Piper Navajo PA-31 Service Manual page 938

PIPER NAVAJO SERVICE MANUAL
13-40. DISASSEMBLY. (Refer to Figure 13-27, 13-28 or 13-29.)
a. Disassemble the 39D59 heater giving special attention to the following instructions: (Refer to
Figure 13-27 or 13-28.)
1. Remove the screw (56) and slide the elbow adapter (2) off the combustion air inlet tube.
2. Disconnect and remove electrical wiring and individual wires from the various components
on the heater. If wires appear to be in good condition, it may be desirable to remove wire harness assembly
intact. First, disconnect wires at terminal strip and components. The ventilating air blower housing must be
removed so that the two motor wires and solenoid valve quick-disconnect connections may be released.
NOTE
It is advisable to label all wires, prior to removal, to insure correct
connections during reassembly. Cable straps and clips must be
replaced if removed, as they cannot be reused.
3. Carefully disconnect the high-voltage ignition lead at the spark plug. Handle the spring
connector on the end of this lead with care to prevent fouling or damage.
4. Remove the four screws (57), lock washers (58) and cable straps (24) to free the ignition
assembly (3) from the heater jacket and remove the ignition assembly. The vibrator may be removed by
exerting a firm pull straight away from the ignition assembly case.
5. Remove the two screws (59) and lock washers (58) to release the radio-noise filter (6) from
the jacket (17).
6. Remove the grommet (21) from the jacket (17) and remove the spark plug (5) with a 7/8
inch deep socket. Make sure the spark plug gasket is removed.
7. Remove the two screws (61), lock washers (58) and plain washers (65) and lift out the
overheat (limit) switch (7) and spacer gaskets (8).
8. Remove the two screws (61), lock washers (43) and plain washers (65) and lift out the
cycling switch (9).
9. Remove the four screws (64) and lock washers (58) to release the terminal strip (10) and
insulator (25) from the jacket (17).
10. Disconnect the tube elbow fitting (11) at the cover of the combustion air pressure switch
(12). (Refer to Paragraph 13-36, Step a, No. 1, for precaution on tube bending.) Unscrew and remove the
combustion air pressure switch (12) from the combustion air inlet tube.
11. Loosen the four fasteners (28) and rotate the blower and motor housing (39) to disengage
the notched end from the four screws in the end of the heater jacket. Remove the grommet (27) and
separate the two electrical quick-disconnects after sliding back the insulator sleeves on the wire ends.
12. Reach inside the inlet end of the jacket assembly (17) with a 3/4 inch open-end wrench and,
while holding the fuel-tube fitting at the jacket, remove the reducing bushing adapter (13). Then, with 3/4
inch deep socket, remove the nut (60), fuel fitting shroud (14) and gasket (26).
13. Remove the two screws (61) and lock washers (62) and carefully withdraw the nozzle
holder and valve assembly from the combustion tube assembly (19). Remove the gasket (15).
14. Remove the screws (63), lock washers (43) and remaining cable straps (24), if not previously
removed, from the seam of the jacket assembly (17). Note positions of cable straps as they are removed.
Spread the jacket (17) at the seam and remove it from the combustion tube assembly (19). This will free
the rope gasket (18) which can be removed from the particular part on which it remains attached.
15. Carefully unscrew and remove the spray nozzle (16) from the nozzle holder and solenoid
valve assembly.
Reissued: 10/12/79
Reissued: 10/12/79
HEATING AND VENTILATING SYSTEM
5C8