Copeland Scroll Compresor ZR 125

What does Copeland say on the topic?

TQ, Make sure the oil level, pump and KO are all working OK.

KO? Could u explain..tq

KO stands for Knock Out pot. Scroll compressor elements do not actually touch, but are sealed by a silicone based sealing lubricant. After the compressor discharge you will find a knock out pot which removes most of the expensive oil from the discharge air.

sounds like the internal relief valve is opening

....in which case the unit is up-to-pressure and doesn't need to compress any more air. Hence the curiosity about the manufacturer's comments earlier. If it is unloading and running on standby, waiting for the pressure to drop off again, it could be described as "normal operation".

what type of system is this compressor on? were you able to check the suction & discharge pressures during the short time it runs? what refrigerant is being used?

The unit is 3hp split system using R22. Actually when I first start up the unit, it runs properly until several minutes, then stop compress the refrigerant even the compressor is still running. When I OFF and ON the unit again the same thing still happen............

Which is the discharge pressure when it stop to compress?

If discharge pressure is too high scroll compressors have a kind of internal relief valve that open and allow internal by-pass.

Bye

framole

Copeland scroll compressor ZR 125. suction pressure 40 and discharge 220. After run for several minutes the suction pressure = discharge pressure, using R-22

the relief valve internal to the compressor is the most likley problem .Yes guages on the suct and disch are a must.It opens during operation if ther is no-or insufficient condenser(is the fan on ,or water flowing in the condenser?) otherwise the refrigerant flow regulator is plugged or if ther , a solinoid is not open to allow flow.Gages will tell the story

Sounds like the system is overcharged with refrigerant (Requires removing and weighing to check) or you have a high side blockage/us expansion device

A scroll can have a vacuum and/ or a pressure relief internal to its body. The necessary info. needed is :

1. Discharge and Suction pressures

2. Amp draw (actual) and rated @ design voltage

3. Head temperature

A diagnosis can then be accurately provided !

When the suction P is 40psi and discharge P is 220psi, the compressor stop compressing and Discharge P = Suction P

Diagnosis: Replace compressor.

Solution: Determine if any condition exists thet will cause high discharge pressures (over 425 psi) or a vacuum condition on the low side.

It seems that your unit was undercharge of refrigerant..add refrigerant and take your discharge pressure before condenser inlet..use a water hose to cool down the compressor and charge up to 48 psig and finish the charge topping without watering the compressor dome.measure the comp dome temp,it should go around 220 deg,F or below.same thing happened with my 125ZRK comp.now its working properly.and also consider restriction on your system.

The ZR125 like all the ZR series have an internal relief that will stop the comp pumping if dish temps or comp temp gets too high - silly idea.

Most likely cause of this problem is insufficient suction cooling.

remedy any condenser issues eg: fans / water flow etc

Check superheats and provide more return cooling - problem should go away.

From memory the relief triggers when disch temps stay above 110 - 120deg C

Hi there,

the problem is lack of refrigerant return causing the compressor to run with no cooling.

Check metering device and or a blocked drier or closed solinoid.