Compressor Does Not Run; Troubleshooting Guide - Carrier 38AD Installation, Start-Up And Service Instructions Manual

To Add or Remove Compressor Oil
1. Pump down compressor to 2 psig and close
suction and discharge service valves. Vent re¬
maining pressure in compressor to atmosphere.
2. Add oil thru oil filler connection.
3. To remove oil, remove compressor crankcase oil
drain plug.
Refer to Carrier Standard Service Techniques
Manual, Chapter 1, for complete instructions on
checking, adding or removing compressor oil.
Cleaning Coils — The coils can be cleaned with a
vacuum cleaner, washed out with water, blown out
with compressed air, or brushed. Fan motors are
drip proof but not waterproof.
TROUBLESHOOTING GUIDE
COMPRESSOR DOES NOT RUN
Contactor Open
Power off — restore power.
Fuses blown — replace with correct fuses.
Control circuit breaker open - check for short circuit in
control wiring.
Transformer dead — replace transformer if primary
windings are receiving power.
Thermostat circuit open — check thermostat setting.
Timer motor defective — replace timer.
Compressor lockout circuit open — check for excessive
compressor current draw (140% FLA max allowable) or
excessive motor temperature (motor thermostat opens).
After corrective action, press reset button.
Low-pressure switch open — check for refrigerant
undercharge or obstruction of indoor air flow.
High-pressure switch open — check for refrigerant
overcharge or obstruction of outdoor air flow.
Connections loose — tighten all connections.
Compressor stuck — see 06D service literature.
Contactor Closed
Compressor leads loose — check connections.
Motor windings open — see 06D compressor service
literature.
Single phasing - replace blown fuse.
Contactor Closed Then Open
If compressor lockout circuit is open — see Contactor
Open.
If compressor lockout circuit is closed — see Compressor
Cycles on High- (or Low-) Pressure Switch.
COMPRESSOR CYCLES ON HIGH-PRESSURE
SWITCH
Condenser Fan On
High-pressure switch faulty — replace switch.
Air flow restricted — remove obstruction.
Air recirculating — clear airflow area.
Noncondensables in system — purge and recharge as
required.
Refrigerant overcharge - purge as required.
Line voltage incorrect — consult power company.
Refrigerant system restrictions — check or replace
filter-drier, expansion valve, etc.
Condenser Fan Off
Fan slips on shaft
— tighten fan hub setscrews.
Motor not running
— check power and capacitor.
Motor bearings stuck
— replace bearings.
Motor overload open
— check overload rating. Check for
fan blade obstruction.
Motor burned out
— replace motor.
COMPRESSOR CYCLES ON LOW-PRESSURE
SWITCH
Evaporator Air Fan Running
Filter-drier plugged
— replace filter-drier.
Expansion valve power head defective
— replace power
head.
Low refrigerant charge
— add charge. Check low-
pressure switch setting.
Air Flow Restricted
Coil iced up
— check refrigerant charge.
Coil dirty
— clean coil fins.
Air filter dirty
— clean or replace filters.
Dampers closed
— check damper operation and position.
Evaporator Air Fan Stopped
Electrical connections loose
— tighten all connections.
Fan relay defective
— replace relay.
Motor overload open
— power supply.
Motor defective —
replace motor.
Fan belt broken or slipping
— replace or tighten belt.
COMPRESSOR RUNS BUT COOLING
INSUFFICIENT
Suction Pressure Low
Refrigerant charge low
— add refrigerant.
Low-pressure switch setting too high
— adjust to correct
setting.
Head pressure low
— check refrigerant charge. Check
condenser air fan thermostat settings.
Air filters dirty
— clean or replace filters.
Expansion valve power head defective
— replace power
head.
Evaporator coil partially iced
— check low-pressure
setting.
Evaporator air flow restricted
— remove obstruction.
Suction Pressure High
Compressor valves defective
— see 06D service literature.
Heat load excessive
— check for open doors or windows.
For replacement items use Carrier Specified Parts.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Tab 4
Form 38AD-4SI Supersedes 38AD-3SI Printed in U.S.A 474 9-71 Codes B and MS Catalog No. 533—824