Problems in CBP compressor cooling unit

[wcam3]

Dear friends,
We have designed a chiller unit with a Tecumseh CBP compressor, rating 750 BTU. Of the three machines, one machine is working fine. Other two machines are taking too long to cool. I have replaced the synthetic oil in the compressor with mineral oil as we are using hydro carbon as refrigerant. The variation in the parameters are as follows

Discharge line temp in OK machine = 65 deg Centrigrade immediately within 5 secs
Discharge line temp in problematic machine = 40 deg after 10 mins

Condenser air flow temp in OK machine = 42 Deg
Condenser air flow temp in problematic machine = 30 Deg

What I could understand is that the system is not throwing out enough heat, but could understand where is the problem.

Please suggest trouble shooting options

Thanks and regards
Giridhar

[nike123]

Install some access valves and measure high and low pressure, temperatures of pipes after evaporator and condenser, discharge pipe, suction pipe near compressor and before expansion device, condenser air in and out temperature, water in and out temperature and give us full compressor model# and compressor current. Also, tell us what is refrigerant used.
Then we will probably know what is happening since we cannot be fisically there to see, touch, smell, hear and do that measurement instead of you.

Or we could guess like blind chickens in sand looking for worm and tell you that machine probably doesn't getting enough heat from evaporator or capillary clogged or something else.
So, give us full measurements!

Did you changed oil in all 3 units or only in problematic one. If later is case, you may have problem with mixing oils vax formation or oil viscosity.