I am in the process of changing from R12 to R134a.

I have all necessary fittings, hoses, etc, and once I am sure of where the adapter goes, will place it and apply vacuum for 30 minutes before charging with 134a.

What I am not sure of is the location of the low pressure side fitting on the rear of the Diesel-Kiki AC compressor that is on the vehicle.

In the process of having the remaining R12 sucked out, it seems that the two fittings on the rear of the compressor are different size. The fitting on the service guage did not want to thread onto the upper left fitting on the back of the compressor. Grant you it is hard to get in there but even aligned it did not want to turn more than 1/2 turn then stopped.

The lower right fitting allowed the R12 service fitting to spin on without problem. The R12 was pulled out through that port.

I am concerned that the R134a adapter will not fit the present adapter at the upper left of the back of the compressor which being next to the large hose coming from the evaporator should be the low side port. This seems to be the larger of the two fittings and unless I just had too hard of a time aligning the threads, I am concerned the port will not accept the R134a charging fitting.

Will someone with familiarity with this process please provide me with some insight?

Thanks,

PS It hit 100 with an index of 112 about noon today so I would like to get this functioning as soon as possible.