Emerson Liebert MC Microchannel Outdoor Condenser 28 - 220kW User Manual

Condenser will not start

No power to condenser.

Check voltage at input terminal block.

Circuit breaker or fuse for low-voltage 

transformer in condenser is tripped.

Locate problem in condenser electrical panel and 

repair.

No low-voltage signal to/from indoor 

unit.

Locate open circuit and repair.

Low discharge pressure

Faulty head pressure control valve or 

condenser control board (PEC/BEC).

Replace if defective.

High discharge pressure

Dirty condenser fins.

Clean coil.

Condenser fans not operating.

Check for low-voltage signal from indoor unit.
Check fan motors and fuses.

High refrigerant charge

Check refrigerant charge.

SPD green and red LEDs 

are extinguished 

No voltage or improper phasing exists 

at condenser.

Check voltage at input terminal block.

Electrical connections to SPD are faulty.

Locate connection problem and repair.

Condenser disconnect is turned Off.

Recheck lights with disconnect switch in the On 

position.

SPD red LED is 

illuminated 

A surge exceeding the rating of the SPD 

has occurred.

Replace SPD and inspect other components for 

damage and replace them if necessary.

Control Board LEDs do 

not light.

Connection to P24 is loose or 

disconnected.

Check the connection to P24 to verify that is 

connected securely.
Check the connector from the transformer for loose 

terminals.

Fuse located next to P24 has blown.

Verify that the fuses next to P24 have not blown. 

Replace as needed.

24V transformer has failed.

With a voltmeter verify that the output from the 

transformer is 24Vac ±10%. If the value exceeds 
±

10%, verify that the correct primary leads are 

being used.

Control Board (PEC/BEC) has failed.

If there is no output voltage, verify that the primary 

connections are secure and receiving the correct 

voltage. If they are, replace the transformer.

Fan will not run

Jumper not installed between 24V and 

DIN1 (for Ziehl-Abegg fan motor).

Install jumper between 24V and DIN1 (for Ziehl 

Abegg fan motor).