Section 22: HEATING AND AIR CONDITIONING
PA1553
28
4. Remove the brush holder ring.
5. Finally, separate the following parts: brush
holders, brush boxes, terminal board,
bearings, etc.
9.5 RECEIVER TANK
The receiver tank is located in the condenser
compartment (Fig. 31). The function of the
receiver tank is to store the liquid refrigerant.
During normal operation, the level of the
refrigerant should be approximately at the mid-
point of the lower sight glass.
In case of extreme pressure there will be a rise
in the liquid receiver tank. A pressure relief valve
will break at 450 psi (3103 kPa) and relieve the
receiver tank pressure.
The receiver tank incorporates an inlet valve on
the inlet side (upper section) which allows the
tank to be isolated or serviced. An outlet valve
on the outlet side (lower section) permits
complete isolation from the rest of the system.
FIGURE 31: A/C CONDENSER COMPARTMENT 22243B
9.6 FILTER DRYER
A filter dryer, also located in the condenser
compartment, is installed on the liquid
refrigerant line after the receiver tank. It is used
to absorb moisture and foreign matter from
refrigerant before it reaches the expansion
valves.
The filter should be replaced if the system has
been opened or after a prolonged exposure,
when the moisture indicator sight glass turns to
pink.
9.6.1 Replacement
The filter is of the disposable type. When
replacement is required, remove and discard the
complete unit and replace with a new unit of the
same type according to this procedure:
1. Isolate the refrigerant in the receiver tank by
following the “Pumping Down” procedure
explained in this section
2. Change the filter dryer as a unit.
3. Add a small quantity of refrigerant R-134a to
the low side of the system. Check for leaks.
Return the system to normal operation.
CAUTION
Do not use carbon tetrachloride or similar
solvents to clean parts. Do not use steam
guns. Use mineral spirits or naphtha. All parts
should be thoroughly cleaned. Use a stiff
brush to wash dirt from grooves, holes, etc.
DANGER
Cleaning products are flammable and may
explode under certain conditions. Always
handle in a well ventilated area.
9.6.2 Moisture Indicator
The moisture sensitive element consists of a
color changing ring which is reversible from pink
to blue and vice versa as the moisture content in
the refrigerant changes. Pink indicates a wet
refrigerant, light violet (caution) and blue
indicates a dry refrigerant.
COLOR INDICATOR
TEMPERATURE
BLUE
(ppm)
LIGHT
VIOLET
(ppm)
PINK
(ppm)
75°F (24°C)
100°F (38°C)
125°F (52°C)
Below 5
Below 10
Below 15
5-15
10-30
15-45
Above 15
Above 30
Above 45
p.p.m.= parts per million (moisture content)
Since temperature changes affect the solubility,
color change will also vary with the refrigerant
temperature. The above table shows the color
change for R-134a at various moisture levels
and liquid line refrigerant temperatures.
A moisture level of less than 15 p.p.m. for R-
134a indicated in the blue color range of the
above table is generally considered dry and
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