There are a few different types of AC noise that can be caused by many different things. This document focuses on what is most common, which is –
“LINE SET NOISE INDOORS CAUSED BY VIBRATION FROM THE COMPRESSOR”.
This tech tip focuses specifically on the situation where there is NOT excess noise outside and the indoor noise is usually along the first 10 feet after the lines enter the house. It usually sounds like the typical “compressor noise” that you hear from an AC condenser or refrigerator.
Compressor manufacturers tell us that this is happening because there is not enough equivalent distance between the compressor and the house for the noise/vibration to dissipate. We all know that a longer lineset run before entering the house is not always practical, so here are some steps to take to prevent or reduce AC noise on the line set. It starts with the installation……
- Make sure line set is not touching the sides of the entry hole to the house
- If the outdoor unit is below the indoor coil, make certain the suction line extends above the coil before returning to the outdoor unit. (includes upflow units in closets)
- Make sure the line set is not tightly strapped to the building joists
- Make sure unit is not overcharged and outdoor coil is clean
- Verify “proper” airflow – “Yes it makes a difference”
- Loosen compressor bolts – Loosen ¼ to ½ turn max
- Install Mass Damper Kit. Part number: 328209-751 (suction) and 308421-202 (liquid)
- Alter the suction line installation at the outdoor unit.
- Install A-C Renew in the system and allow the system to operate for two weeks.
a. Tech support will concession labor and materials for this.
Install an “inverted trap” in the suction line as shown as found in the Application Guideline and Service Manual for Residential Air Conditioners and Heat Pumps Using R-22 and Puron Refrigerant.
Install or bend two 90-degree elbows before entering the house.
Using a ratcheting tubing bender, making two 90-degree bends before entering the building can be cheap insurance that you will not run into an AC compressor noise that requires cutting into the system, and it reduces braze joints and possible leaks.
Suggested step by step process:
- Run the line set out of the hole
- Make the first 90-degree bend running the piping close parallel to the wall
- Set the pad for the condenser
- Make your second 90 degree bend perpendicular to the wall at the edge of the
condenser pad (On the service valve side of the condensing unit) - Set the condensing unit and mark the location of the 45-degree final bend
- Slide the unit from the pad and make the final bend and cut