SECTION IV. UNIT MAINTENANCE TROUBLESHOOTING

TM 55-1905-223-24-17

SECTION IV. UNIT MAINTENANCE TROUBLESHOOTING

2-11.

Symptom Index. Both a symptom index and a troubleshooting table are provided. The symptom

index will help you locate the information you need for troubleshooting.

SYMPTOM INDEX

Troubleshooting

Procedure

(Table 2-2)

HEATING

No heat - blower running

Item 2

No heat - no blower

Item 1

Not enough heat

Item 3

VENTILATION (FANS)

Air flow too high

Item 6

Air flow too low

Item 5

Excessive noise or vibration

Item 4

Fan does not operate

Item 7

AIR CONDITIONING

Cold or frosted liquid line (or line component)

Item 14

Compressor crankcase cold (sweating or

Item 11

frosting)

Compressor noises

Item 20

Compressor or compressor motor hums but does

Item 16

not start

Compressor runs continuously

Item 19

Compressor short cycles on high pressure cut-out

Item 17

Compressor short cycles on low pressure cut-out

Item 18

Compressor will not start

Item 15

High crankcase temperature (compressor

Item 12

extremely hot)

High operating head (discharge) pressure

Item 8

High suction pressure

Item 10

Hot liquid line

Item 13

Low operating head (discharge) pressure

Item 9

No cooling - blower does not run

Item 22

No cooling - blower running

Item 23

Partial or insufficient cooling - blower

Item 24

running

Piping rattles

Item 21

Water leaking from the unit

Item 25

ALL HVAC EQUIPMENT

Contactor chatter

Item 27

Unit gives electrical shock

Item 26

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