internal compressor valve or TXV

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internal compressor valve or TXV

Postby rani » Sat Jul 09, 2011 5:37 pm

Internal Compressor valve vs thermostatic expansion valve causing no refrigerant to take up? I had two different technicians come out and the first one was newer. He said the problems seems to be with the internal compressor valve because here are the gauge - discharge pressure is 225 psi, suction scale decreases down to 15 & the compressor shuts down. When pressures equalize, compressor starts again and it keeps cycling. He tried to put refrigerant in and the system wouldn't take. The 2nd technician said it's the thermostatic expansion valve that can prevent the refrigerant from being taken into the compressor/system. Which way do you think it is? Would the readings be any different if it was the expansion valve vs internal compressor valve?
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- internal compressor valve or TXV

Postby specialtyclimate » Sun Jul 10, 2011 8:22 pm

Definetely not the compressor valves, when they go bad the pressures will be the same, or at least close. and also the amp draw will be lower. if it's pumping down its most likely the txv. or a plugged filter drier..
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- internal compressor valve or TXV

Postby nomadpeo » Mon Jul 11, 2011 12:16 am

it is probably shutting down on a low pressure cutout control which is there to do just that if the low pressure drops out of safe range. it is most likely the metering device if you do indeed have a txv type. if the power cap has lost its charge, the system will pump into a vacuum. the technician will need to bypass the low pressure switch to observe whether this is happening. at the same time, the subcooling can be calculated to rule out low freon. if the valve itself is restricting partially, the discharge would rise abnormally as the suction falls abnormally.

the other possibility,as mentioned is a partially or fully restriced liquid line filter drier. this can be determined by allowing the unit to run and looking for a temperature difference across the filter with a strap on or clamp type temperature probe. if it is totally restricted, frost will be evident on the leaving side.

the compressor is pumping fine.
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