High head pressure during defrost Hubbard 460 a

[kool moves]

Hi I have a Hubbard 460a which has a very high head pressure during a defrost and trips out on hp, I have recently changed comp as not pumping. I have checked the defrost check valve in the evap and appears ok, has anybody else come across this problem as not sure what else to check, could be a blocked evap or capillary tube both not easy to diagnose with out changing them.

[charlie patt]

how long does it take to trip and what is coil termination temperature have had issues with check valves evap probes faulty causeing high coil temp and high suction pressure or cpr set incorectly did you carry out a flow check?

[wilt]

there is a check valve in the condensor that has a,i think about a 2-3mm bleed hole in it might have some debris clogging it, cant remember the exact location of the valve but im think it was on the liquid line i do remember the that fault your describing as i came across 10 valves wrongly fitted & had to drill the holes in the check valve plunger!

[kool moves]

hi wilt thanks for the info but the gah units have a hole in the check valve not hubbard they use a capillary tube to bypass the check valve,
there is a check valve in the condensor that has a,i think about a 2-3mm bleed hole in it might have some debris clogging it, cant remember the exact location of the valve but im think it was on the liquid line i do remember the that fault your describing as i came across 10 valves wrongly fitted & had to drill the holes in the check valve plunger!

[kool moves]

hi charlie i have checked the check valve in the evap and that is ok, it takes a little while to trip and the defrost termination temp is set at 10 degrees.thanks for you info tho
how long does it take to trip and what is coil termination temperature have had issues with check valves evap probes faulty causeing high coil temp and high suction pressure or cpr set incorectly did you carry out a flow check?