Mooney M20V - Page 151

MOONEY INTERNATIONAL CORPORATION
M20V SERVICE AND MAINTENANCE MANUAL
Page
Date
12
MAR 2017
Rev Date
21-53-01 - SPECIAL TOOLS AND/OR EQUIP-
MENT
The following tools and/or equipment are required to
perform expansion valve adjustment:
1. Assorted small hand tools.
2. Inspection mirror , adjustable
3. Thermometer, 0- 150
o
F
4. Flashlight or service light
5. R- 134a service manifold and gauge set
21-53-02 - EVAPORATOR BALANCING PROCE-
DURE
Evaporator balancing is required on all systems with
multiple evaporator modules. This process balances
refrigerant flow between evaporators to achieve equal
evaporator air outlet temperatures. See Section
21-53-03, 1 through 10 above prior to beginning steps
below.
1. Access all evaporator modules and measure/re-
cord outlet air temperatures.
-NOTE-
Typical temperature di fference of evaporator inlet
and outlet air is 25+/- 5
o
F.
2. If suction pressure is above the values outlined in
Section 21-52-03, 13, the adjustment s
crew of the
evaporator expansion valve, which has lowest outlet
temperature, must be turned OUT, in 1/2 revolution in-
crements.
3. Adjust other expansion valve of evaporator that
has higher temperature by turning adjustment screw
IN, in 1/4 revolution increments.
-NOTE-
Proper evaporator balancing should not result in
a change of the compressor suction pressure.
Verify system pressures are within values shown
in Section 21-52-03, 13.
4. Allow system to stabilize 2- 5 minutes; recheck
evaporator outlet temperatures and repeat adjustment
procedure if necessary. Evaporator outlet tempera-
tures should be within 1- 3

F of each other.
5. If evaporator outlet temperatures are equal and
suction pressure meets SECTION 21-52-03, 13, ser-
vicing is complete. If not, repeat SECTIONS 21-53-02
and 21-53-03.
-CAUTION-
Eye and hand protection should be worn dur-
ing this operation.
6. Shut system and aircraft engine OFF. Replace all
shrouds, enclosures, ducting as required; remove
charging manifold gauges and hose assemblies.
21-53-03 - EXPANSION VALVE ADJUSTMENT
The expansion valve adjustment shall be performed in
accordance with, but not limited to the following:
1. Verify that system leak check and refrigerant
charging has been performed and system is operating
at typical values as outlined in Section 21-52-03, 13.
2. Remove all shrouds, covers or enclosures which
prevent access to the evaporator expansion valve ad-
justment knob.
3. Verify R- 134a manifold gauges and hoses are
connected to service ports; manifold gauge set valves
closed.
4. Open both valves on charging hose quick connect
fittings.
5. Remove expansion valves’ protective caps.
6. Verify that inlet to evaporator coil and blower duct-
ing are free of any contamination or restrictions which
could alter air flow.
7. Move aircraft to run- up area. Start aircraft engine.
8. Select ”MAX” on air conditioner switch. Run en-
gine at 1200- 1800 RPM. Verify Alternator is charging.
9. Close cabin and baggage doors and allow system
to operate for 5 minutes.
10. Record compressor suction and discharge pres-
sures and evaporator air inlet and outlet temperatures.
-NOTE-
Typical temperature difference of evaporator inlet
and outlet air is 25+/- 5

F.
11. If suction pressure is above the values outlined in
Section 21-52-03, 13, the adjustment sc
rew of the
evaporator expansion valve, which has lowest outlet
temperature, must be turned OUT, in 1/2 revolution in-
c
rements.
12. Adjust other expansion valve of evaporator that
has higher temperature by turning adjustment screw
IN, in 1/4 revolution increments.
13. Wait 2- 5 minutes for valves to stabilize until de-
sired pressure is obtained, or air outlet temperature is
lowest possible. Re- adjust as necessary.
14. Monitor Engine temperatures and alternator out-
put.
15. If suction pressure is below the values outlined in
Section 21-52-03, 13, the adjustment sc
rew of the
evaporator expansion valve, which has highest outlet
temperature, must be turned IN, in 1/2 revolution incre-
ments.
16. Adjust other expansion valve of evaporator that
has lower temperature by turning adjustment screw
OUT, in 1/4 revolution increments.
17. Operate system for 5- 10 minutes after expan-
sion valve adjustment to verify setting. Evaporator out-
let temperatures should be within 1- 3

F of each other.
18. System contains multiple evaporator modules.
See Section 21-53-02, to balance evaporator modules.
21-53-01