Friedrich WallMaster WCVT12B30A handleiding

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Handleiding

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A reversing valve is a component of a heat pump that changes the direction of

refrigerant ﬂow, allowing the system to function in both heating and cooling

modes.

It consists of a pressure-operated, main valve and a pilot valve actuated

by a solenoid plunger. The solenoid is energized by 24 vac during the

heating cycle only.

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 plunger 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.

Checking the Reversing Valve

NOTE: System operating pressures must be near normal before valve

can shift.

NOTE: You must have normal operating pressures

before the reversing valve can shift.

Run the unit in the heating mode then disconnect one of the 24

vac wires at the reversing valve and the valve should shift to

cooling mode. If valve does not shift - replace the valve(verify the

unit is properly charged before replacing valve.) For a stuck valve

diagnosis run in the cooling mode and check the temp difference

between the suction line from the evaporator and the common

suction line at the compressor, if there is more than a 3 ˚F

difference then change the valve.

Checking The Reversing Valve Solenoid

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 resistance through the coil. If the coil is

open 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.

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.

COMPONENT TESTING

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.

WARNING

ELECTRIC SHOCK HAZARD

Disconnect power to the unit before

servicing. Failure to follow this warning

could result in serious injury or death.

Figure 701

Figure 702

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