Hot Gas Valve Temperature Check - Manitowoc Marine Q 1800 Service Manual

HOT GAS VALVE TEMPERATURE CHECK

General
A hot gas 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.
Normally, a defective hot gas valve can be rebuilt.
Refer to the Parts Manual for proper valve
application and rebuild kits. If replacement is
necessary, Use only "original" Manitowoc
replacement parts.
Hot Gas Valve Analysis
Symptoms of a hot gas 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
hot gas valve is by using Manitowoc's Ice Machine
Refrigeration System Operational Analysis Table.
Use the following procedure and table to help
determine if a hot gas valve is remaining partially
open during the freeze cycle.
1. Wait five minutes into the freeze cycle.
2. Feel the inlet of the hot gas valve(s).
Important
Feeling the hot gas valve outlet or across the hot
gas valve itself will not work for this comparison.
The hot gas valve outlet is on the suction side
(cool refrigerant). It may be cool enough to touch
even if the valve is leaking.
Refrigeration System
3. Feel the compressor discharge line.
WARNING
The inlet of the hot gas 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 hot
gas valves to the temperature of the compressor
discharge line.
Findings
The inlet of the This is normal as the discharge
hot gas valve is line should always be too hot to
cool enough to touch and the hot gas valve
touch and the inlet, although too hot to touch
compressor during harvest, should be cool
discharge line is enough to touch after 5
hot. minutes into the freeze cycle.
The inlet of the This is an indication something is
hot gas valve is wrong, as the hot gas valve
hot and inlet did not cool down during
approaches the the freeze cycle. If the
temperature of compressor dome is also
a hot entirely hot, the problem is not
compressor a hot gas valve leaking, but
discharge line. rather something causing the
compressor (and the entire ice
machine) to get hot.
Both the inlet of This is an indication something is
the hot gas wrong, causing the compressor
valve and the discharge line to be cool to the
compressor touch. This is not caused by a
discharge line hot gas valve leaking.
are cool enough
to touch.
Comments
37