Piper SEMINOLE PA-44-180 Information Manual page 221

PA-44-180, SEMINOLE
Safety Switches
Two safety switches activated by the intake valve and located aft of the
heater unit prevent both fan and heater operation when the air intake lever is in
the closed position. A micro switch, which actuates when the landing gear is
retracted, turns off the ventilation blower so that in flight the cabin air is
circulated by ram air pressure only.
Overheat Switch and Annunciator
An overheat switch located in the heater unit acts as a safety device to
render the heater inoperative if a malfunction should occur. Should the switch
deactivate the heater, the red HEATER OVER TEMP annunciator light on the
instrument panel (Figure 7-33) will illuminate. The overheat switch is located
on the aft inboard end of the heater vent jacket. A red reset button is located on
the heater shroud in the nose cone compartment.
To prevent activation of the overheat switch upon normal heater shutdown
during ground operation, turn the three-position switch to FAN for two minutes
with the air intake lever in the open position before turning the switch to OFF.
During flight, leave the air intake lever open for a minimum of fifteen seconds
after turning the switch to OFF.
VENTILATION
When heat is not desired during ground operation, place the three-position
switch in the FAN position and the ventilation fan will blow fresh air through
the heater duct work for cabin ventilation and windshield defogging. To
introduce fresh, unheated air into the cabin during flight, the air intake should
be open and the heater off. Ram air enters the system and can be individually
regulated at each floor outlet.
Overhead outlets also supply fresh air for cabin ventilation. The occupant
of each seat can manually adjust an outlet in the ceiling to regulate the flow of
fresh air to that seat area. A fresh air blower is installed in the overhead
ventilation system to provide additional fresh air flow during ground operation.
Operation of the fresh air blower is controlled by a three-position switch
located on the instrument panel (Figure 7-33) and labeled HIGH-REC BLWR-
LOW.
ISSUED: JULY 12, 1995
SECTION 7
DESCR/OPERATION
REPORT: VB-1616
7-33