An HVAC company sells three things at once: an installation project, a maintenance contract, and the parts and labour that keep the equipment running. Dynamics 365 Business Central handles the money side of all three well — sales quotes, jobs, service items, service contracts, item ledger — but it was never designed around the day a service manager actually works. There is no dispatch board showing which technician is where, no job card a technician can complete on a phone, no AMC renewal pipeline that warns you ninety days out, and no clean way to treat a van as a stock location that consumes parts against a specific service order line. Most HVAC firms bridge those gaps with a whiteboard, a WhatsApp group and a spreadsheet of contract expiry dates — and the reconciliation back into Business Central happens weeks later, if at all.

We build an AL extension that closes that gap inside your own Business Central tenant rather than beside it. The core is a Service Job Card table backed by table extensions on Service Header, Service Line, Service Item and Service Contract Header, so every job card resolves to real Business Central documents and posts through the standard service posting routines — no shadow ledger, no month-end reconciliation. A dispatch board page assigns jobs to technician resources against Resource Capacity, respects skill and certification codes, and writes back planned start and end times so Resource Ledger Entry reflects actual field time. AMC contracts extend the native Service Contract with renewal windows, escalation percentages and visit schedules; a job queue entry generates the next period's planned service orders and flags contracts approaching expiry into a renewal worklist. Van stock is modelled as per-technician locations fed by transfer orders from the main warehouse, so a part consumed on a job card decrements the technician's bin and lands on the invoice line in one step.

Technically it is a clean AL extension for current Business Central release waves, SaaS or on-premises. Business logic lives in codeunits invoked through event subscribers on the standard service and inventory publishers, so upgrades do not fight your customisations. Equipment history is exposed as a FactBox on Service Item — every past visit, part replaced, refrigerant charge and warranty state on one page. API pages published on REST API v2.0 / OData v4 expose job cards, technician schedules and equipment history for a mobile app, a customer portal, or a Power Apps canvas app over Dataverse; Power Automate flows can fire on job completion to notify a customer. Dedicated permission sets separate Dispatcher, Technician, Service Manager and Accounts roles, so a technician can close a job card without touching pricing.

Delivery is build-to-order. After a scoping call we write a specification covering your job card fields, AMC billing pattern, van stock policy and the quotation-to-invoice flow you actually use, then build against a sandbox of your tenant. Typical delivery is one working week from confirmed scope, depending on how much of the mobile and Power Platform surface you want in the first release. You get the installable extension for your Business Central version, UAT on staging before anything touches production, and the source in a git repository you own.