Goodman [A/G]PG, Service Instructions Manual

SERVICING

37

1. Remove the leads from the compressor terminals.

See warnings S-17  before removing compressor
terminal cover.

2. Using an ohmmeter, test continuity between ter-

minals S-R, C-R, and C-S, on single phase units or termi-
nals T1, T2 and T3, on 3 phase units.

S

R

C

COMP

OHMMETER

TESTING COMPRESSOR WINDINGS

If either winding does not test continuous, replace the com-
pressor.

NOTE: 

 If an open compressor is indicated allow ample time

for the internal overload to reset before replacing compressor.

S-17B Ground Test

If fuse, circuit breaker, ground fault protective device, etc., has
tripped, this is a strong indication that an electrical problem
exists and must be found and corrected. The circuit protective
device rating must be checked and its maximum rating should
coincide with that marked on the equipment nameplate.

With the terminal protective cover in place, it is acceptable to
replace the fuse or reset the circuit breaker ONE TIME ONLY
to see if it was just a nuisance opening.  If it opens again, DO
NOT continue to reset.

Disconnect all power to unit, making sure that all power legs
are open.

1. DO NOT remove protective  terminal cover. Disconnect the

three leads going to the compressor terminals at the near-
est point to the compressor.

Damage can occur to the glass embedded terminals if
the leads are not properly removed. This can result in
terminal and hot oil discharging.

HI-POT

COMPRESSOR GROUND TEST

2. Identify the leads and using a Megger, Hi-Potential Ground

Tester, or other suitable instrument which puts out a volt-
age between 300 and 1500 volts, check for a ground sepa-
rately between each of the three leads and ground (such
as an unpainted tube on the compressor).  Do not use a
low voltage output instrument such as a volt-ohmmeter.

3. If a ground is indicated, then carefully remove the compres-

sor terminal protective cover and inspect for loose leads or
insulation breaks in the lead wires.

4. If no visual problems indicated, carefully remove the leads

at the compressor terminals.

Carefully retest for ground, directly between compressor
terminals and ground.

5. If ground is indicated, replace the compressor.

S-17C Unloader Test Procedure

A nominal 24-volt direct current coil activates the internal
unloader solenoid. The input control circuit voltage must be 18
to 28 volt ac. The coil power requirement is 20 VA. The exter-
nal electrical connection is made with a molded plug assem-
bly. This plug contains a full wave rectifier to supply direct
current to the unloader coil.

UNLOADER SOLENOID

(Molded Plug)

Unloader Test Procedure

If it is suspected that the unloader is not working, the
following methods may be used to verify operation.

1. Operate the system and measure compressor current.

Cycle the unloader ON and OFF at 10 second intervals.
The compressor amperage should go up or down at least
25 percent.

2. If step one does not give the expected results shut unit off.

Apply 18 to 28 volt ac to the unloader molded plug leads
and listen for a click as the solenoid pulls in. Remove power
and listen for another click as the unloader returns to its
original position.

3. If clicks can’t be heard, shut off power and remove the con-

trol circuit molded plug from the compressor and measure
the unloader coil resistance. The resistance should be 32
to 60 ohms, depending on compressor temperature.