Deep vacum problems

[Blaster]

Hi there the suction temp from the second stage HX is around -95c

Suction temp -95, so inlet on HX will be a lot colder than that. Make the 2nd stage warmer will help with oil management problems on 3rd stage. R14 will condense at very low pressure below -100.
Also would cut cap tube to 1,7 mts of 0,9mm id cap tube.

Have you tried to switch off the 2nd stage compressor while running the 3rd? Try it if you havent tried it before, this will unblock the cap tube. Just make sure you watch the pressure gauges, also is a good way to test the pressure cut off...

[sacha35]

Suction temp -95, so inlet on HX will be a lot colder than that. Make the 2nd stage warmer will help with oil management problems on 3rd stage. R14 will condense at very low pressure below -100.
Also would cut cap tube to 1,7 mts of 0,9mm id cap tube.

Have you tried to switch off the 2nd stage compressor while running the 3rd? Try it if you havent tried it before, this will unblock the cap tube. Just make sure you watch the pressure gauges, also is a good way to test the pressure cut off...

Thanks for the info balster, i have tried what you said about running 3rd stage when second stage was at -40c and all works fine, eveap gets very cold nice and quick but as soon as the second stage hits -70c the cap tube blocks on the 3rd stage.

Will make the second stage warmer to around -80c on 2nd stage and try some 0,9 cap tube for the 3rd stage.

Thanks again for the info.

[Blaster]

0.036'' cap tube is the same as 0,9mm i think , 2,3mts is not short for the compressors you are using

R14 is very harsh on oil management, you can also try adding 5% of a oil carrier, r290 or r600a will improve oil circulation