Friedrich VERT-I-PAK VHA-18K75RTP, Service & Parts Manual

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42 PB
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”. Rapidly cycle. Do not hammer on valve.
Occasionally, the reversing valve may stick in the heating or cooling position or in the mid-position.
When sluggish or stuck in the mid-position, part of the discharge gas from the compressor is directed back to the
suction side, resulting in excessively high suction pressure.
Should the valve fail to shift from cooling to heating, block the air flow through the outdoor coil and allow the
discharge pressure to build in the system. Then switch the system from heating to cooling.
If the valve is stuck in the heating position, block the air flow through the indoor coil and allow discharge pressure
to build in the system. Then switch the system from heating to cooling.
Should the valve fail to shift in either position after increasing the discharge pressure, replace the valve.
Dented or damaged valve body or capillary tubes can prevent the main slide in the valve body from shifting.
If you determing this is the problem, replace the reversing valve.
After all of the previous inspections and checks have been made and determined correct, then perform the
“Touch Test” on the reversing valve.
COMPONENT TESTING
Checking The Reversing Valve
Reversing Valve in Heating Mode
WARNING
HIGH PRESSURE HAZARD
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.
Figure 703 (Checking The Reversing Valve)