Both the EPR and the 2-way solenoid valves are
normally closed, so the EPR must be powered
only during refrigeration and the 2-way valve
only during defrost.
The 3-way valve is normally in refrigeration
mode. Energizing the solenoid opens the pilot
valve port which directs high pressure Koolgas
vapor to the piston chamber. Pushed to its
opposite position, the piston assembly stops the
suction line and opens the Koolgas line. A bleed
port in the piston provides for de-compression of
the piston chamber when the pilot port closes.
Table 6-2 — Troubleshooting Koolgas Valves
September 1, 1997
P/N 401789
6 - 3
HUSSM ANN CORPORATION • BRIDGETON, M O 63044-2483 • Printed in USA
From Koolgas
Manifold
To Evaporator
To Suction
Manifold
Defrost
Refrigeration
Figure 6-4 — 3-Way Solenoid Valve
Malfunction
Cause
Action
Fails to Open
Dirt plugging pilot port
Disassemble and clean
Solenoid not energized
-bad solenoid
Replace solenoid
-circuit open
Find and repair open
-NOT in defrost mode
Correct defrost clock problem
Fails to close
Piston port plugged
Clean or replace
Barrel or piston scored
Replace
Dirt in piston chamber, causing drag
Clean or replace
Stuck in defrost mode
Correct defrost clock problem
To Evaporator
From Koolgas
Manifold
Figure 6-3 — 2-Way Solenoid Valve
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