Goodman Mfg CONDENSING AC UNIT SINGLE / THREE PHASE AIR CONDITIONERS Troubleshooting, Ft-lbs

For the 7-1/2 ton unit starting charge should be 15 lb of R-22 and 18 lbs for the 10 ton unit. The length of line set, indoor unit airflow, condensing unit location and number of tubing fittings will have an impact on final unit charge amount. Turn the elec- trical power on, and let the system run. Wait for the refrigerant pressures to stabilize.

Charge Verification

WARNING

REFRIGERANT UNDER PRESSURE!

•Do not overcharge system with refrigerant.

•Do not operate unit in a vacuum or at negative pres-

sure.

Failure to follow proper procedures may cause property damage, personal injury or death.

CAUTION

Use refrigerant certified to AHRI standards. Use of used refrigerant may cause compressor damage that is not covered under warranty. Most portable machines cannot clean used refrigerant to meet AHRI standards.

NOTICE

Violation of EPA regulations may result in fines or other penalties.

CAUTION

Operating the compressor with the suction valve closed may cause serious compressor damage.

Final Charge Adjustment

The outdoor temperature must be 60°F or higher. Set the room thermostat to COOL, fan switch to AUTO, and set the tem- perature control well below room temperature.

After system has stabilized per startup instructions, check subcooling and superheat as detailed in the following section.

Expansion Valve System

1.Purge gauge lines. Connect service gauge manifold tobase-valve service ports. Run system at least 10 min- utes to allow pressure to stabilize.

2.Temporarily install thermometer on liquid (small) line near liquid line service valve with adequate contact and insu- late for best possible reading.

3.Check subcooling and superheat. Systems with TXV ap- plication should have a subcooling of 11 ± 2 ºF and su- perheat of 9 ± 1 ºF.

a.If subcooling and superheat are low, adjust TXV to 9 ± 1 ºF superheat, then check subcooling.

NOTE: To adjust superheat, turn the valve stem clock- wise to increase and counter clockwise to decrease.

b.If subcooling is low and superheat is high, add charge to raise subcooling to 11 ± 2ºF then check superheat.

c.If subcooling and superheat are high, adjust TXV valve to 9 ± 1 ºF superheat, then check subcooling.

d.If subcooling is high and superheat is low, adjust TXV valve to 9 ± 1 ºF superheat and remove charge to lower the subcooling to 11 ± 2ºF.

NOTE: Do NOT adjust the charge based on suction pres- sure unless there is a gross undercharge.

4.Disconnect manifold set, installation is complete. Subcooling Formula = Sat. Liquid Temp. - Liquid Line Temp.

NOTE: Check the Schrader ports for leaks and tighten valve cores if necessary. Install caps finger-tight.

NOTE: Subsequent opening and replace of the cap will require only 1/2 to 1 hex flat. See the table below for the torque required for an effective seal on the valve bonnet (1/6 turn past finger tight.

TUBING SIZE	TORQUE
	(ft-lbs)
5/8	14
1 3/8	16

After closing the valve bonnet, perform a final refrigerant leak test on the valves and sweat connections. Return the room thermostat to the desired settings.

Troubleshooting

Qualified Installer/Servicer Only

When troubleshooting, the first step should always be to check for clean coils, clean filter(s), and proper airflow. Indoor airflow should be 375 to 425 CFM per ton of cooling based on the size of the outdoor unit. The most common way of establishing indoor airflow is heating temperature rise. Indoor airflow will then be (Heating output of equipment) / (1.1 x temp. rise). In other cases, measurement of external static pressure is help- ful. For details, see the Installation Instructions for your indoor unit.

7