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cro valve

Good Morning! Setting the CRO is for just after a defrost cycle or when first starting the unit or restarting the unit after a shut down. Once the comp's inlet press and the evap press are within 2psi [typically] of each other then charging and pressurers are done the normal way.If charging weignt is stamped on the unit ,no problem.If this is a split system ,then the superheat and subcooling is the way to go.Installing a sight glass/moisture indicator and charging by the "full glass" or "close to full" will get you close for starters,then adjust the charge as needed.The head press should not go above a corresponding saturated condensing temp of 125* F for starters[gauge temp],unless the cond entering air temp is 95* or hotter!Enjoy your day!


  • dmy hvac
    dmy hvac Member Posts: 33
    cro valve

    was wondering if anyone could help me out with how to set and adjust a cro valve i know they are used in systems with cap tube (freezers)but is there any other purpose for them?when i adjust it clockwise the the hi side and low go how do i figure` out if its low on freon.any help would be appreciated!
  • Techman
    Techman Member Posts: 2,144

    Hi!The CRO keeps the suction press entering the comp from being too hi,the higher the suction press the higher the amp's.So ,first you have to find out the comp's Full Load Amps -FLA-,then, either, from a warm box pull down or right out of a defrost cycle,you adjust the CRO to bring the suction press up or down to control the comp's amp's.The running amp's are not supposed to go higher than the FLA for the comp.And the CRO can also be used on TXV systems.I also record the corresponding inlet suct press of the comp to make it easier to readjust the CRO in the future,in case others get their fingers into the pie! Good Luck!
  • dmy hvac
    dmy hvac Member Posts: 33

    thank you!so i set it by the fla so what ever the suction pressure and head pressure are doesent really matter to a certain extent?heres my dilima how do you charge the unit if i cant really go by preesures????thanks in advance!!
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