Справочник Пользователя для Friedrich PTAC - R410A

NOTE:  System  operating  pressures  must  be  near 
normal before valve can shift. 

REVERSING VALVE DESCRIPTION/OPERATION  

The Reversing Valve controls the direction of refrigerant fl ow 
to  the  indoor  and  outdoor  coils.  It  consists  of  a  pressure-
operated, main valve and a pilot valve actuated by a solenoid 
plunger. The solenoid is energized during the heating cycle 
only.  The  reversing  valves  used  in  the  PTAC  system  is  a 
2-position, 4-way valve.

The single tube on one side of the main valve body is the  
high-pressure  inlet  to  the  valve  from  the  compressor.  The  
center  tube  on  the  opposite  side  is  connected  to  the  low  
pressure  (suction)  side  of  the  system.  The  other  two  are  
connected  to  the  indoor  and  outdoor  coils.  Small  capillary 
tubes connect each end of the main valve cylinder to the “A” 
and “B” ports of the pilot valve. A third capillary is a common 
return line from these ports to the suction tube on the main 
valve body. Four-way reversing valves also have a capillary 
tube from the compressor discharge tube to the pilot valve. 

The piston assembly in the main valve can only be shifted  
by the pressure differential between the high and low sides       

of  the  system.  The  pilot  section  of  the  valve  opens  and 
closes ports for the small capillary tubes to the main valve  
to cause it to shift. 

Disconnect  power  to  the  unit  before  servicing. 
Failure  to  follow  this  warning  could  result  in 
serious injury or death. 

TESTING THE COIL 

The solenoid coil is an electromagnetic type coil mounted 
on the reversing valve and is energized during the 
operation of the compressor in the heating cycle.

1.   Turn off high voltage electrical power to unit. 

2.   Unplug line voltage lead from reversing valve coil. 

3.   Check for electrical continuity through the coil. If you 

do not have continuity replace the coil. 

4.   Check from each lead of coil to the copper liquid line 

as it leaves the unit or the ground lug. There should 
be no continuity between either of the coil leads 
and ground; if there is, coil is grounded and must be 
replaced. 

5.   If coil tests okay, reconnect the electrical leads. 

6.   Make sure coil has been assembled correctly. 

Unplug  and/or  disconnect  all  electrical  power 
to  the  unit  before  performing  inspections, 
maintenances or service. 

Failure to do so could result in electric shock, 
serious injury or death.

NOTE: Do not start unit with solenoid coil removed from 
valve, or do not remove coil after unit is in operation. This 
will cause the coil to burn out.

CHECKING THE REVERSING VALVE

 

NOTE: You must have normal operating pressures before  
the reversing valve can shift.

Check  the  operation  of  the  valve  by  starting  the  system 
and  switching  the  operation  from  “Cooling”  to  “Heating” 
and then back to “Cooling”. Do not hammer on valve.

Occasionally, the reversing valve may stick in the heating 
or cooling position or in the mid-position.

Sealed Refrigeration System contains refrigerant 
and oil under high pressure.

Proper safety procedures must be followed, 
and proper protective clothing must be worn 
when working with refrigerants.

Failure  to  follow  these  procedures  could 
result in serious injury or death. 

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