What do the 24 Volt Deluxe control error codes mean?

Check output voltage at controls transformer is supplying 24-27vac.

Check if the controls transformer circuit breaker is tripped. 

Check to see if the customer has a fire alarm wired on the secondary side of the controls transformer preventing operation: How do you wire a fire alarm to a WSHP with Deluxe Controls?

Check high voltage supplying the controls transformer is within +/- 10% of the unit rating. 

The event may be normal and informational only. Observe compressor operation and if you notice the compressor running short cycles (3 min on / 3 min off) consider the following:

If the thermostat sits near a drafty window, a heat-generating appliance, direct sunlight, or a supply air register, it reads the local temperature inaccurately and shuts the HVAC system down prematurely. See your unit IOM for suggestions on locating the thermostat. 

Most conventional thermostats let you adjust the "swing" or "deadband" (how much the room temperature must drift from the setpoint before the system turns on). If the swing is set too tight (e.g., 0.5°F or 1°F), the system may shut off too soon. 

Check to see if other HVAC systems may be serving the same space and providing excess capacity. Consider offsetting temperature setpoints or turning a system off using a lead lag controller. 

Check overall system operations to ensure charge, airflow and water flow are correct. 

Use the Operating Pressures tables provided in the unit IOM as a benchmark of normal operation. See Refrigeration Malfunction System Troubleshooting for additional information. 

The brown-out protection function measures the input voltage to the controller and halts the compressor operation. 

Once a brown-out situation has occurred, the anti-short cycle timer will become energized. 

The general fault contact will not be affected by this condition. 

The voltage will continue to be monitored until the voltage increases. The compressors will be enabled at this time if all start-up time delays have expired, and all safeties have been satisfied.

Test the high voltage incoming to the controls transformer is within +/- 10% of the unit rating. 

Verify the output of the controls transformer is supplying 24-27vac. If less than 24, check the transformer tapping on the line side vs the wiring diagram supplied on the side of the transformer. Many control transformers are designed to work with different high voltage sources, and incorrect wiring on the line side may result in a voltage drop on the secondary / control side of the transformer. 

The low-pressure switch is set to open at refrigerant suction pressures of 40 psig in most applications. 

If the switch is open for 45 seconds during compressor start, which suspends compressor operation.

Upon the low-pressure switch closing with an active cooling call (24-27vac present at the Y input), the control shall go into soft lockout mode initializing a three-minute time delay and a random start of 3 to 10 second time delays. 

Once these delays have expired, the unit will be allowed to run. 

Check overall system operations to ensure charge, airflow and water flow are correct. 

Use the Operating Pressures tables provided in the unit IOM as a benchmark of normal operation. See Refrigeration Malfunction System Troubleshooting for additional information. 

In a high-pressure situation, the high-pressure switch opens due to excessive discharge pressures in excess of 600 psig. The compressor contactor is de-energized, which suspends compressor operation. The control will go into soft lockout mode until the high-pressure switch closes. 

Upon the high-pressure switch closing with an active cooling call (24-27vac present at the Y input), the control shall initializing a three-minute time delay and a random start of 3 to 10 second time delays. 

Once these delays have expired, the unit will be allowed to run. 

Check overall system operations to ensure charge, airflow and water flow are correct. 

Use the Operating Pressures tables provided in the unit IOM as a benchmark of normal operation. See Refrigeration Malfunction System Troubleshooting for additional information. 

If the low-pressure situation
occurs again within 30 minutes of a Soft Lockout (low pressure), and the device is open for more than 45 seconds, the control will be placed into a manual lockout mode and halt compressor operation.

Power must be cycled on the control before it will resume compressor operation.

Check overall system operations to ensure charge, airflow and water flow are correct. 

Use the Operating Pressures tables provided in the unit IOM as a benchmark of normal operation. See Refrigeration Malfunction System Troubleshooting for additional information. 

If a high-pressure situation occurs within one hour of the Soft Lockout (high pressure), the control will be placed into a manual lockout mode and halting compressor operation. 

Power must be cycled on the control before it will resume compressor operation.

Check overall system operations to ensure charge, airflow and water flow are correct. 

Use the Operating Pressures tables provided in the unit IOM as a benchmark of normal operation. See Refrigeration Malfunction System Troubleshooting for additional information. 

The compressor disable relay provides a temporary disable in compressor operation. 

The signal would be provided from a water loop controller in the system. It would disable the compressor because of low water flow, peak limiting or if the unit goes into an unoccupied state. 

Once the compressor has been disabled, the anti-short cycle time period will begin. 

Once the compressor disable signal is no longer present, and all safeties are satisfied, the control will allow the compressor to restart.

Locate inputs labeled CD1 and CD2 of the Deluxe control and verify the contacts are open. Remove the plug from the board and test continuity on the wires. 

Field controls are commonly wired here.