TXV fault

[szbo_tomas]

Have the following problem
air cooled water chiller with r22 refrigerant, compressor is two stages 50 & 100%, two condenser fans set to start due to cond press as follow:
first fan on@12 bar, off@14bar
second fan on@19bar,off@14bar
when second fan start at cond press 19 bar and evap press 4 bar, immediately cond and evap press drop , evap press to 2 bar and cond press drop below 14 bar so after short time the fan stop, and both press for evap and cond goes up again, then fan is on again and so so
second fan is keeping turning on and off, and pressure for both cond and evap change widely up and down
superheat is high especially when comp is 100%, it reach 13 C
subcool is 9 C, and sight class is full
disch temp is 90 C
when copm goes to 50% superheat is good
I tried to open TXV very widly but no change on supht
I removed the sensing bulb from the suction line and wait for result, and problem dissapeared

Should I replace TXV???

Thank you

[frank]

first fan on@12 bar, off@14bar
second fan on@19bar,off@14bar

A classic case of incorrect settings causing the system to hunt.

Adjust the fan cycle pressure settings to smooth out the condensing pressures. Once the first fan comes on it should stay on and the second fan should cycle on/off with load.

I don't think this is a fault with the TXV

[szbo_tomas]

first fan immediatly on when chiller on and never off, so as you said second fan only will regulate the cond pressure
which I did not mention that the chiller has two circuit each with two fans, and the mentioned setting which is factory setting is for both circuits, but the problem is only with one circuit
with the other circuit when second fan on @ 19 bar cond press, that press drop down to about 16 bar and stay for long period at this

Thank you

[maddymoo2]

is water set temp within normal specs maybe stage 1 and 2 getting different loads