MCC 50-2104 - HVAC Alarm Description 2

2--8
© 2015 Mobile Climate Control
T-367Rev05/2015
2.4.9 HVAC Alarm Description
The MCC Eco Temp NG Controller will notify user
in the event there is a problem or interruption in
system co n t rol. The broadcasted alarms are reported
to the Eco Te mp NG driver display and A/C Fail
Light (if applicable).
a. High or Low pressure Condition
In the event a high pressure or low pressure
condition occurs, the compressor and liquid line
solenoid will be disabled for a minimum of one
minute. High or Low pressure can be triggered by
either a pressure transducer or physical pressure
switch.
1) For high pressure condition, the condenser
and evaporator fan circuits remain energized to bring
the system pressure down. After the one minute
compressor “Off” cycle, if pressures retu rn t o
operational limits, the compressor circuit will
re-energize.
If the high p ressure condition occurs more than
four (4) times within a 20 minute period, the
compressor, LLS and condenser circuits will be
locked out and an alarm will be broadcast to the
Driver display and A/C Fail light.
2) For low pressure condition, the condenser
and evaporator fan circuits remain energized. After
the o n e minute compressor “Off” cycle, if pressures
return to operational limits, the compressor circuit
will re-energize.
If the low pressure conditio n occurs more than
four (4) times within a 20 minute period, the
compressor, LLS and condenser circuit will be
locked out and an alarm will be broadcast to the
Driver display and A/C Fail light.
b. High or Low Transducer Failure
In the event a high pressure or low pressure
transducer fails, the compressor, liquid line solenoid
and co ndenser fans will remain energized, and th e
compressor will unload to two (2) cylinder operation
to allow the system to provide 33% capacity until
condition can be corrected. High and low pressure
switches will disable the cooling circuit in the event
system pressures reach an unsafe condition.
c.SensorFailures
In the event an out of range (Open/Short)
condition occurs with the Return Air, Outside Air,
Deice, or Coil sensors, the system will be unable to
recognize these parameters for proper operation of
A/C system. If one o f these conditions occurs, the
Controller will trigger a code on the display to alert
Driver of this condition.
When alarms occur, the ERROR screen will assist in identifying th e cause of the alarm. Follow instructions in
Section 2.4.7 for instructions for accessing th e ERROR screens.
Alarm Indicator Symbol
Equipment ERRORS 1
Equipment ERRORS 2
Figure 2-7 MCC Eco NG Display Alarms