Section 22: HEATING AND AIR CONDITIONING
PA1593
29
Example of readings taken at fig. 35:
A/C pressure gauge
converted to
temperature at
expansion valve fitting
Temperature on
remote bulb
40°F (4,4°C)
Low-
swing
44°F
(6,6°C)
High
swing
54°F
(12,2°C)
Formula for superheat
49°F-40°F=9°F
(9,4°C-4,4°C = 5°C)
Average of low and
high swing is 49°F
(9,4°C)
NOTE
The low swing of the superheat should be a
minimum of 4°F (2,2°C) higher at the remote
bulb and have an average of 8 to 12°F (4 to
6°C) higher range at the bulb than the fitting at
the expansion valve.
NOTE
To reduce the superheat, flow of refrigerant is
increased by turning adjusting screw of
expansion valve lower evaporator temperature
counterclockwise. To increase temperature or
increase superheat, flow of refrigerant is
reduced by turning adjustment screw of
expansion valve clockwise
.
6. Regulate suction pressure to temperature
reading according to temperature chart or to
the R-134a temperature scale on the
pressure gauge.
Example:
Suction pressure 30 psi (207 kPa)
converted to 32
o
F (0
o
C) on chart. If temperature
reading is 40
o
F (4,4
o
C), subtract 32
o
F (0
o
C) and
the result will be 8
o
F (4,4
o
C) of superheat.
CAUTION
Before proceeding to the expansion valve
adjustment, check for restriction on suction
side for plugged filter dryer and partially open
valves. These conditions will give a high
superheat.
Maintenance
1. Pump down the system as previously
indicated in this section.
2. Disconnect the external equalizer line from
the under side of the power head, and
unclamp the remote control bulb from the
evaporator coil outlet line.
3. Remove the two cap screws holding the
power assembly to the valve body flange.
Lift off the power assembly and remove the
cage assembly.
4. When reassembling, replace with the new
gaskets in proper location. Make sure the
two lugs on the cage assembly fit into
grooves provided in the power assembly.
Do not force the valves together. The cage
must fit properly before tightening the body
flange. Tighten bolts evenly.
5. Check for leaks.
Safety Instructions
1. Make sure the valve is installed with the
flow arrow on the valve body corresponding
to the flow direction through the piping
system.
2. Before opening any system, make sure the
pressure in the system is brought to and
remains at the atmospheric pressure.
Failure to comply may result in system
damage and/or personal injury.
7.8.2 Driver’s HVAC Unit
The function and operation of the expansion
valve for the driver’s HVAC unit are similar to the
passenger’s HVAC unit but no superheat
adjustment is required (see figures 19 and 33).
7.9 TORCH
BRAZING
Use electrode containing 35% silver.
CAUTION
When using heat near a valve, wrap with
water saturated rag to prevent overheating of
vital parts.
DANGER
Before welding any part of refrigeration
system, make sure the area is well ventilated.
Summary of Contents for X3-45 2016
Page 4: ......
Page 16: ...Section 00 GENERAL INFORMATION PA1593 12 FIGURE 12 METRIC US STANDARD CONVERSION TABLE 00005...
Page 17: ...Section 00 GENERAL INFORMATION 13 PA1593 FIGURE 13 CONVERSION CHART 00006...
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Page 72: ...Section 04 EXHAUST AND AFTERTREATMENT SYSTEM PA1593 14 7 TORQUE SPECIFICATIONS...
Page 73: ...SECTION 04 EXHAUST AND AFTERTREATMENT SYSTEM PA1593 15...
Page 74: ...Section 04 EXHAUST AND AFTERTREATMENT SYSTEM PA1593 16...
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Page 176: ...SECTION 06B ELECTRICAL 38 overcurrent working Circuit 306 shorted to ground...
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Page 205: ...Section 09 PROPELLER SHAFT PA1593 3 FIGURE 1 PROPELLER SHAFT ASSEMBLY 09002...
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Page 295: ...SECTION 16 SUSPENSION PA1593 9 2 5 TORQUE SPECIFICATIONS...
Page 296: ...Section 16 SUSPENSION PA1593 10...
Page 297: ...Section 16 SUSPENSION PA1593 11...
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Page 413: ...Section 22 HEATING AND AIR CONDITIONING PA1593 15 FIGURE 18 REFRIGERANT CIRCUIT CENTRAL SYSTEM...
Page 433: ...Section 22 HEATING AND AIR CONDITIONING PA1593 35 FIGURE 36 CENTRAL HEATING SYSTEM COMPONENTS...