Allied Air Enterprises 4AC18LT manual Blocking Outdoor Coil

1.Connect the manifold gauge set to the service valve ports as follows (See Figure 13):

•Low pressure gauge to suction line service valve

•High pressure gauge to liquid line service valve

2.Close manifold gauge set valves. Connect the center manifold hose to an upright cylinder of R410A.

3.If room temperature is below 70°F, set the room thermostat to call for heat. This will create the necessary load for properly charging the system in the cooling cycle.

4.Use a digital thermometer to record the outdoor ambient temperature.

5.When the heating demand has been satisfied, switch the thermostat to cooling mode with a set point of 68°F. When pressures have stabilized, use a digital thermometer to record the liquid and suction line temperatures.

6.The outdoor temperature will determine which charging method to use. Proceed with the appropriate charging method.

Charge Using Subcooling Method - Outdoor Temperatures Below 65°F

When the outdoor ambient temperature is below 65°F, the subcooling method can be used to charge the unit. It may be necessary to restrict the air flow through the outdoor coil to achieve pressures in the 200-250 psig range. These higher pressures are necessary for checking the charge. Block equal sections of air intake panels and move obstructions sideways until the liquid pressure is in the 200- 250 psig range (see Figure 11).

1.With the manifold gauge hose on the liquid service port and the unit operating stably, use a digital thermometer to record the liquid line temperature.

2.At the same time, record the liquid line pressure reading.

3.Use the temperature/pressure chart (Table 5 on page

14) to determine the saturation temperature for the liquid line pressure reading.

4.Subtract the liquid line temperature from the saturation temperature (according to the chart) to determine subcooling

Blocking Outdoor Coil

Outdoor coil should be blocked one side at a time with cardboard or plastic sheet until proper testing pressures are reached

CARDBOARD OR

PLASTIC SHEET

Figure 11

Saturation Tempera

_

°Liquid Line Tempera

=° Subcooling Value °F

5.Compare the subcooling value with those shown in Table

6on page 14. If subcooling is greater than shown, recover some refrigerant. If subcooling is less than shown, add some refrigerant.

Charge Using Approach Method - Outdoor Temperatures 65°F or Above

The following procedure is intended as a general guide and is for use on expansion valve systems only. For best results, indoor temperature should be 70°F to 80°F. Monitor system pressures while charging.

1.Record outdoor ambient temperature using a digital thermometer.

2.Attach high pressure gauge set and operate unit for several minutes to allow system pressures to stabilize.

3.Compare stabilized pressures with those provided in Table

8on page 15. Minor variations in these pressures may be expected due to differences in installations. Significant differences could mean that the system is not properly charged or that a problem exists with some component in the system. Pressures higher than those listed indicate that the system is undercharged. Verify adjusted charge using the approach method.

4.Use the same digital thermometer to check liquid line temperature.

5.Subtract the outdoor ambient temperature from the liquid line temperature to determine the approach temperature.

506469-01 Issue 1008 Page 14 of 24