Bosch CE025, Installation And Maintenance Manual

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Subject to change without prior notice                                      Revised 05-12

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CE Series

TroublesHooTInG

Problem

Possible Cause

Checks and Corrections

Entire unit 

does not run

Power Supply Off

Apply power, close disconnect

Blown Fuse

Replace fuse or reset circuit breaker. Check for correct fuses

Voltage Supply Low

If voltage is below minimum voltage specified on unit data plate, 

contact local power company.

Thermostat

Set the fan to “ON”, the fan should run. Set thermostat to “COOL” and 

lowest temperature setting, the unit should run in the cooling mode 

(reversing valve energized). Set unit to “HEAT” and the highest tempera-

ture setting, the unit should run in the heating mode. If neither the blower 

or compressor run in all three cases, the thermostat could be miswired or 

faulty.To ensure miswired or faulty thermostat verify 24 volts is available 

on the condensing section low voltage terminal strip between “R” and 

“C”, “Y” and “C”, and “O” and “C”. If the blower does not operate, verify 

24 volts between terminals “G” and “C” in the air handler. Replace the 

thermostat if defective.

Blower 

operates but 

compressor 

does not

Thermostat

Check setting, calibration, and wiring

Wiring

Check for loose or broken wires at compressor, capacitor, or contactor.

Safety Controls

Check UPM board red default L.E.D. for Blink Code

Compressor  

overload open

If the compressor is cool and the overload will not reset, replace compressor.

Compressor motor 

grounded

Internal winding grounded to the compressor shell. Replace compressor. 

If compressor burnout, install suction filter dryer.

Compressor  

windings Open

After compressor has cooled, check continuity of the compressor 

windings. If the windings are open, replace the compressor

Unit off on 

high pressure 

control

Discharge pressure 

too high

In “COOLING” mode: Lack of or inadequate water flow. Entering water 

temperature is too warm. Scaled or plugged condenser.

In “HEATING” mode: Lack of or inadequate air flow. Blower inoperative, 

clogged filter or restrictions in duct work

Refrigerant charge

The unit is overcharged with refrigerant. Reclaim refrigerant, evacuate 

and recharge with factor recommended charge.

High pressure

Check for defective or improperly calibrated high pressure switch.

Unit off on 

low pressure 

control

Suction pressure 

too low

In “COOLING” mode: Lack of or inadequate air flow. Entering 

air temperature is too cold. Blower inoperative, clogged filter or 

restrictions in duct work

In “HEATING” mode: Lack of or inadequate water flow. Entering water 

temperature is too cold. Scaled or plugged condenser.

Refrigerant charge

The unit is low on refrigerant. Check for refrigerant leak, repair, 

evacuate and recharge with factory recommended charge.

Low pressure 

switch

Check for defective or improperly calibrated low pressure switch.

Unit short 

cycles

Unit oversized

Recalculate heating and or cooling loads.

Thermostat

Thermostat installed near a supply air grill; relocate thermostat. 

Readjust heat anticipator.

Wiring and controls Check for defective or improperly calibrated low pressure switch.

Troubleshooting