Manitowoc QF0800 Spezifikationen PDF herunterladen (Seite 199)

Part Number 80-1230-9 6/08 199

Head Pressure Control Valve

Manitowoc remote systems require head pressure

control valves with special settings. Replace defective

head pressure control valves only with “original”

Manitowoc replacement parts.

OPERATION

The R404A head pressure control valve is non

adjustable.

At ambient temperatures of approximately 70°F (21°C)

or above, refrigerant flows through the valve from the

condenser to the receiver inlet. At temperatures below

this (or at higher temperatures if it is raining), the head

pressure control dome’s nitrogen charge closes the

condenser port and opens the bypass port from the

compressor discharge line.

In this modulating mode, the valve maintains minimum

head pressure by building up liquid in the condenser

and bypassing discharge gas directly to the receiver.

DIAGNOSING

1. Determine if the coil is clean. Air passes through

the condenser from the bottom up. Verify the coil

is clean by looking from the bottom up. Do not

look down through the fan.

2. Determine the air temperature entering the

remote condenser.

3. Determine if the head pressure is high or low in

relationship to the outside temperature. (Refer to

the proper “Cycle Times/24-Hour Ice Production/

Refrigerant Pressure Charts”).

4. Determine the temperature of the liquid line

entering the receiver by feeling it. This line is

normally warm; “body temperature.”

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Manitowoc QF0800 Spezifikationen Seite 199