Section 6
Service
6-7
HOT GAS VALVE TEMPERATURE CHECK
Function
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 Check
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.
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.
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.
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
Comments
The inlet of the
hot gas valve is
cool enough to
touch and the
compressor
discharge line is
hot.
This is normal as the discharge
line should always be too hot to
touch and the hot gas valve
inlet, although too hot to touch
during harvest, should be cool
enough to touch after 5 minutes
into the freeze cycle.
The inlet of the
hot gas valve is
hot and
approaches the
temperature of a
hot compressor
discharge line.
This is an indication something
is wrong, as the hot gas valve
inlet did not cool down during
the freeze cycle. If the
compressor dome is also
entirely hot, the problem is not
a hot gas valve leaking, but
rather something causing the
compressor (and the entire ice
machine) to get hot.
Both the inlet of
the hot gas valve
and the
compressor
discharge line
are cool enough
to touch.
This is an indication something
is wrong, causing the
compressor discharge line to be
cool to the touch. This is not
caused by a hot gas valve
leaking.
