CGAE pumpdown timer fault

[r404a]

CGAEC404, ser# J96M84073. circuit 2 frequently violates the pumpdown timeout circuit safety. never can catch it doing it and have changed out the LP switch thinking it was hanging up. Still happens and am about to change the liquid line solenoid valve out. anyone deal with this issue before?


r404a

[Gear-Drive Guru]

Just so that we are talking about the same machine is the CGAE a 2 circuit, reciprocating air cooled chiller with up to 2 comps per circuit? If so has it a RCM control module?

[r404a]

gear drive,
two scrolls per circuit


r404a

[jayguy]

just so that we are talking about the same thing...

While in pumpdown mode, the Low Pressure Cutout (LPC) did not open in 30 seconds so Compressor A was shut down anyway. LPC may be defective, LL solenoid valve either leaks or is not closing.

this diagnostic?

[r404a]

Thats it Jay. i am leaning toward solenoid valve intermittingly leaking by. I think I will change it out. thanks for the replies


r404a

[jayguy]

don't rule out a bad low pressure switch (or somebody is 'monitoring' it), solenoid valves that have been moved and they are farther away than normal, solenoid valves that have someone else controlling them (bad, bad BAS technician!), low to very low suction superheat or high head pressure possibly due to overcharge, non-condensibles, etc.

[r404a]

thanks for the input jay


r404a

[jayguy]

oh! and i thought of another thing last night...perhaps you have a compressor that is not pumping very well, especially at high pressure differentials.