Performance Test Of The Air Conditioning System; Performance Test In Cold Climates - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
14-91. PERFORMANCE
TEST. A performance test of the system is the only positive way in which the
complete system can be checked for efficient operation. The air conditioning system should be given this test
before work is begun on the system whenever possible, however, if the system is completely inoperative. repairs
must be performed before the system can be properly tested. The test can uncover further work that must be
performed before the system is brought to its full operating efficiency. The performance test should always be
performed after repair work has been done and before the aircraft is released to the customer. The serviceman
performing this test carefully will insure that the repairs have been properly performed and that the system will
operate satisfactorily.
The performance test when properly performed includes a thorough examination of the outside of the
system as well as the inside. Many related parts are overlooked because it is felt they are of no bearing on
the operating efficiency of the unit. For this reason, a thorough visual inspection of the complete system
should be performed, followed by an operating inspection of the system.
14-92. PERFORMANCE
TEST IN COLD CLIMATES. To run a performance test on the PA-31-350 air
conditioning in cold climates, below 70
°
F, the following procedures will have to be used:
a. Obtain an air blower with the following requirements:
I. 300 cfm at 3.0" H20 static pressure with standard air density of .0765 Ibs/cu ft.. or a Piper
recirculating air blower from the PA-3 IP, Piper Part No. 460 003.
b. Take the air blower and connect the exhaust side to an appropriate hose.
c. Insert the hose into the PA-31-350 nose inlet opening. Using the PA-31-350 heater with the air
blower, the necessary cabin heat load will be supplied.
CAUTION
Since the nose inlet opening on the PA-31-350 is on the lower
right-hand side of the nose, and the air conditioning unit operates
off the right engine, be sure the air blower and hose are secure,
and all personnel clear.
d. Start the air conditioning for the performance test.
e. With the heater and air blower operating, the air conditioner should be allowed to operate until
the freeze protection shuts it down.
f.
With the freeze protection checked, remove the spar splice access plate.
g. Place a jumper wire (No. 18 or larger) across the freeze protection pressure switch, wires H115EE
and H95EF.
h.
This will allow further operation to check the thermostat operation and the freon level.
Reissued: 9/23/80
4 G17
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