Low Ambient Cooling - Mitsubishi PUZ-A18NHA6 Service Manual

2 Dimensions of flare cutting and flare nut
The component molecules in HFC refrigerant are smaller compared to conventional refrigerants. In addition to that,
R410A is a refrigerant, which has higher risk of leakage because its working pressure is higher than that of other refrig-
erants. Therefore, to enhance air tightness and strength, flare cutting dimension of copper pipe for R410A has been
specified separately from the dimensions for other refrigerants as shown below. The dimension B of flare nut for R410A
also has partly been changed to increase strength as shown below. Set copper pipe correctly referring to copper pipe
flaring dimensions for R410A below. For 1/2 and 5/8 inch pipes, the dimension B changes.
Use torque wrench corresponding to each dimension.
Dimension A
Flare cutting dimensions
Nominal Outside
dimensions (in) diameter (mm)
1/4
3/8
1/2
5/8
3/4
3 Tools for R410A (The following table shows whether conventional tools can be used or not.)
Tools and materials
Gauge manifold
Charge hose
Gas leak detector
Refrigerant recovery equipment
Refrigerant cylinder
Applied oil
Safety charger
Charge valve
Vacuum pump
Flare tool
Bender
Pipe cutter
Welder and nitrogen gas cylinder
Refrigerant charging scale
Vacuum gauge or thermis-
tor vacuum gauge and
vacuum valve
Charging cylinder
: Prepare a new tool. (Use the new tool as the tool exclusive for R410A.)
: Tools for other refrigerants can be used under certain conditions.
: Tools for other refrigerants can be used.

2-4. LOW AMBIENT COOLING

Precautions for low ambient cooling
• If the outdoor temperature is 23°F or lower during cooling operation, install an optional air guide to prevent wind from
blowing into the outdoor unit.
• Install the outdoor unit in a location where wind will not blow onto the back of the unit.
• To prevent damage to the parts, be sure to install the unit, turn on the main power, and perform service in an environment
where the ambient temperature is 0 °F or higher.
• In order to protect the compressor and electrical components, do not turn off the circuit breaker if the unit is installed in an
environment where the ambient temperature is 0°F or lower.
• It needs at least 4hr standby to operation in order to warm the electrical parts.
Note: During cooling operation under low ambient temperature, the bottom fan motor of A42N stops occasionally. This is an
intended feature, not a malfunction.
OCH577A
Dimension A (
(in [mm])
R410A
11/32-23/64 [ 9.1]
6.35
1/2-33/64 [13.2]
9.52
41/64-21/32 [16.6]
12.70
49/64-25/32 [19.7]
15.88
—
19.05
Use
Air purge, refrigerant charge
and operation check
Gas leak check
Collection of refrigerant
Refrigerant charge
Apply to flared section
Prevent compressor malfunction
when charging refrigerant by
spraying liquid refrigerant
Prevent gas from blowing out
when detaching charge hose
Vacuum drying and air
purge
Flaring work of piping
Bend the pipes
Cut the pipes
Weld the pipes
Refrigerant charge
Check the degree of vacuum. (Vacuum
valve prevents back flow of oil and refri-
gerant to thermistor vacuum gauge)
Refrigerant charge
Flare nut dimensions
)
+0
Nominal
-0.4
R22 (mm)
dimensions (in)
9.0 1/4
3/8
13.0
1/2
16.2
5/8
19.4
3/4
23.3
R410A tools Can R22 tools be used?
Tool exclusive for R410A
Tool exclusive for R410A
Tool for HFC refrigerant
Tool exclusive for R410A
Tool exclusive for R410A
Ester oil, ether oil and
alkylbenzene oil(minimum amount)
Tool exclusive for R410A
Tool exclusive for R410A
Tools for other refrigerants can (Usable if equipped
be used if equipped with adop-
ter for reverse flow check
Tools for other refrigerants
(Usable by adjusting
can be used by adjusting
flaring dimension
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other
refrigerants
Tool exclusive for R410A
5
Dimension B
Dimension B
Outside
diameter (mm) (in [mm])
R410A
6.35 43/64 [17.0]
9.52 7/8 [22.0]
12.70 1-3/64 [26.0]
15.88 1-9/64 [29.0]
—
19.05
with adopter for rever-
se flow)
flaring dimension)
(mm)
R22
17.0
22.0
24.0
27.0
36.0