FIELD LEVEL TROUBLESHOOTING INTRODUCTION - Continued
(e) The AC condenser dryer is normally at outside temperature. If the AC condenser dryer is cool or
cool spots form, a blockage has formed in the AC condenser dryer.
(f) A blockage at the inlet of the AC condenser dryer will cause high system high-side pressure.
(g) A blockage at the outlet of the AC condenser dryer will cause low system high-side pressure and
little or no cooling.
(h) If the AC expansion valve is stuck closed, the AC expansion valve and AC evaporator core will be at
(i) If the AC expansion valve is stuck open, the AC expansion valve and AC evaporator core will be
extremely cold and frost or ice buildup may occur.
(j) If ice is forming in the AC expansion valve, the system may stop cooling when the ice forms, and
start cooling when the expansion valve warms up enough to melt the ice, causing the system to
appear to cycle ON and OFF.
(k) A blockage in the AC evaporator core will cause low system low-side pressure and little or no
(l) A leak in the AC evaporator core or AC expansion valve fittings may not be detectable with leak
(m) A restriction in a low system side AC hose will cause low system low-side pressure and little or no
cooling. Cool spots and frost may form at location of restriction.
(n) A restriction in a high system side AC hose will cause high system high-side and low system low-
side pressure and insufficient cooling. Cool spots and frost may form at location of restriction.
6. AC system pressure checks. In addition to the performance checks noted above, the troubleshooting
procedures for the PLS AC system will also include system pressure checks, using standard AC test set
recovery/recycling manifold gages. Before using the manifold gages to measure AC system pressure,
ensure that the system is fully charged, and stabilize the system by ensuring that all cab windows and
vents are closed, personnel heater is OFF, and by running the system at high AC heater/evaporator
blower speed for 5 to 10 minutes.
Refer to TM 9-2320-364-20 for the repair of wire harness connectors. Wire harness repair
d. Wire Repair.
is limited to splicing and taping of wires at Field Level Maintenance. If a wire harness cannot be repaired, notify
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