Amana ASH13018 Service Manual download pdf (Page 52)

SERVICING

24Vac from “W2” and the VSTB will remove the 24Vac

from HR2. The contacts on HR2 will open between 30 to

70 seconds and heater elements #3 and #4 will be turned

off and the blower motor will change to low speed. On

most digital/electronic thermostats, “W2” will re-

main energized until the first stage demand “W1” is

satisfied and then the “W1” and “W2” demands will

be removed.

2.3 When the “W1” heat demand is satisfied, the room

thermostat will remove the 24Vac from “E/W1” and the

VSTB removes the 24Vac from HR1. The contacts on

HR1 will open between 30 to 70 seconds and turn off the

heater element(s) and the blower motor ramps down to a

complete stop.

S-41A AEP* & MBE WITH SINGLE STAGE HEAT

PUMPS

When used with a single stage heat pump, dip switch #4 must

be set to the ON position on the VSTB inside the MBE. The

“Y” output from the indoor thermostat must be connected to

the yellow wire labeled “Y/Y2” inside the wire bundle marked

“Thermostat” and the yellow wire labeled “Y/Y2” inside the

wire bundle marked “Outdoor Unit” must be connected to “Y”

at the heat pump. The orange jumper wire from terminal

“Y1” to terminal “O” on the VSTB inside the MBE must

be removed.

3.0 Cooling Operation

On heat pump units, when the room thermostat is set to the

cooling mode, 24Vac is supplied to terminal “O” of the VSTB

inside the MBE unit. The VSTB will supply 24Vac to “O” at

the heat pump to energize the reversing valve. As long as the

thermostat is set for cooling, the reversing valve will be in the

energized position for cooling.

3.1 On a demand for cooling, the room thermostat energizes

“G” and “Y” and 24Vac is supplied to terminals “G” and “Y/

Y2” of the MBE unit. The VSTB will turn on the blower

motor and the motor will ramp up to the speed pro-

grammed in the motor based on the settings of dip switch

5 and 6. The VSTB will supply 24Vac to “Y” at the heat

pump.

3.2 The heat pump is turned on in the cooling mode.

3.3 When the cooling demand is satisfied, the room thermo-

stat removes the 24Vac from “G” and “Y/Y2” of the MBE

and the VSTB removes the 24Vac from “Y” at the heat

pump. The heat pump is turned off and the blower motor

will ramp down to a complete stop based on the time and

rate programmed in the motor.

4.0 Heating Operation

On heat pump units, when the room thermostat is set to the

heating mode, the reversing valve is not energized. As long

as the thermostat is set for heating, the reversing valve will be

in the de-energized position for heating except during a

defrost cycle. Some installations may use one or more

outdoor thermostats to restrict the amount of electric heat

that is available above a preset ambient temperature. Use of

optional controls such as these can change the operation of

the electric heaters during the heating mode. This sequence

of operation does not cover those applications.

4.1 On a demand for first stage heat with heat pump units, the

room thermostat energizes “Y” and “G” and 24Vac is

supplied to “G” and “Y/Y2” of the MBE. The VSTB will turn

on the blower motor and the motor will ramp up to the

speed programmed in the motor based on the settings of

dip switch 1 and 2. The VSTB will supply 24Vac to “Y” at

the heat pump and the heat pump is turned on in the

heating mode.

4.2 If the first stage heat demand cannot be satisfied by the

heat pump, the temperature indoors will continue to drop.

The room thermostat will then energize terminal “W2” for

second stage heat and 24Vac will be supplied to “E/W1”

of the MBE. The VSTB will supply 24Vac to heat

sequencer, HR1, on the electric heater assembly.

4.3 HR1 contacts M1 and M2 will close within 10 to 20

seconds and turn on heater element #1. At the same

time, if the heater assembly contains a second heater

element, HR1 will contain a second set of contacts, M3

and M4, which will close to turn on heater element #2.

Note: If more than two heater elements are on the heater

assembly, it will contain a second heat sequencer, HR2,

which will control the 3

and 4

heater elements if available.

For the 3

and 4

heater elements to operate on a third

stage heat demand, the PJ4 jumper on the VSTB inside

the MBE and AEP* must be cut. If the second stage heat

demand, “W2”, cannot be satisfied by the heat pump, the

temperature indoors will continue to drop. The room thermo-

stat will then energize “W3” and 24Vac will be supplied to “W/

W2” of the MBE. The VSTB will supply 24Vac to HR2 on the

electric heater assembly. When the “W3” demand is satis-

fied, the room thermostat will remove the 24Vac from “W/W2”

of the MBE and AEP*. The contacts on HR2 will open

between 30 to 70 seconds and heater elements #3 and #4 will

be turned off. On most digital/electronic thermostats,

“W3” will remain energized until the first stage de-

mand “Y” is satisfied and then the “G”, “Y”, “W2” and

“W3” demands will be removed.

4.4 As the temperature indoors increase, it will reach a point

where the second stage heat demand, “W2”, is satisfied.

When this happens, the room thermostat will remove the

24Vac from “E/W1” of the MBE. The contacts on HR1 will

open between 30 to 70 seconds and turn off both heater

element(s). The heat pump remains on along with the

blower motor because the “Y” demand for first stage heat

will still be present.

4.5 When the first stage heat demand “Y” is satisfied, the

room thermostat will remove the 24Vac from “G” and “Y/

Y2” of the MBE and AEP*. The VSTB removes the 24Vac

from “Y” at the heat pump and the heat pump is turned off.

The blower motor will ramp down to a complete stop

based on the time and rate programmed in the motor

control.

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Amana ASH13018 Service Manual Page 52

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