Aaon HVAC Unit RN-040-3-0-BQ

Temperature and Pressure Measurement

Measure the temperature of the liquid line as it leaves the condenser coil

Read the gauge pressure at the liquid line close to the point where the temperature was taken

Pressure Conversion and Calculation

Convert the pressure obtained to a saturated temperature using the appropriate refrigerant temperature-pressure chart

Subtract the measured liquid line temperature from the saturated temperature to determine the liquid sub-cooling

Compare calculated sub-cooling to the table below for the appropriate unit type and options

Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

Check the gas pipe in the unit for leaks before startup.

Disconnect all wiring on the heat exchanger.

Disconnect flex gas lines and pull out of the way.

Remove screws around the perimeter of the heat exchanger face plate that connect it to the unit. Only the outermost screws should be removed.

Pull the heat exchanger straight back and out of the unit.

Was it necessary to remove some of the control door jambs?

Ensure all necessary equipment and materials are available

Pump the cleaning liquid through the exchanger

Ensure cleaning solution flow rate is a minimum of 1.5 times the normal flow rate

Rinse the heat exchanger with clean water

Use a solution of 1-2% sodium hydroxide (NaOH) or sodium bicarbonate (NaHCO) before the last rinse

Is the fan at normal operating temperature?

Select the grease used for lubrication

Add grease to purge the seals (grams)

Was the lubrication process completed without over-lubricating?

Ensure the furnace is turned off

Verify that the gas supply is shut off

Flue Product Carrying Areas Inspection

Inspect flue product carrying areas for blockages or damage

Are all flue product carrying areas in good condition?

Inspect main burners for signs of wear or damage