Chrysler PT Cruiser, Service & Repair Manual, Page: 2017 / 2078

REMOVAL– SERVICE PORT VALVE CORES
(1) Remove the valve caps.
(2) Using a R-134a refrigerant recovery machine,
Remove the refrigerant from A/C system (Refer to 24
- HEATING & AIR CONDITIONING - STANDARD
PROCEDURE).
(3) Using a standard valve core tool, remove the
valve core. Be careful to prevent any dirt/debris
from entering the valve core opening or getting
on the replacement valve core.
INSTALLATION - SERVICE PORT VALVE CORES
(1) When assembling the new valve core into the
port, the core should be oiled with clean ND8 PAG
compressor oil.
CAUTION: A valve that is not fully seated can lead
to damage to the valve during evacuation and
charge. This can result in system refrigerant dis-
charge while uncoupling the charge adapters.
(2) Install valve core into port and tighten.
(3) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING - STANDARD
PROCEDURE).
(4) Recharge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING - STANDARD
PROCEDURE).
(5) Install the valve caps.
A/C VARIABLE ORIFICE TUBE
DESCRIPTION
A Variable Orifice Valve (VOV) is installed in the
liquid line between the outlet of the condenser and
the inlet of the evaporator. The inlet end of the Vari-
able Orifice Valve has a nylon mesh filter screen,
which filters the refrigerant and helps to reduce the
potential for blockage of the metering orifices by
refrigerant system contaminants. The outlet end of
the tube has a nylon mesh diffuser screen. The
O-rings on the plastic body of the VOV seal the tube
to the inside of the liquid line and prevent refriger-
ant from bypassing the metering orifices.
The VOV is only serviced as an integral part of the
liquid line. The VOV cannot be adjusted or repaired
and, if faulty or plugged, the liquid line unit must be
replaced.
REMOVAL - INSTALLATION
The Variable Orifice Valve (VOV) is located in the
liquid line near the condenser. If the VOV is faulty or
plugged, the liquid line unit must be replaced(Refer
to 24 - HEATING & AIR CONDITIONING/PLUMB-
ING/LIQUID LINE - REMOVAL) and (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/
LIQUID LINE - INSTALLATION).
CABIN HEATER
DESCRIPTION
The purpose of the cabin heater is to heat the
engine coolant via resistance heating before it
reaches the heater core. Current from the alternator
is supplied to three glow plug type heating elements
which reside in a single housing in the stream of
coolant flow and as the coolant passes over the ends
of the plugs the heat is transferred to the coolant on
its way to the heater core.
OPERATION
At key on, three temperature sensors record the
ambient air in order to determine if it is cold enough
to turn on the cabin heaters. One sensor is in the
vehicle on the battery under the driver’s seat. The
other two are in the engine compartment (inlet air
temperature and manifold temperature). Based in
the lowest temperature of the three sensors a pre-de-
termined coolant temperature set point is established
at which the cabin heaters will shut off.
For example, if the lowest recorded temperature
from the three sensors is 0° C (32° F) or below, the
heaters will shut off when the coolant temperature
reaches 75° C (167°F). If the lowest ambient air tem-
perature at key on is 10° C (50° F) or higher, then
the heaters will not turn on.
There are three heating elements in the assembly:
Plug 1 = 300W, Plug 2 = 400W and Plug 3 = 300W.
Plug 1 is tied to one relay, while plugs 2 and 3 are
tied to a second relay. Because there are 3 plugs with
only 2 relays, when the cabin heater assembly is
enabled by the engine controller, the firing sequence
is as follows:
•
a) Plug 1 only.
•
b) Plugs 2 and 3 only.
•
c) Plugs 1 to 3.
At each step, the engine controller monitors loads
on the alternator to see if it is OK to proceed to the
next phase of the firing sequence. The system will
back out in the reverse order when a problem is
encountered.
DIAGNOSIS AND TESTING - DIESEL ENGINE
CABIN HEATER
The DRB-III© tester is programmed to allow the
technician to turn each cabin heater relay on and off
at a predetermined number of seconds. During this
point, a voltage drop across each relay can be mea-
sured in order to determine whether they are func-
tioning properly.
PT
HEATING & AIR COND. - RHD 24 - 111
SERVICE PORT VALVE CORE (Continued)