TM 9-4120-401-14
Section V UNIT TROUBLESHOOTING
USE OF TROUBLESHOOTING TABLE.
Table 4-2 contains troubleshooting information useful to unit maintenance technicians in diagnosing and
correcting malfunctions or unsatisfactory operation of the air conditioner.
a. The Table lists the common malfunctions which you may find during the operation or maintenance of the air
conditioner or its components. You should perform the test/inspection and corrective actions in the order listed.
b. This manual cannot list all malfunctions that may occur, nor all tests or inspections and corrective actions. If
a malfunction is not listed or is not corrected by listed corrective actions, notify your supervisor.
SYMPTOM INDEX
Trouble
Malfunction No.
AIR CONDITIONER
Does Not Start In Any Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reduced Cooling Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reduced Heating Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No Heat In Heat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Excessively Noisy Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EVAPORATOR
Evaporator or Condenser Fan Motor Does Not Operate . . . . . . . . . . . . . . . . . . . . .
CONDENSER
Evaporator or Condenser Fan Motor Does Not Operate . . . . . . . . . . . . . . . . . . . . .
COMPRESSOR
Fans Run But Compressor Does Not Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Starts Normally, But Soon Stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Starts Normally, But High Pressure Cutout Switch Trips.. 4
UNIT
TROUBLESHOOTING
MALFUNCTION
TEST OR INSPECTION
C O R R E C T I V E ACTION
AIR CONDITIONER DOES NOT START IN ANY MODE.
Use disconnect switch (NOT POWER CABLE) to connect power to unit. Damage
to cable connector pins will result if cable is used.
If input power has been disconnected for an unknown period of time, do not start
in COOL MODE until power has been reconnected for a minimum of six hours.
Step 1. Check to see if input power has been disconnected.
Connect input power.
