Multi-Zone Technical Overview

ERROR CODES
PAGE 31
ENGLISH
Outdoor Unit Pressure Switch Error Codes
There are two pressure switches in the outdoor unit, a low pressure switch and a high pressure switch. They connect to the
ECU via plugs CN-12 and CN-13. The low pressure switch is connected at CN-12 and the high pressure switch at CN-13. A low
pressure error will generate an Error Code 44. A high pressure error will generate an Error Code 45.
Testing Procedure
If the system generates one of these codes, it is very unlikely that the switch is actually bad, it is much more likely that the
refrigeration system pressures are either too high or too low. The vapor line connection can be used to measure the high pres-
sure during heating mode operation and low pressure during cooling mode operation.
There are no pressure ports that can be accessed to measure low pressure in heat mode nor high pressure in cool mode. If the
system trips on one of these errors where pressure cannot be measured, it is going to be necessary to remove system charge
and re-charge to conrm low or high charge is not causing the problem.
Low
Pressure
Switch
High
Pressure
Switch
Error Code 43 or 45
This code is indicating that system pressure is too low. Refer
to the detailed information on sensor responses for more
information.
Typical Causes of Low Pressure Cool Mode
• Lack of charge (hot compressor)
• Low Heat on Indoor Coil (Cool Compressor)
• Restriction (Not likely)
Typical Causes of Low Pressure Heat Mode
• Cold outdoor air (Running system in very cold air.)
• Lack of charge (Hot Compressor and Indoor Coil)
• Restriction (Not Likely)
Error Code 42 or 44
The system is operating at excessive refrigerant pressure. If
the system is a new installation, it is likely that the charge is
too high. Refer to the reference section for installation and
charging procedure. (Note the Weight Method is the ONLY
way to charge this system. )
Typical Causes of High Pressure In Cool Mode
• Overcharge
• Dirty Outdoor Coil
• Restriction (Not Likely)
Typical Causes of High Pressure In Heat Mode
• Overcharge
• Undersized Refrigerant Lines/Exceeding Length
• Restriction (Not Likely)
Note: If the refrigerant pressures are correct, yet the system
does not close the error reporting pressure switch, replace
the defective pressure switch.
OUTDOOR UNIT ERROR CODES
Pressure Switch Error Codes