11
Reversing Valve
In heat pumps, changeover between heating and cooling modes is
accomplished with a valve that reverses flow of refrigerant in the
system. The reversing valve solenoid can be checked with the
power off using an ohmmeter. Check for continuity and shorting to
ground. With control circuit (24 v) power on, check for correct
voltage at solenoid coil, and for burned or overheated solenoid.
With unit operating, other items can be checked, such as frost or
condensate on refrigerant lines.
Using a remote measuring device, check inlet and outlet line
temperatures. Do not touch lines. If reversing valve is operating
normally, inlet and outlet temperatures on appropriate lines should
be similar. Any temperature difference would be due to heat loss or
gain across valve body. Temperatures are best checked with a
remote reading electronic--type thermometer with multiple probes.
Figures 9 and 10 show test points on reversing valve for recording
temperatures. Insulate points for more accurate reading. If valve is
defective:
1. Shut off all power to unit.
2. Remove all charge from system.
3. Remove valve using a tubing cutter.
4. Install new valve (wrap valve with a wet rag to prevent
overheating while brazing).
5. After valve is brazed in, check for leaks.
6. Evacuate and charge system. Operate system in both modes
several times to be sure valve functions properly.
LEGEND
TP —
Test Point
A07433
Fig. 9 -- Reversing Valve
(Cooling Mode or Defrost Mode, Solenoid Energized)
LEGEND
TP —
Test Point
A07434
Fig. 10 -- Reversing Valve
(Heating Mode, Solenoid De--energized)
38Q
RF
