CSCF R-22 Service Manual

ManualsBrandsGoodman ManualsEvaporator Coils2.5 to 3 Ton Horizontal Slab Evaporator Coil

SERVICING

4.4 In order to make sure the blower is running when heat is

on, the normally closed contacts on the EBTDR will

power the blower motor if no G signal is received.

4.5 There may be delay on activation or deactivating heater

elements.

5.0 Defrost 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.

5.1 The heat pump will be on and operating in the heating

mode as described the Heating Operation in section 4.

5.2 The defrost control in the heat pump unit checks to see

if a defrost is needed every 30, 60 or 90 accumulated of

compressor runtime minutes of heat pump operation

depending on the selectable setting by monitoring the

state of the defrost thermostat attached to the outdoor

coil.

5.3 If the temperature of the outdoor coil is low enough to

cause the defrost thermostat to be closed when the

defrost board checks it, and if accumulated compressor

runtime of 30, 60 or 90 minutes expires the board will

initiate a defrost cycle.

5.4 When a defrost cycle is initiated, the contacts of the

HVDR relay on the defrost board open and turns off the

outdoor fan. The contacts of the LVDR relay on the

defrost board closes and supplies 24Vac to “O” and “W2”.

The reversing valve is energized and 1st stage of elec-

tronic heat is energized. The unit will continue to run in

this mode until the defrost cycle is completed, or maxi-

mum defrost time of 12 minutes expires.

a. For models with defrost control PCBDM133, a 30

second compressor delay at defrost initiation/termina-

tion is optional. As shipped from the factory, the

control is set for the delay (“DLY”), which will turn the

compressor off for 30 seconds at entering and exiting

defrost operation while the reversing valve shifts to/

from the cooling mode position. To bypass the delay,

which typically reduces sound levels during defrost

mode, change the pin settings from “DLY” to “NORM”.

5.5 When the defrost cycle is terminated, the contacts of the

HVDR relay will close to start the outdoor fan and the

contacts of the LVDR relay will open and turn off the

reversing valve and electric heater(s). The unit will now be

back in a normal heating mode with a heat pump demand

for heating as described in the Heating Operation in

section 4. See section 5.4a.

S-41 AEP* & MBE WITH SINGLE STAGE CON-

DENSERS

AEP* & MBE ELECTRONIC BLOWER TIME DELAY RELAY

SEQUENCE OF OPERATION

This document covers the basic sequence of operation for a

typical application with a mercury bulb thermostat. When a

digital/electronic thermostat is used, the on/off staging of the

auxiliary heat will vary. Refer to the installation instructions

and wiring diagrams provided with the MBE for specific wiring

connections, dip switch settings and system configuration.

AEP* & MBE WITH SINGLE STAGE CONDENSERS

When used with a single stage condenser, 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 condenser. The orange jumper wire

from terminal “Y1” to terminal “O” on the VSTB inside the

MBE must remain connected.

1.0 Cooling Operation

1.1 On a demand for cooling, the room thermostat energizes

“G” and “Y” and 24Vac is supplied to “G” and “Y/Y2” of the

MBE unit. The VSTB inside the MBE will turn on the

blower motor and the motor will ramp up to the speed

programmed in the motor based on the settings for dip

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

condenser and the compressor and condenser are turned

on.

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

stat removes the 24Vac from “G” and “Y”. The MBEand

AEP* remove the 24Vac from “Y’ at the condenser and the

compressor and condenser fan are turned off. The blower

motor will ramp down to a complete stop based on the

time and rate programmed in the motor.

2.0 Heating Operation

2.1 On a demand for heat, the room thermostat energizes

“W1” and 24Vac is supplied to terminal “E/W1” of the

VSTB inside the MBEand AEP* units. 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 for

dip switch 1 and 2. The VSTB will supply 24Vac to heat

sequencer HR1 on the electric heater assembly.

2.2 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 and 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 second stage heat demand, the PJ4

jumper on the VSTB inside the MBE and AEP* must

be cut. With the PJ4 jumper cut, the VSTB will run the

blower motor on low speed on a “W1” only demand. If the

first stage heat demand, “W1” cannot be satisfied by the

heat pump, the temperature indoors will continue to drop.

The room thermostat will then energize “W2” and 24Vac

will be supplied to HR2 on the heater assembly and the

blower motor will change to high speed. When the “W2”

demand is satisfied, the room thermostat will remove the