|
| |
TM 5-4120-270-15
Incorrectly set or defective
Set valves to correct super-
thermal expansion
heat (para 6-17). Replace
valves
valves if correct adjust-
ment cannot be obtained
or if valves fail to mod-
ulate refrigerant flow
correctly.
Defective solenoid valves
Test control coils (par* 6-
18). Check valves for posi-
tive opening and closing.
Replace defective valve
Defective evaporator fan
Test motor (para 69). Re-
motor
pair or replace if defec-
tive
5-7.
System
Malfunction
or
Combination
of
Malfunctions
Abnormal system oper-
Perform operating pressure
ating pressures
teat (para 6-14).
LOW SUCTION PRES-
SURE
Conditioned area tempera-
Raise thermostat tempera-
ture excessively low
ture sting.
Restricted air flow over
Clean mist eliminator and
evaporator
evaporator coil (para 8-
10), air filters (para 8-
26) and grilles and screens
Incorrectly set or defec-
Set valves to correct super-
tive expansion valve
heat (para --17). Re-
place if defective
Insufficient refrigerant
Test, evacuate and recharge
system (pan 6-28, 29,
80).
Restricted suction line
Replace damaged sections
(par 6B-16).
Incorrectly set or defe-
Set valve to correct super
tive suction pressure
(pan 6-20). Replace if
regulating valve
defective
Defective compressor
Replace compressor (para
-24).
HIGH SUCTION PRES-
SURE
Conditioned area tempera-
Normal operation; self cor-
ture excessively high
recting as temperature
drops
Incorrectly set or defec-
Set valves to correct super-
tive expansion valves
heat (par 6-17). Replace
if defective
Defective hot gas bypass
Test valve (para 6-18). Re
solenoid valve
place if defective.
Defective compressor
Replace compressor (par
5-24).
LOW DISCHARGE
PRESSURE
Insufficient refrigerant
Test, evacuate and recharge
system (para 6-28, 29,
30).
Defective compressor
Replace compressor (para 5-
24).
Probable cause
Possible remedy
HIGH DISCHARGE
PRESSURE
Restricted air flow over
Clean condenser coil (para
condenser
8-11) grille and screens
Incorrectly set or defec-
Set valves to correct super
tive expansion valve
heat (para 6-17). Replace
if defective.
Defective solenoid valve
Test valves (para 6-18).
Replace if defective
Restricted discharge line
Replace damaged
(para 6-16).
Excessive refrigerant
Bleed excess refrigerant
(par 6-28).
5-8.
Blower Motor Fails to Start or Stops on
Overload
Probable cause
Probable remedy
Defective selector switch
Test selector switch (pan
6-2). Replace if defec-
tive
Defective fan motor con-
Test contactor (pan 64).
tactor
Replace if defective
Defective fan motor p
Test relay (r 6-9). Re-
Defective relay
place if defective
Open or shorted control
Perform Continuity t
circuits
(par 6-12). Repair or re
place defective component.
Defective fan motor
Test motor (para 6-). Re
pair or replace if defective.
Defective control circuit
Test transformer (par 6-7).
rectifier
Replace if defective
Defective control circuit
Test rectifier (para 68).
transformer
Replace if defective.
Defective RFI filters
Test RFI filter .(para 68).
Replace if defective.
5-9.
No Heat in "HEAT" Position
Probable cause
Possible remedy
Defective selector switch
Teat selector switch (para
6-2). Replace if defective.
Defective temperature con-
Test thermostat (para .6-3)
trol thermostat
Replace if defective
Defective heater high tem-
Test high temperature cutout
perature cutout
(para 6-11). Replace if
defective
Defective or damaged heat-
Test heater (p 6-10).
er elements
Replace if damaged or
defective
Defective heater contactors
Test contactors (para 6-5).
Replace if defective.
Open or shorted control cir
Perform continuity tests
cuits
(para 6-12). Repair or re
place defective component.
Defective control circuit
Test transformer (pen 6-7).
transformer
Replace if defective
Defective control circuit
Test rectifier (para -8).
rectifier
Replace if defective
Defective RFI filters
Test RFI filters (part 8-8).
capacitors
Replace if defective
5-2
|
