TK 61555-2-MM-EN
83
Three-Way Valve Condenser Pressure Bypass Check Valve
A three-way valve condenser pressure bypass check valve is used in this unit. This check valve
controls the bypass flow of refrigerant gas between the condenser inlet line and the compressor
discharge line.
The check valve is closed when the unit is running on cool, or whenever the discharge pressure is
higher than the condenser pressure.
When the unit is running on defrost or heat, if the condenser pressure is higher than the
discharge pressure, the check valve opens and the condenser pressure is bled off until it drops to
the level of the discharge pressure. The purpose of the valve is to improve the three-way valve
response time when shifting from heat to cool.
If a three-way valve does not shift back to cool immediately after the pilot solenoid closes, and
finally shifts to cool when the temperature rise puts the unit into high speed, the three-way valve
end cap should be checked. See
“Three-Way Valve Repair,” p. 103
in Refrigeration Service
Operations.
Check the operation of the condenser pressure bypass check valve as follows:
1.
Remove the condenser pressure bypass check valve cap from the three-way valve.
2.
Using a screwdriver, gently turn the check valve stem in until the valve is front seated.
3.
Install a gauge manifold set on the compressor.
4.
Close (front seat) the receiver tank outlet valve.
Figure 63.
Three-way Valve Condenser Pressure Bypass Check Valve
1.
Check Valve
2.
Heating/Defrost Position
3.
Cooling Position
