General Assist Technical Reference
Danfoss Controller - Airstage RTPU
Service access and compressor delay settings
For commissioning, diagnostics and supervised service of Airstage rooftop package units
This procedure provides the Danfoss controller service-menu password and explains the Carter Oil Timer and Blackout Setting. These settings control compressor start delays after power-up or a supply interruption.
Qualified personnel only: Compressor protection delays must not be bypassed unless oil temperature and operating conditions have been verified. Incorrect adjustment can result in liquid refrigerant migration, poor lubrication and compressor damage.
1. Accessing the service menu
| Item | Details |
|---|---|
| Menu path | Main Menu → Settings → Service Menu |
| Service password | 5653 |
Note: Menu wording may vary slightly by controller software revision. Record the original value before changing any parameter.
2. Carter Oil Timer
The Carter Oil Timer provides a delay after power is applied or following a prolonged shutdown. The delay allows compressor oil and refrigerant conditions to stabilise before compressor operation.
Temporary service adjustment
- Confirm the compressor sump heater has been operating and the oil sump temperature is above 15°C.
- Open the Service Menu using password 5653.
- Locate Carter Oil Timer.
- Record the existing value.
- Reduce the delay only for the supervised test. Where required, set the delay to approximately 0-30 seconds.
- Complete the required commissioning or diagnostic checks.
Do not bypass the oil delay when the unit has been unpowered for an extended period, the sump heater has not been operating, or oil temperature has not been confirmed.
3. Blackout Setting
The Blackout Setting controls the restart delay applied after a power failure or supply interruption. It prevents an immediate compressor restart when safe lubrication conditions may not yet be established.
Temporary service adjustment
- Confirm the sump heaters have been energised and oil temperature is suitable for compressor operation.
- Open the Service Menu using password 5653.
- Locate Blackout Setting.
- Record the existing value.
- Temporarily reduce the restart delay to support supervised commissioning or testing.
- Observe compressor start-up and confirm normal current, pressure and sound.
4. Restore the protection settings
After service testing is complete:
- Return the Carter Oil Timer to its original or factory value.
- Return the Blackout Setting to its original or factory value.
- Exit the Service Menu and verify the settings remain saved.
- Record all temporary changes and restored values in the service report.
5. Quick reference
| Function | Purpose | Service use |
|---|---|---|
| Service Menu | Unlocks technician-level settings | Password 5653 |
| Carter Oil Timer | Delays compressor start after power-up or long shutdown | Temporarily reduce only after confirming oil conditions |
| Blackout Setting | Controls restart delay after supply interruption | Temporarily reduce for supervised testing when heaters are active |
Important: These adjustments are temporary service tools and are not a substitute for confirming compressor oil temperature, sump-heater operation and correct system conditions.