- 1. The outdoor unit should be level.
This is important for proper distribution of oil for lubricating the compressor as well as for
- 2. The outdoor unit should have a pad under it that is made of hardened plastic or concrete.
This is to provide a solid base for the unit.
- 3. The outdoor unit should be about 1 foot away from the house.
This is to allow proper air circulation through the condensing unit. Without proper airflow, the unit
will have higher operating pressures which will use more electricity and also cause more wear and tear
on the unit.
- 4. There should be a refrigerant filter/drier in the system.
This will look like a metal can surrounding the smaller refrigerant line. If you do not see one on the
lines outside the unit, look on the inside of the unit as many brands now include them from the factory.
This is important to ensure that there is no moisture inside the refrigerant system. Moisture, when
combined with refrigerant and elevated temperatures can produce an acid. This acid can cause leaks in
the system over time and costly repairs.
- 5. There should be an electrical disconnect within 3 feet of the outdoor unit.
This is an important safety requirement for repairs, maintenance, and emergency situations. It is
required by most residential and commercial building codes.
- 6. There should not be any scraps or trash from the installation left laying around.
Someone that does not pay attention to the small things is likely to perform a sub-standard air
- 7. The large copper line running from the outdoor unit to the indoor unit should be insulated and
there should not be any tears in the foam insulation.
This is important for maintaining efficiency as well as for proper compressor operation.
- 8. The copper lines should be supported about every 4 feet. Ensure that there are no sagging places
in the lines.
A sagging line can trap oil that is needed to lubricate the compressor. If the compressor does not
have sufficient oil, it will fail.
- 9. The copper lines should be as short as possible.
- 10. Normally the copper lines should be the same size as the connections on the unit.
If not, ask why and ensure you understand the reason.
- 11. Both the main and emergency drain connections on the indoor coil should be connected to a
- 12. Run the system through a complete cooling cycle to ensure it works properly.
During this time, it is a good idea to check the temperature drop across the evaporator coil. This is
done by measuring the temperature of the air in the main supply duct and subtracting it from the
temperature of the air entering the furnace/air handler. (On a modern high efficiency unit, this should
be around 12 to 14 degrees)