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SERVICING
NOTE: The Flushing Method using R-11 refrigerant
is no longer approved by Goodman® Manufacturing
Company, L.P.
Suction Line Drier Clean-Up Method
The POE oils used with R410A refrigerant is an excellent
solvent. In the case of a burnout, the POE oils will remove
any burnout residue left in the system. If not captured by
the refrigerant filter, they will collect in the compressor
or other system components, causing a failure of the
replacement compressor and/or spread contaminants
throughout the system, damaging additional components.
The suction line filter drier should be installed as close to
the compressor suction fitting as possible. The filter must
be accessible and be rechecked for a pressure drop after
the system has operated for a time. It may be necessary to
use new tubing and form as required.
NOTE: At least twelve (12) inches of the suction line
immediately out of the compressor stub must be
discarded due to burned residue and contaminates.
1. Remove compressor discharge line strainer.
2. Remove the liquid line drier and expansion valve.
3. Purge all remaining components with dry nitrogen or
carbon dioxide until clean.
4. Install new components including liquid line drier.
5. Braze all joints, leak test, evacuate, and recharge
system.
6. Start up the unit and record the pressure drop across
the drier.
7. Continue to run the system for a minimum of twelve
(12) hours and recheck the pressure drop across the
drier. Pressure drop should not exceed 6 PSIG.
8. Continue to run the system for several days,
repeatedly checking pressure drop across the
suction line drier. If the pressure drop never exceeds
the 6 PSIG, the drier has trapped the contaminants.
Remove the suction line drier from the system.
9. If the pressure drop becomes greater, then it must be
replaced and steps 5 through 9 repeated until it does
not exceed 6 PSIG.
NOTICE: Regardless, the cause for burnout must be
determined and corrected before the new compressor
is started.
Reversing Valve Replacement
Remove the refrigerant charge from the system.
When brazing a reversing valve into the system, it is of
extreme importance that the temperature of the valve does
not exceed 250°F at any time.
Wrap the reversing valve with a large rag saturated with
water. "Re-wet" the rag and thoroughly cool the valve after
each brazing operation of the four joints involved. The wet
rag around the reversing valve will eliminate conduction of
heat to the valve body when brazing the line connection.
The use of a wet rag sometimes can be a nuisance. There
are commercial grades of heat absorbing paste that may
be substituted.
After the valve has been installed, leak test, evacuate and
recharge.
Checking External Static Pressure
The minimum and maximum allowable duct static pressure
is found in the Technical Information Manual.
Too great of an external static pressure will result in
insufficient air that can cause icing of the coil, whereas too
much air can cause poor humidity control, and condensate
to be pulled off the evaporator coil causing condensate
leakage. Too much air can cause motor overloading and in
many cases this constitutes a poorly designed system. To
determine proper air movement, proceed as follows:
1. Using a manometer measure the static pressure
of the return duct at the inlet of the unit, (Negative
Pressure).
Total External Static
2. Measure the static pressure of the supply duct,
(Positive Pressure).
3. Add the two readings together.
NOTE: Both readings may be taken simultaneously
and read directly on the manometer as shown in the
illustration above, if so desired.
4. Consult proper table for quantity of air.
If the external static pressure exceeds the minimum or
maximum allowable statics, check for closed dampers, dirty
filters, undersized or poorly laid out ductwork.
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