Piper Navajo PA-31 Service Manual page 923

PIPER NAVAJO SERVICE MANUAL
13-20. INSTALLATION OF HEATER.
a. Position the heater on its mounting bracket and secure with clamp.
b. Attach the forward end of the heater to the fuselage bulkhead.
c. Connect the air inlet hose to the forward end of the heater.
d. Connect the fuel line and install shroud cover.
e. Connect the fuel drain to the underside of the heater.
f. Position the combustion air blower, connect tubes and secure the unit to its mounting bracket.
g. Connect the defroster and heat ducts to the air-heat distribution box.
h. Connect the heat control cable to the control arm located on the air-heat distribution box.
Adjust the cable so that when the door is completely closed, approximately .062 to .125 inch springback
exists between the control lever and lever stop.
i. Connect the duct switch control cable to the switch on the right side of the air-heat distribution
box. Adjust the cable so that when the control lever is full against its stop the control arm aligns with the
vertical line of the switch. (Do not loosen the alien set screw that secures the arm to the switch shaft.) Move
the lever to the extreme right to ascertain that the control arm on the duct switch will have a 105
°
± 1
travel to high heat position.
j. Connect the electrical leads to the heater. (A wiring schematic of the heater hook-up may be
found in the Electrical System Diagram, Section XI.)
k. Operate the heater long enough to determine that the unit is operating properly.
1. Install the access panels in the baggage compartment and at the side of the fuselage.
13-21. HEATER ELECTRICAL SYSTEM CHECKS.
13-22. ELECTRICAL CONTINUITY CHECK. These tests are listed as an aid in isolating open circuited or
inoperative components.
NOTE
The schematic wiring diagrams (refer to Figures 13-10 through
13-18) show, in addition to the heater circuitry, a suggested
aircraft control circuit. For the purposes of this manual, the
circuitry shown in these illustrations will be utilized to describe
electrical continuity checks.
It must be assumed that power, which is furnished through the heater circuit breaker, is present at the
HEATER SWITCH at all times. Always check the circuit breaker before performing electrical continuity
checks.
13-23. VENT BLOWER POWER CIRCUIT CHECK.
a. With the HEATER SWITCH in the FAN position, electrical continuity (24-volts nominal) should
be present at the following locations: (Refer to Figures 13-13, 13-14 or 13-15.)
1. Terminal No. 6 on the heater terminal strip.
2. From terminal No. 6 of the heater terminal strip through the radio noise filter to the
ventilating air motor.
3. Electrical ground circuit for the ventilating air motor is provided from terminal No. 4 of the
heater terminal strip through the LANDING GEAR SWITCH when the landing gear is down. Ventilating air
motor is inoperative when the landing gear is up.
Reissued: 10/12/79
5B17
HEATING AND VENTILATING SYSTEM
5B 17