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Marvair ComPac AVHDA I&O Manual 03/2019 Rev.3
A comprehensive understanding of the operation of the air conditioner is a prerequisite to troubleshoot-
ing. Please read the Chapter 1 for basic information about the unit.
Our air conditioners are thoroughly tested before they are shipped from the factory. Although unlikely,
it is possible that a defect may escape undetected, or damage may have occurred during transportation.
However, the great majority of problems result from installation errors.
If you experience difficulties with the unit, please review the installation steps in Chapter 2.
Much time can be saved by taking a thoughtful and orderly approach to troubleshooting. Start with a
visual check - are there loose wires, crimped tubing, missing parts, etc? Begin deeper analysis only
after making this initial inspection.
The troubleshooting information in this manual is basic. The troubleshooting section contains problem/
solution charts for general problems, followed by a compressor section.
Not every problem can be anticipated. If you discover a problem that is not covered in this manual, we
would be very grateful if you would bring it to the attention of our service department for incorporation
in future revisions.
As always, please exercise caution and good judgement when servicing the air conditioner. Use only
safe and proven service techniques. Use refrigeration goggles when servicing the refrigeration circuit.
WARNING
The refrigerant circuit has hot surfaces, and the electrical voltages inside of
the unit may be hazardous or lethal. SERVICE MAY BE PERFORMED ONLY BY
QUALIFIED AND EXPERIENCED PERSONS.
4.2 Failure Symptoms Guide
PROBLEM/SYMPTOM
LIKELY CAUSE(S)
CORRECTION
A. Unit does not run.
NOTE: An internal anti-short-cycle
timer will prevent the unit
from starting for .2 to 8
minutes following start-up.
1. Power supply problem.
2. Tripped internal disconnect.
3. Shut off by external thermostat or
thermostat is defective.
4. Unit off on high or low pressure limit.
5. Internal component or connection
failure.
1. Check power supply for adequate phase and voltage.
Check wiring to unit and external breakers or fuses.
2. Check internal circuit protection devices for continuity.
3. Check operation of wall-mounted thermostat.
4. Reset pressure switch.
5. Check for loose wiring. Check components for failure.
B. Unit runs for long periods or continu-
ously; cooling is insufficient.
1. Dirty filter or reduced airflow
2. Low refrigerant.
3. Component failure.
4. Unit undersized for job.
1. Check air filter(s). Check blower operation. Remove
airflow restriction.
2. Check for proper charge and possible refrigerant leak.
3. Check internal components, especially compressor for
proper operation.
4. Add additional units for greater capacity.
