McQuay SEASONCON ALP-037A, Manual, Page: 38 / 43

I N - W A R R A N T Y R E T U R N M A T E R I A L P R O C E D U R E
COMPRESSOR
Copeland Refrigeration Corporation has stocking whole-
salers who maintain a stock of replacement compressors
and service parts to serve refrigeration contractors and
servicemen.
When a compressor fails in warranty, contact your local
sales representative, or McQuay Warranty Claims Depart-
ment at the address on the cover of this bulletin. You will
be authorized to exchange the defective compressor at a
Copeland Wholesaler, or an advance replacement can be
obtained. A credit is issued to you by the wholesaler for the
returned compressor after Copeland factory inspection of
the inoperative compressor. If that compressor is out of
Copeland’s warranty, a salvage credit only is allowed. Pro-
vide McQuay with full details: McQuay unit model and unit
serial numbers. Include the invoice and the salvage value
credit memo copies and we will reimburse the difference. In
this transaction, be certain that the compressor is definitely
defective. If a compressor is received from the field that
tests satisfactorily, a service charge plus a transportation
charge will be charged against its original credit value.
On all out-of-warranty compressor failures, Copeland
offers the same field facilities for service and/or replace-
ment as described above. The credit issued by Copeland on
the returned compressor will be determined by the repair
charge established for that particular unit.
COMPONENTS OTHER THAN COMPRESSORS
Material may not be returned except by permission of
authorized service personnel of McQuay Inc. at Minne-
apolis, Minnesota. A “Return Goods” tag will be sent to be
included with the returned material. Enter the information
as called for on the tag in order to expedite handling at our
factories and prompt issuance of credits.
The return of the part does not constitute an order for
replacement. Therefore, a purchase order must be entered
through your nearest McQuay Representative. The order
should include part name, part number, model number and
serial number of the unit involved.
Following our personal inspection of the returned part,
and if it is determined that the failure is due to faulty
material or workmanship, and in warranty, credit will be
issued on customer’s purchase order.
All parts shall be returned to the pre-designated McQuay
factory, transportation charges prepaid.
A P P E N D I X
S T A N D A R D C O N T R O L S
NOTE: PERFORM AN OPERATIONAL CHECK OF ALL UNIT SAFETY CONTROLS ONCE PER YEAR.
OIL PRESSURE SAFETY CONTROL
The oil pressure safety control is a manually resettable
device which senses the differential between oil pressure at
the discharge of the compressor oil pump and suction pres-
sure inside the compressor crankcase. When the oil pressure
reaches approximately 15 PSI above the crankcase suction
pressure, the pressure actuated contact of the control opens
from its normally closed position. If this pressure differ-
ential cannot be developed, the contact will remain closed
and energize a heater element within the control. The
heater element warms a normally closed bimetallic contact
and causes the contact to open, de-energizing a safety relay
and breaking power to the compressor.
It takes about 120 seconds to warm the heater element
enough to open the bimetallic contact, thus allowing time
for the pressure differential to develop.
If during operation, the differential drops below 10 PSI,
the heater element will be energized and the compressor
will stop. The control can be reset by pushing the reset
button on the control. If the compressor does not restart,
allow a few minutes for the heater element and bimetallic
contacts to cool and reset the control again.
To check the control, pump down and shut off all power
to the unit. Remove the compressor fuses, and install a
voltmeter between terminals “L” and “M” of the oil pres-
sure control. Turn on power to the unit control circuit
(separate disconnect or main unit disconnect depending on
the type of installation). Check to see that the control stop
s w i t c h
is in the “on” position. The control circuit
should now be energized, but with the absence of the com-
pressor fuses, no oil pressure differential can develop and
thus, the pressure actuated contacts of the control will
energize the heater element and open the bimetallic con-
tacts of the control within 120 seconds. When this happens,
the safety relay is de-energized, the voltmeter reading will
rise to 115V, and the compressor contactor should open.
Repeated operations of the control will cause a slight heat
buildup in the bimetallic contacts, resulting in a slightly
longer time for reset with each successive operation.
T2
120
LINE (SEE NOTE
NEUTRAL
HEATER ELEMENT
CONTACT
L
LINE (SEE NOTE 21 NEUTRAL
BIMETALLIC CONTACTS SAFETY RELAY
NOTES:
1. Hot only when the unit thermostat calls for compressor
to run.
2. Hot only when other safety control contacts are closed.
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