Lennox International Inc Comprehensive Guide to Lennox Merit Series Air Conditioners

	USE WEIGH-IN METHOD								65ºF (18.3ºC)		1.	Confirm proper airflow across coil using figure 19.
									and above		2. Compare		unit pressures with table		4, Normal
Weigh-in or remove refrigerant												Operating Pressures.
based upon line length
											3.	Set thermostat to call for heat (must have a cooling load
									ABOVE or			between 70-80ºF (21−26ºC)
						64ºF (17.7ºC)					4.	Connect gauge set
									BELOW
						and below					5.	Measure outdoor ambient temperature
					BLOCK OUTDOOR COIL: [sometimes necessary with lower						6.	When heat demand is satisfied, set thermostat to call for
												cooling
					temperatures] Use cardboard or plastic sheet to restrict the
											7.	Allow temperatures and pressures to stabilize.
					airflow through the outdoor coil to achieve pressures from
					325−375 psig (2240−2585 kPa). Higher pressures are needed							NOTE − If necessary, block outdoor coil to maintain 325
					to check charge. Block equal sections of air intake panels and							− 375 psig.
	CARDBOARD OR				move coverings sideways until the liquid pressure is in the						8.	Record liquid line temperature:
					above noted ranges.
												LIQº = ______
		PLASTIC SHEET
											9.	Measure liquid line pressure and use the value to
	If refrigerant is added or						If value is MORE than shown,
												determine saturation temperature (see table 3):
	removed, verify charge using						remove refrigerant.
	the Approach Method.											SATº = ______
											10.	Subtract to determine subcooling (SCº):
												SATº_____ − LIQº _____ = SCº _____
			If value is LESS			MORE or
											11.	Compare results with table below.
			than shown, add
							LESS
			refrigerant.
								SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
ºF (ºC)*				−018	−024			−030	−036	−041	−042		−047	−048	−059/−060
65 (18)				10 (5.6)	10 (5.6)			11 (6.1)	13 (7.2)	9 (5.0)	10 (5.6)		6 (3.3)	8 (4.4)	8 (4.4)
75 (24)				6 (3.3)	7 (3.9)			8 (4.4)	9 (5.0)	7 (3.9)	7 (3.9)		6 (3.3)	8 (4.4)	7 (3.9)
85 (29)				6 (3.3)	8 (4.4)			6 (3.3)	7 (3.9)	7 (3.9)	8 (4.4)		6 (3.3)	8 (4.4)	8 (4.4)
95 (35)				6 (3.3)	9 (5.0)			6 (3.3)	8 (4.4)	7 (3.9)	8 (4.4)		6 (3.3)	8 (4.4)	7 (3.9)
105 (41)				10 (5.6)	9 (5.0)			7 (3.9)	9 (5.0)	7 (3.9)	8 (4.4)		6 (3.3)	8 (4.4)	6 (3.3)
115 (45)				10 (5.6)	10 (5.6)			8 (4.4)	10 (5.6)	6 (3.3)	7 (3.9)		5 (2.8)	7 (3.9)	6 (3.3)

*Temperature of air entering outdoor coil.

Figure 23. HFC−410A Subcooling TXV Charge

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14ACX SERIES