Quote Originally Posted by DetroitAC View Post
correct me if I'm wrong sweeper, but you've got a temperature of 4.1C after the bulb? That's not the same as a superheat, unless you're using a T1-T2 function on the TC reader (doesn't look like it based on the LCD). Based on your gauge reading, I'd say you still have 20~30C superheat. You should keep adding charge until you get subcooling (got a sight glass?)

Your compressor will be hard to start with R507 because it's an R134a compressor AJA2419YXA. Y=R134a code, Z=R507 code

R134a uses a lot more compressor displacement per motor power than R507 does. In the case of that compressor, Tecumseh makes the same compressor for R507 AJA2419ZXA, and my guess is it has the same compressor parts with a (more powerful) motor more suited to R507.
Yes, 4.1C was after the bulb and I was using T1 function. I also have a sight glass and its almost filled solid, except for a little circulation. I agree it could use more refrigerant, but I think I should wait to add more refrigerant once I get the cooling chamber system operation with heat load to tune both systems without overcharging. The gauges are within 10 psi of being even pressure and the compressor starts fine now. I'm in the process of insulating and its real pain, because I didn't allow enough clearance between the lines.

If this compressor fails to do the job....I have a back up plan to use a low temp 1 HP compressor made for R507. I also have a low temp 2 HP compressor, but I'm sure this monster would be overkill.

Thanks again guys for your comments and I will keep you up to date with progress.