I have two alarms going off and shutting the chiller down, t999 and t998 both are for "loss of refrigerant flow" one in circuit a and one in circuit b. According to the history it just started happening the other day, the liquid line filters are good ,suction valves are open and I am getting real good flow for the chilled water. Each circuit runs for approx. 3 mins and then they trip off with this alarm. Both EXVs are frosted up after they trip off.

Has anyone seen this before, I find it strange both circuits are acting up at the same time... Telling me it's some thing that affects both ie: chilled water etc

Any help is much appreciated