Quote Originally Posted by mad fridgie View Post
Using a bigger motor on the same displacement will surfice as far as overloading.
Regarding other issues, this is dependent on the type of compressor, your compressions ratios are much lower, which in itself is good, but how the discharge valves handle the small ratio, may cause the valves to bounce (extra fatigue), this is to do with spring strength.
Without testing (which you should do) my gut feeling would be at you descibed conditions that it would be OK.
I assume that compressor is a fool and It didn't know what it's compressing. but the motor is quit clever for the load and temp. When I tested it, it strikes when the discharge is about 105 c as well as suction temp is 48 C. What confused me is that the current draw is only 6.4A(whose rated current is 6A for R407c). the Pd is 24 barg and Ps is 5 barg for R134a(I use R134a in this R407c compressor).

I guess it's because the R134a's flow is smaller than that of R407c so the motor's heat can't be controlled to a safe level before it triggered the motor's temperature switch.

Is it true? or somethings else missed?