27
Scholar V VAIVA Maintenance & Service Manual 10/2017 Rev.2
Item
No. Description
1
Compressor---permanent magnet motor--variable speed.
3
Compressor Controller---electronic controller used to control speed of compressor.
Takes a 24 VAC signal from PLC for On-Off and a 10 VDC signal from PLC for speed.
3
High Pressure Switch---input to PLC---open on pressure rise of the condenser.
4
Loss of Charge Switch---input to PLC---open on pressure fall when there is a significant loss of refrigerant.
5
Discharge Thermostat---input to PLC--open on temp. rise.
6
Muffler---helps reduce pulsations and vibration.
7
Check Valve---prevents high pressure gas from flowing backwards on off cycle.
8
Hot Gas Valve---controls flow of hot gas into reheat coil during dehumidification.
9
Reversing Valve---switches refrigerant flow direction for cooling and heating modes.
10
Compensator---stores excess refrigerant in heating mode.
11
Outdoor Coils---heat exchangers to reject heat during cooling and absorb heat during heating.
12
Outdoor Distributors with Orifice---fixed expansion device during heating---balances refrigerant flow through individual coil circuits-
--internal check valve for cooling mode.
13
Coil #1 Thermocouple---measures temperature of Coil #1 distributor tube bundle for head pressure and defrost control---analog input
to PLC.
14
Coil #2 Thermocouple---measures temperature of Coil #2 distributor tube bundle for head pressure and defrost control---analog input
to PLC.
15
Sight Glass---used for observing refrigerant flow---helpful in charging the system.
16
Filter Drier---used to remove moisture and debris from the refrigeration system.
17
Electronic Expansion Valve (EEV)---stepper motor driven valve to accurately control superheat.
18
EEV Controller---electronic controller to provide signal to EEV to drive stepper motor.
19
EEV Temperature Sensor---measures temperature of evaporator outlet pipe---Sends temperature value to EEV controller for super-
heat calculation.
20
EEV Pressure Transducer---measures pressure at outlet of evaporator---Sends pressure value to EEV controller for superheat calcu-
lation.
21
Check Valve---allows condensed refrigerant to bypass EEV during heating mode.
22
Indoor Distributor---mixes and distributes two phase refrigerant to indoor coils during cooling.
23
Distributor Tubes---used to transfer two phase refrigerant during cooling and condensed liquid during heating.
24
Indoor Coils---heat exchangers to abosrb heat during cooling and reject heat during heating.
25
Suction Accumulator---storage vessel to prevent liquid from flowing to compressor. Used primarily during defrost cycle.
26
Reheat Coils---used during dehumidification to heat air back to room temperature so overcooling of space is not a problem.
27
Reheat Check Valve---used when reheat is not active to prevent refrigerant from entering reheat coils.
28
Outdoor Blowers (fans)---air movers used to pull air through outdoor coils to reject heat in cooling and absorb heat in heating. ECM
type motor for speed control.
29
Outdoor Blower Controllers---used to set the speed of outdoor blower motors with pulse width modulation (PWM).
30
Indoor Blower Motor---air movers used to pull air through indoor coils to reject heat in heating and absorb heat in cooling. ECM type
motor for speed control.
31
Indoor Blower Motor Controller---used to set speed of the indoor motor. Receives speed input from PLC---uses puls width modulation
(PWM).
32
Electric Resistance Heater---electric heater in the supply air stream---used as backup heater and to provide heating during the defrost
cycle.
33
Supply Air Thermocouple---measures temperature of supply air leaving the unit to control hot gas reheat
34
Ventilation Blower---motorized blower that pulls outside air and puts it in the room
35
Motorized Damper---damper which cloes when no ventilation is required---opens to a preset position when ventilation is desired in the
room.
36
High Side Schraeder Valve---used to attach refrigeration gauges to the high pressure side of the unit.
37
Low Side Schraeder Valve---used to attach refrigeration gauges to the low pressure side of the unit.
38
Blower Current Switch (optional).
39
Compressor Current Switch (optional).
