Nest 'Delayed' message — Power-sharing (no C wire) problem

What this error means

Nest shows 'Delayed for X min' when it can't draw enough consistent power. Without a C (common) wire, the Nest 'power-steals' from the heating/cooling circuits; when its battery runs low it delays calls for heat/cool to recharge — which reads as the office HVAC randomly ignoring the thermostat.

Symptoms

• 'Delayed' or 'Starts in X min' on screen
• HVAC turns on late or short-cycles
• Thermostat battery level drops in settings

Try this first (safe DIY steps)

1. Check Settings → Technical Info → Power for battery voltage (community-reported threshold: below ~3.6V the thermostat starts shedding features and delaying calls)
2. The durable fix is adding a C wire or Google's Nest Power Connector at the air handler — a straightforward job for an HVAC tech or handy facilities person
3. As a stopgap, most Nest models can be USB-charged to revive the battery (officially supported; note the 2020 Nest Thermostat has no USB port) — but this treats the symptom, not the power-delivery problem

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

Have a tech add the C wire/adapter — under an hour of work and it permanently ends the delays.