Frick rxf screw loads but won't unload

[nH3newbie]

Ok I'm currently wrking on getting this comp. Up n goin properly. Here's the current issue - it loads fine but whn in auto and signal is sent frm board to unload no unloading occurs. Evn in man. operation and I push man. unload on panel nothin happens! Iv checked voltage at directional valve all is wring properly (it's a brand new valve w new coils). Changed out indicator piston n spring new o rings and pot. Evn if I physically push on solenoid w a screw driver no unload. Machine loads and unloads through same oil line. Any suggestions??

[Magoo]

Hi nh3 newbie

Generally they are spring return/unload. Oil pressure loads and holds position and vents that line to suction and the spring return unloads compressor. Does it unload when stopped, if so then it would seem to be electrical.

[nH3newbie]

As a matter of fact yes, it does unload itself whn stopped

[Magoo]

Hi again nh3 newbie.
OK it unloads by itself when stopped, so the piping on hydraulic relay would seem to be correct. So would seem to be an electrica based problem. Either electrical or bleed to suction, the older ones had a bleed regulator from relay to suction, maybe too regulated, also a regulator valve between load slide and relay to limit unload rates, possible one or both, so when stopped no suppy oil it can unload normally.
Just thinking out load, hope this helps.
magoo

[serviceman]

what kind of panel is the machine? review digital output fuses, panel quatum lx, or quantum, an indicator of the slide valve operates correctly

[Grizzly]

Have you tried the below trick?


Solenoid may be mechanically actuated by inserting a piece of 3/16" rod against armature pin
and pushing spool to opposite end. Push YY1 valve to confirm unload capability. If valve works,
problem is electrical

Grizzly

[Lodiev]

Have you tried the below trick?


Solenoid may be mechanically actuated by inserting a piece of 3/16" rod against armature pin
and pushing spool to opposite end. Push YY1 valve to confirm unload capability. If valve works,
problem is electrical

Grizzly


And if this fails it is normally the seals on the hydraulic piston inside that's leaking from the discharge side to the oil side thus the pressure course it to stay in the loaded position wile running but unloads as soon as the compressor stops, even if the unload solenoid are not energized.

[serviceman]

put out of the machine, remove the pressure with a manual oil pump oil to the valve add it and check the calibration slide on the rear panel solenoid operated manually download

[Jason NH3]

IF, using an amp-probe you have verified that the machine is not un-loading (these older machines with the plunger type slide valve potentiometers on them are notorious for false readings) and the machine does unload when stopped then it is a pretty good indication that the slipper seals or glyde rings (same thing different name) are worn out, again a common problem on older RXF compressors. These are the seals that hold oil pressure against the capacity control piston to hold the slide valve unloaded. When worn bad enough the seals do not hold the oil in allowing discharge pressure to force the slide valve back fully loading the machine. The seals themselves are no big deal to replace and are not that expensive. When doing this repair I also recommend rebuilding the slide valve indicator assembly, there is a small brass rod, a spring, two O-rings and the potentiometer. The small o-ring that seals the brass indicator rod is notorious for leaking oil, this oil makes its way onto the potentiometer and will make them read erratically. Since this assembly has to be removed to service the glyde rings anyhow it is a must do in my opinion.

[zeh0085]

Have you tried to open the flow control valve on the unload side?