Section 22: HEATING AND AIR CONDITIONING
PA1562
22
compressed refrigerant vapor will be circulated
between the suction and discharge sides of the
head. The affected cylinder head will then have
a relatively even temperature across its surface
and be neither as hot as the normal discharge
temperature nor as cool as the normal suction
temperature.
Blown Head Gaskets
Symptom
:
* Loss of unit capacity at low temperature.
* Even cylinder head temperature.
Cause
:
* Improperly torqued cylinder head bolts.
* Improperly positioned gasket at assembly.
* Warped cylinder head.
* Severe liquid refrigerant floodback.
Blown Valve Plate Gaskets
Symptom
:
* Loss of unit capacity at medium and low
temperatures.
* Very hot cylinder head surface.
* Higher than normal suction pressure.
Cause
:
* Improperly torqued cylinder head bolts.
* Severe liquid refrigerant floodback.
* Oil slugging caused by an overcharge of oil
or flood starts.
* Discharge valves not seated properly (liquid
drainback during shutdown).
Broken Suction Valves
Symptom
:
* Loss of unit capacity at all temperatures.
* Compressor unable to pull extremely low
vacuum with suction service valve
frontseated.
Cause
:
* Repeated liquid refrigerant floodback.
* Flooded starts.
* Overcharge of oil.
* Discharge valves not seated properly (liquid
drainback during shutdown).
* Expansion valve not controlling properly.
Unloader Valve Stuck Open
Symptom
:
* Loss of unit capacity at all temperatures.
* Higher than normal suction pressure.
* Even cylinder head temperature.
Cause
:
* Unloader body stem bent.
* Foreign material binding unloader piston or
plunger.
7.2 MAGNETIC CLUTCH
Refer to Carrier service information entitled
“Housing-Mounted Electric Clutch” at the end of
this section for the description and maintenance
of the magnetic clutch.
7.3 EVAPORATOR MOTOR
The evaporator motor is installed in the
evaporator compartment (L.H. side of vehicle)
(Fig. 25). It is a 27.5 volt, 2 HP (1.5 kW) motor
which activates a double blower fan unit.
FIGURE 25: EVAPORATOR COMPARTMENT 22314
7.3.1 Removal
1. Set the battery master switch (master cut-
out) to the “OFF” position.
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