Bosch TA025 Installation And Maintenance Manual Download Page 8

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Subject to change without prior notice Revised 03-11

6 720 220 046

TA Series

If the thermostat is provided with a malfunction
light powered off of the common (C) side of the
transformer, the unit must be provided with a
malfunction relay (Bosch option # 660-006) to
properly energize the light. The relay coil will
be wired across the (ALR) and (C) contacts on
the unit’s UPM board and the relay’s normally
open contacts across (ALR) and the
malfunction light connection on the
thermostat. If the thermostat is provided with a
malfunction light powered off of the hot (R)
side of the transformer, then the thermostat
malfunction light connection should be
connected directly to the (ALR) contact on the
unit’s UPM board.

To the left of the thermostat connection block are a
row of 2 red and 4 green LED’s. These LED’s indicate
the operating status of the unit. They are labeled as
follows:
EM (red)

Emergency Heat On

W1 (red)

Auxiliary Heat On

O (green)

Reversing Valve Energized, unit is in
cooling mode

Y2 (green)

Second Stage Compressor On

Y1 (green)

First Stage Compressor On

G (green)

Fan On

Just above the connector block is a single red LED

labeled CFM that will blink intermittently when the
unit is running and may flicker when the unit is off.

This LED indicates the air delivery of the blower at
any given time. Each blink of the LED represent 100

CFM of air delivery so if the LED blinks 12 times,

pauses, blinks 12 times, etc. the blower is delivering

1200 CFM. Refer to Figure #7 for factory

programmed air delivery settings for the TA Series.

To the right of the thermostat connection block is a
green LED labeled dehumidify.
Just above and to the right of the thermostat
connection block are four sets of jumper pins labeled
ADJ, DELAY, HEAT and COOL. The ADJ set of pins are
labeled NORM, (+), (-) and TEST. TA units will all be set
on the NORM position from the factory, however,

airflow can be increased (+) or decreased (-) by 15%

from the pre-programmed setting by relocating the
jumper in this section. The TEST position is used to
verify proper motor operation. If a motor problem is
suspected, move the ADJ jumper to the TEST position
and energize G on the thermostat connection block. If
the motor ramps up to 100% power, then the motor
itself is functioning normally. Always remember to
replace the jumper to NORM, (+) or (-) after testing and
reset the unit thermostat to restore normal operation.

Caution

Do not set the ADJ jumper to the (-) setting
when electric heaters are installed. Doing so
may cause the heaters to cycle on their
thermal overload switches, potentially
shortening the life of the switches.

The other three sets of jumper pins are used to
select the proper program in the ECM motor for the

unit. Refer to Figure #7 for the proper jumper

placement.

Caution

Always disconnect power before changing
jumper positions on the interface board and
reset the unit afterward.

To the left of the red and green status LED’s is a row
of 1/4” male quick connects. These are used to pass
thermostat inputs on to the rest of the control
circuit. Remember to always turn off unit power at
the circuit breaker before attaching or disconnecting

Motor Profile Air Flow Table

Figure 7: Motor Profile Air Flow Table CFM

Two Stage Units

Model

fan

only

Cool/

HeAT

Cool/

HeAT

AuX

HeAT