compressor unloading

[hvac17011]

can someone explain what is actually happing inside compressor when compressor unloads. was working on large trane tin can. it had solenoid inside
cover.when compressor loaded suction went down amp draw up but never totally understood what happens intenally. i guess refrigerant is being bypasses internally. any tricks to troubleshoot/repair. anybody know of any good compressor schools.

[coolerinfrederick]

whats the compressor type, model #, probably either the hot gas bypasses and dumps back into the suction side, or a piston blocks the suction not allowing the compressor to pump any refrig. thus not doing any work. thats about as simple as i can describe it

[Dallas Duster]

It`s kinda like a Dodge MDS engine. When your in the city it uses half of it`s capacity let`s say it`s a 6 cylinder . 3 in the city and 6 on the highway.

[Octopus]

It depends screw most via slide valve, semi hermetic have a few different ways, Centrifugals by freq and turning vanes modulation etc...........

[supertek65]

semis use either hot gas bypass which is inefficient or suction unloading
both can be operated mechanically, electric unloader, pneumatic unloader or oil pressure unloader.
i have not seen one but i have heard of some machines that LOAD when powered up????
i know that on trane E compressors that operate with oil pressure that they start UNLOADED

have fun





It depends screw most via slide valve, semi hermetic have a few different ways, Centrifugals by freq and turning vanes modulation etc...........

[jpsmith1cm]

http://www.hvacrinfo.com/ae_index.htm


Scroll down to section #21.

There you will find Copeland's AE bulletins on capacity control.

[supertek65]

hi JP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:c ouch:

i would like to unload a couple of my daughters!!!!!!
they are a pain in the arse:eek2:



http://www.hvacrinfo.com/ae_index.htm


Scroll down to section #21.

There you will find Copeland's AE bulletins on capacity control.

[absrbrtek]

In a nutshell, the compressor is moving less volume of gas as it unloads. Be it by frequency, guide vanes, slide valve or rendering a few cylinders out of action. JMHO