change bd50 for bd35

[Curt]

"I have a Technautics Cool Blue system that I replaced the origanl BD35 with a BD50. The original BD35 would take the holding plate down to -7 F, which is the freeze point for the eutectic fluid. The new BD50 will only take the holding plate down to 1 F. Old compressor had approx 100,000 hours on it.High pressure is 135 PSIG and suction pressure is between 0 and 2 PSIG. System was vacuumed for roughly 3 hours before re-charging with 134. BD50 continues to run as the set points for low side deadband is -10 F. Using a 690 ohm resister for speed controal at 3,00 rpm and/or no resisiter for 2,000 rpm, No change with either speed.When recharging, no bubbles show in receiver.Any clues why the new compressor won't go down further? Can use all the help I can.Curt"