HVAC companies live between two systems that never talk to each other. The office runs quotations, purchase and invoicing somewhere; the field runs on WhatsApp, printed job sheets and a technician's memory of which compressor was replaced on which rooftop unit last summer. The result is familiar: AMC contracts that quietly expire because nobody was watching the renewal date, second visits because the van did not carry the right TXV or filter drier, warranty claims that fail because the serial number was never captured, and month-end invoicing that reconstructs three weeks of work from photographs of paper. ERPNext gives you a genuinely strong commercial and stock backbone — Customer, Item, Serial No, Warehouse, Stock Entry, Sales Order, Sales Invoice, Timesheet and the Maintenance module — but it stops short of field service. There is no dispatch board that shows today's technician load, no job card that a technician completes on a phone with parts, labour hours and a customer signature, no AMC object that knows how many of its scheduled visits remain, and no concept of a van as stock that depletes as jobs are closed.

This is a proper Frappe application — its own app on the bench, its own module, installed alongside erpnext, never a pile of Custom Fields bolted onto core DocTypes. The core objects are HVAC Job Card (customer, site, equipment, fault, assigned technician, scheduled window, status workflow), HVAC Service Contract for AMCs (billing terms, covered equipment, visit entitlement, start/end dates), HVAC Contract Visit as the scheduled child occurrences generated from the contract's frequency, and HVAC Equipment — one record per installed unit, keyed to the ERPNext Serial No where you track serials, carrying make, model, tonnage, refrigerant type, commissioning date, warranty expiry and its site location. Every job card, part consumed and reading taken links back to that equipment record, so a technician standing on a roof can open one document and see everything ever done to that unit.

The mechanics are standard Frappe, which is deliberate — it means your own team can maintain it. Dispatch and status transitions run through a Frappe Workflow with role-gated actions, so a technician can move a card from Assigned to In Progress to Completed but only a Service Manager can reopen or cancel one. hooks.py doc events do the wiring: on job card submit, a Stock Entry of type Material Issue moves consumed parts out of the technician's van warehouse; billable labour hours post to a Timesheet linked to the Project or Sales Order; a completed non-contract job card assembles a Sales Invoice draft with parts at their selling rate and labour at the rate card, ready for the office to review and submit. A scheduler_events daily job generates upcoming Contract Visits from each active AMC's frequency, flags contracts inside the renewal window and creates a renewal Opportunity so nobody has to remember. Van stock is not a custom table — each service vehicle is a real ERPNext Warehouse under a Vans parent, replenished with Material Transfer from the main store, so your stock ledger, valuation and reorder levels stay correct and a van is auditable like any other location. Whitelisted methods exposed over the Frappe REST API return a technician's day, accept job card completion with parts, hours, meter readings and a signature attachment, and are permission-checked per user; client scripts keep the desk forms fast, filtering the equipment link to the selected customer's site and warning before you consume a part the van does not hold. Role profiles ship for Technician, Dispatcher, Service Manager and Accounts, with User Permissions so a technician sees only their own assignments. We target Frappe/ERPNext v15 and v16 and build against the exact version you run.

This is build-to-order, not a marketplace download. There is no instant-download button on this page, because there is no shrink-wrapped archive waiting behind it — an HVAC service business in Dubai running annual AMCs on chiller plant needs a different contract model from a residential split-unit installer in Karachi billing per call-out. You request a quotation, we run a scoping call, and we write down exactly which DocTypes, workflow states, invoicing rules and reports you are buying before anyone writes code. Typical delivery is 2–4 weeks from confirmed scope. We build on a staging copy of your site, you run UAT against your own customers and equipment, then we install on production with a tested rollback, hand over the git repository and source, train your dispatchers and technicians, and stay on support through the post-go-live window.