238 Auto Heating & Air Conditioning
Defective Accumulator/Receiver-Drier
Usually, accumulators and receiver-driers are not the
source of air conditioning system problems. However, they
can cause other system problems, such as restrictions in the
orifi ce tube or expansion valve should the desiccant bag
rupture. On accumulators and driers with an oil bleed hole,
compressor failure can be caused if this hole is restricted. A
problem in an accumulator will usually show up as another
problem in the system, and cannot be detected by gauge
readings.
Figure 15-15. Gauge pressures indicating a restriction in the line, orifi ce tube, or expansion valve. Do
not allow a restricted system to run for an extended period of time as high pressures may cause a
hose or line to burst.
Restriction in Line, Orifice Tube, or Expansion Valve
Low Side (Suction)
Symptoms: Poor or no coolling, compressor cycles frequently, system pressure equalizes
slower than normal when system is turned off (orifice tube systems). Sight glass clear, blown
thermal limiter (when used). High pressure lines have frost on them.
Orifice Tube
Exp. Valve
VDOT
(Varies with ambient temperature) (Varies with ambient temperature)
Normal to Vacuum
Low
Very Low to Vacuum
High to Low
Low
Low
High Side (Discharge)
0
10
20
30
4
0
50
60
70
80
90
100
110
120
0
5
0
100
150
200
250
300
350
400
450
500
Figure 15-14. Gauge pressures for a system overcharge condition.
Refrigeration System Overcharged
Low Side (Suction)
Symptoms: Fair to poor cooling, continuous compressor operation (orifice tube systems),
sight glass clear or foamy.
Orifice Tube
Exp. Valve
VDOT
(Varies with ambient temperature) (Varies with ambient temperature)
High
Normal to High
Normal to High
High
High
High
High Side (Discharge)
0
10
20
30
40
50
60
70
80
9
0
100
110
120
0
50
100
15
0
200
250
300
350
400
450
500