Lennox Heat Pump Error Code Simultaneous SLOW Flash

The Simultaneous SLOW Flash pattern means the system is operating normally or is in standby mode. Both diagnostic LEDs flashing slowly together is the control board's way of indicating that no faults are detected and everything is functioning as expected. No service or repair is needed.

No, this indicator presents no safety concern. It confirms the control board is powered and functioning correctly. If you have unrelated concerns about system performance, unusual noises, or ice buildup, those should be evaluated separately by a qualified technician.

There is no cost associated with this indicator because it signals normal operation rather than a fault. If a technician visit is scheduled based on this LED pattern alone, the visit will confirm the system is working correctly. If other performance issues are present, diagnostic service calls typically range from $75 to $150 depending on your region and provider.

No action is required. This pattern is a positive status indicator, not an error code. If the system is not heating or cooling your space effectively despite showing this status, the underlying issue could be a thermostat setting, a dirty filter, or a refrigerant concern, none of which are signaled by this LED pattern itself.

A reset is not needed and will not change anything meaningful since this is a normal operating status. Power-cycling the unit will simply result in the same slow simultaneous flash pattern appearing again once the control board completes its startup sequence.