Manitowoc Ice S1800 service manual Harvest Valve Temperature Check General, Harvest Valve Analysis

Section 7 Refrigeration System

HARVEST VALVE TEMPERATURE CHECK General

NOTE: This procedure requires checking both harvest valves.

A harvest valve requires a critical orifice size. This meters the amount of hot gas flowing into the evaporator during the harvest cycle. If the orifice is even slightly too large or too small, long harvest cycles will result.

A too-large orifice causes refrigerant to condense to liquid in the evaporator during the harvest cycle. This liquid will cause compressor damage. A too-small orifice does not allow enough hot gas into the evaporator. This causes low suction pressure, and insufficient heat for a harvest cycle.

Refer to the Parts Manual for proper valve application. If replacement is necessary, Use only “original” Manitowoc replacement parts.

Harvest Valve Analysis

Symptoms of a harvest valve remaining partially open during the freeze cycle can be similar to symptoms of either an expansion valve or compressor problem. The best way to diagnose a harvest valve is by using Manitowoc’s Ice Machine Refrigeration System Operational Analysis Table.

Use the following procedure and table to help determine if a harvest valve is remaining partially open during the freeze cycle.

1.Wait five minutes into the freeze cycle.

2.Feel the inlet of the harvest valve(s).

Important

Feeling the harvest valve outlet or across the harvest valve itself will not work for this comparison.

The harvest valve outlet is on the suction side (cool refrigerant). It may be cool enough to touch even if the valve is leaking.

3. Feel the compressor discharge line.

!Warning

The inlet of the harvest valve and the compressor discharge line could be hot enough to burn your hand. Just touch them momentarily.

4.Compare the temperature of the inlet of the harvest valves to the temperature of the compressor discharge line.

Findings	Comments
The inlet of the	This is normal as the discharge line
harvest valve is cool	should always be too hot to touch and
enough to touch and	the harvest valve inlet, although too
the compressor	hot to touch during harvest, should be
discharge line is hot.	cool enough to touch after 5 minutes
	into the freeze cycle.
The inlet of the	This is an indication something is
harvest valve is hot	wrong, as the harvest valve inlet did
and approaches the	not cool down during the freeze cycle.
temperature of a hot	If the compressor dome is also entirely
compressor	hot, the problem is not a harvest valve
discharge line.	leaking, but rather something causing
	the compressor (and the entire ice
	machine) to get hot.
Both the inlet of the	This is an indication something is
harvest valve and	wrong, causing the compressor
the compressor	discharge line to be cool to the touch.
discharge line are	This is not caused by a harvest valve
cool enough to	leaking.
touch.

Part Number 80-1634-3 7-15