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TM 5-4120-287-15
(10) If thermostat does not meet criteria
established in e (4), (5) and (8) of this
paragraph, it is defective and must be
replaced.
f.
Solenoid Valve Coil L101. Test solenoid
valve coil as follows:
(1)
With air conditioner running in COOL
mode and Temperature control switch set to
maximum warm, place thermostat S105 in
water having a temperature of 40 + 50F.
SECTION III.
ELECTRICAL TRAY ASSEMBLY
6-7.
General
The electrical tray assembly consists of the
following items (figs. 23 and 6-3): Master
circuit breaker, CB1; 28-volt, 3/4 amp fuse
holder, Fl; system reset switch, S1; elapsed
time hourmeter, M1; power transformer, T1;
silicon rectifier, CR1; control relays and line
contactor relays, K101 thru K108; and asso-
ciated wiring harness assemblies.
6-8.
Removal
Remove electrical tray assembly (para 5-19).
6-9.
Testing
Warning: Make sure master circuit break-
er is set to OFF position and power supply is
disconnected from POWER INPUT recepta-
cle J101 when preparing for tests and con-
necting test leads.
a.
Master Circuit Breaker (CB1).
(1)
Check power supply "hot" leads for
240-vac volts alternating current potential to
ground.
(2)
Connect power supply to input pow-
er receptacle J101.
(3)
Set master circuit breaker to ON
position.
(4)
Using a multimeter check for 240
vac potential between ground and each of the
three CB1 terminals, marked B.
(5)
If reading is not obtained circuit
breaker CB1 is defective and should be
replaced.
b.
28-volt Power Supply.
(1) Fuse (F1).
6-6
(2)
Disconnect solenoid valve coil leads
from terminal Board TB1.
(3)
Apply 28VDC across solenoid valve
coil leads and note refrigerant flowing
through refrigerant liquid sight indicator.
Remove 28VDC supply and note that refrig-
erant flow ceases.
(4)
Replace a defective solenoid valve
coil with a new part.
(a)
Check fuse and fuse holder (para
337).
(b)
Replace a defective fuse and/or
fuse holder.
(2)
Phase sequence relay (K108).
(a)
Using a multimeter, check for 416
vac across relay K108 terminals L1 and A2.
(b)
If reading is not obtained, the
phase sequence relay K108 is defective and
must be replaced.
(3)
Power Transformer (T1).
(a)
Shunt transformer terminals 6 and
7 with a 25-ohm resistor rated at 50 watts.
(b)
Using a multimeter, check for
30.2 + I across transformer terminals 6 and 7.
(c)
Remove shunt.
(d)
Shunt transformer terminals 5 and
6 with a 25-ohm resistor rated at 50 watts.
(e)
Using a multimeter, check for
30.2 +1 vac across transformer terminals 5
and 6.
(f)
Remove shunt.
(g)
If readings specified in b(3)b
and (e) are not obtained power transformer
T1 is defective and must be replaced.
(4)
Rectifier (CR1).
(a)
Shunt rectifier (CR1) terminal C
and transformer (T1) terminal 6 with a 25-
ohm resistor rated at 50 watts.
(b)
Using a multimeter, check for a
nominal value of 28 vdc (volts direct current)
across transformer terminal 6 and rectifier
terminal C.
(c)
If reading is not obtained, recti-
fier CR1 is defective and must be replaced.
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