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Salvapan
05-10-2009, 03:57 PM
My head pressure regulating valve keeps closing on me and does not allow liquid refrigerant to pass through. Just a little gas passes and just makes my TXV valve whistle. Futhermore, my system runs and then ices up half of my evaporator coil and then i get this problem with my pressure regulating valve. Any suggestions? I changed the valve already once and it still does the same thing.
nike123
05-10-2009, 05:59 PM
Do you have refrigerant diagram? What is valve model#?
R. skiffington
06-10-2009, 08:14 AM
what Refrigerant? What HP are you trying to sustain? At what pressure is the valve closing? it looks like the problem with the valve is a symptom of another problem in the system, is the HP dropping too low at some stage, are you sure the TX valve is operating correctly?
Sandro Baptista
06-10-2009, 10:10 AM
My head pressure regulating valve keeps closing on me and does not allow liquid refrigerant to pass through. Just a little gas passes and just makes my TXV valve whistle. Futhermore, my system runs and then ices up half of my evaporator coil and then i get this problem with my pressure regulating valve. Any suggestions? I changed the valve already once and it still does the same thing.

Ensure first if you have liquid subcooling at the head of the TXV, or at least no flash gas.
Salvapan
07-10-2009, 02:55 PM
My refrigeration system is a 7.5 hp 404A low-temp system. My pressure regulating valve is a OROA-5-180. I have two other identical units installed the same and they work perfectly. I thought i had moisture in my system and i vacuumed to 500 microns, charged up my system back and it worked perfectly for two days. I got a call this morning that the unit is up to 20 degrees F and the unit is just running, no cooling because the pressure regulating valve is not opening and the TXV valve is just whistling. Am desperate now.
goshen
07-10-2009, 09:21 PM
dDo you have refrigerant iagram? What is valve model#?
answering this question will let us try and help i cant guess what u have there only assume and we all know what that stands for!!!:cool:
R. skiffington
08-10-2009, 08:23 AM
You could always remove the valve alltogether and use a pressure switch to cycle a condenser fan to control the head pressure, this will prove whether it is definitely a problem with the valve.
nike123
08-10-2009, 10:15 AM
REFRIGERANT CHARGE AND CHARGING PROCEDURES
— When this method of head pressure control is utilized
on a system, there must be enough refrigerant to flood
the condenser at the lowest expected ambient and still have
enough charge in the system for proper operation. A shortage
of refrigerant will cause hot gas to enter the liquid line and
the expansion valve, and refrigeration will cease.

http://sporlan.jandrewschoen.com/90-30-1.pdf