n8n HVAC Maintenance Reminder Workflow: Sheets & Gmail

Never miss the next HVAC service date—automate reminders with n8n, Google Sheets, and Gmail

This n8n HVAC Maintenance Reminder Workflow: Sheets & Gmail turns every newly submitted maintenance agreement into tracked data and automatic outreach—so customers get timely reminders and your office receives escalations when service dates are overdue.

What this workflow does

• Intake via webhook: Receives a new agreement through the “When Agreement Added” webhook (POST, path hvac-agreement-intake-0930).
• Normalize & validate: Builds a clean record (including auto-generated agreement_id in the format AG-yyyyMMdd-### when not supplied) and sets status to active. Any missing required fields (customer name, customer email, next due date, office email) are rejected by email rather than saved.
• AI-written welcome email: Uses gpt-6-luna to generate the agreement welcome email.
• Log to Google Sheets: Stores the agreement in the Agreements tab with key fields like last_service_date, next_due_date, agreement_end_date, office_email, and welcomed_at.
• Daily customer reminders: Every day at 07:00, checks for agreements due within 3 days or already overdue. Customers due soon get reminder emails; overdue items also trigger an escalation email to the office.
• Weekly AI review: Every Monday at 09:00, an AI review is sent to the office for the agreement book.

Use cases

• HVAC maintenance providers who want service-date compliance without manual follow-ups.
• Automation engineers building n8n workflows for intake → validation → sheet logging → scheduled email sequences.
• SaaS operators tracking agreements and ensuring reminders for upcoming and overdue maintenance.

Technical details

• n8n nodes: webhook, if, set, code, gmail, sticky note
• AI: gpt-6-luna for welcome email and weekly review
• Storage: Google Sheets (Agreements tab)

Last updated: October 2026.