Specifications

ManualsBrandsYork ManualsBlower480

530 .25-N1

2. Turn the rninlrnum outsde ~lr adjustor to the 07 outsde

tiir pos]tmn, All outsde air damper blades should be fully

closed. The linkage connect ing the outwle

iIII and the re-

turn air darnpels must move freely.

3. Return the mmlrnurn outside alr adjustor to the 1009I

outside alr position tind check for complete freedom of

linkage movement as the return alr dampers close.

4. Set the mmimurn outside alr tid]ustur for the minimum

ventilation requirement of the job,

HEATING SYSTEM

Two different types 01’beat are offered as factory-mounted

opt Ions, Refer to t}le apprwprmte mstruction for mt_orma-

tion on the heating system.

Gas-Fired Heating Opt Ion

- Form 530.25-N 1.1

Flectrlc Heating Option Form 530.25-N 1.9

COOLING SYSTEM

These units have nominal cooling capacities of 25, 30 and

40 tons. The DSC300 and DSC360 units have one semi-her-

metic compressor. Two cooling stagesare accomplished by

unloading the compressor. The DSC480 unit has two semi-

hermetic compressors. Two cooling stagesare accomplished

by cycling the individual compressors.

Normal sequence of operation is os follows:

Power is supplied to the unit through the disconnect

switch. The swlt cl] can be field installed or factory-

installed as an option.

As soon as power ISsupphed to the unit, the compressor

crankcase heaters 1TI { (and 2T1I ) WII1 be enelgi~ed,

CAUTION: Do m)t attempt to start ttw cc)ntpressors

Wi[jjc)li[at [east~ /lorirs~)j~rankc,asc~jt~at

or c~)nlpressordut)rage}t’i[[occur

The system switch on the room thermostat or the stfitus

panel must be in the ALITO or COOL posltmn to com-

plete the circuit between the terminals 119 and 103/RC

On demand of the rotirn thel-mos[at for cooling, contact

TC I closesand energl~es I R coil.

An internal connection in the thermostat or status panel

energizes 7R cod. 7R contact closesenerguing 3M cod.

3M contacts close, starting the sLIpply alr fan motor. Af-

ter an adequate air flow ISestablished, 5 LP closesto en-

ergize 6R cod. 6R contact closes m the compressor con-

trol circuit,

IVOT[<:TIIC)above t)peratit)nisj))r internlittent jan opera-

tion. For continuous op]ratiotl, the fan switch on

the morn thernmtat or the ~tatusIxrne[sh(M~kibe

nwnually closed to energize 7R.

Relay contact 1R closesand energl/es 1M c(J1l,which

starts the No. 1 compressor. At the same time,

4M COIIIS

energized to start the condenser fwls.

[f the room temperature continues to rise, c(mtact T(’2

doses and energizes 2R coil,

On DSC480 units the 2R contacts close, energizing the

2M coil which starts the No. 2 compressor or on DS(’300

and DSC360 units the 2R contacts close de-energizing

the compressor unloading solen[)ld which kinds the ct)m-

presser.

The compressor short cycle time and low voltage pro-

tection is part of the solid state compressor protection

module. 1[ prevents a compressor from starting unless it

has been off for five minutes. It also monitors the v[)lt-

age of the 120 volt cent rol circuit and will shut down

the compressor if the 120 volt control voltage drops be-

low 85+4.5 volts,

To rna]ntain sufficient head pressure during low ambient

operation. condenser fan No, 1 on the DSC 300 unit and

condenser fans No, 1 and No. 2 on the DSC 360 and DSC

480 units will be Lle-cnergl/ed by ITH. Condenser fan

No. 2 on the DSC300 unit tind condenser fans No. 3 and

4 on the DSC360 and DSC’480 will be Llc-energved by

2TH (see Table 6).

EXHAUST

AIR SYSTEM

The exhaust air fans are energiled by nuinually closlng a cir-

cuit between termmals 60 and 64 of terminal block 2TB or

autorntrtically by an end switch on the economizer damper

mot or, As the economl~e r damper open$, it closesthe end

swltcb on the dtiroper motor and turns (m the exlla USIaIr

fans. The degree of blade [)~nlng at which the exhaust f’an~

are energl~ed can be adjusted by the folk~wlng procedure.

Use the black scale plate as an indlcatc)r of motor position”

for swltch operation.”

Loosen the thumb nut and the

cam lock]ng screws.

Set the opclationa[ and dii (erent lal c~n]~.

Check swltcb adjustment by muving the ~dJustor .2RII to

move the motor. Swit CII should click when deslled make

and break points are lined up with index mark :ind tIIe

exhaust fon stx)uId st~rt and stop.

h51RI\’1,1’G ]~{) L$cj[[

po~treris CY)IItUrCled t{)[ho$1%’i[c’h.

T]gbten thumb nut,

CES