AC vent temperature will be a few degrees warmer than the evaporator core temp. You can verify the AC vent temp using a digital thermometer in the vent, or if you can access the evaporator core you can put a probe in its fins.
Because of your low high side reading and high low side reading it sounds like you are undercharged and you have 'air' in the system. So, back to the original questions:
A)Whom evacuated and charged the system?
B) How much refrigerant in total did they put in?
If you do not pull a 'perfect vacuum', remove as much ambient gases (air) from the system, say down to 30" of mercury for simple terms, the excess air still in the system will prevent the refrigerant from operating correctly. Excessive air contains moisture. Moisture can freeze inside the expansion valve and cause a blockage, cause it to hang open or stay closed.
After you pull that perfect vacuum you need to have a idea (a bogey) of how much refrigerant your system needs to work properly. Let's say your 944 in the past used 2.25 lbs of R12 refrigerant; lets convert the rough pound measurement to ounces, 2.25 x 16 = 36 oz of R12 (you might have a refrigerant sticker somewhere in the engine compartment noting exactly how much). With R134a we usually use less refrigerant. A rough idea is 85% of the weight of what you had with R12.
So .85 X 36 would be about 30 weighted ounces. That is your bogey.
As you charge the system you have to observe and record how much refrigerant you are putting in. So, for example if you knew you put in the "bogey", or 30 oz in this example. And the outside air temp is 70F, and your low side pressure is too high, 50 psi, and your high side is too low, 125 psi That would suggest your compressor is weak (excessive slop in the piston/bores, problem with reed valve).
And, I'm assuming the observations of temperature and pressures you noted were when the compressor was operating; not static.
So, if you think you got your service hose coupler thing figured out, and you know whether or not someone pulled a good vacuum before they charged it.....
What do you think the issue is?
AC Help Basics