A general inspector confirms the system turns on and blows hot or cold air. A real HVAC inspection goes further: correct sizing, ductwork and return air, refrigerant type, the condensate path, and whether past work was permitted. Knowing this before you close keeps a five-figure repair on the negotiating table instead of on your tab.
Before you buy: what to inspect
Equipment & performance
- Age of the furnace, AC, or heat pump and the date of last service
- Whether the system is sized to the home (a Manual J load calc) — bigger is not better
- Refrigerant type — older R-22 systems are increasingly expensive to service
- Even temperatures room to room (hot/cold spots point to duct or sizing issues)
- Unusual noises, short-cycling, or visible rust and scorching
Ducts, air & code
- Ductwork condition and sizing — crushed, disconnected, or undersized runs
- Adequate return air (too little starves the system and kills efficiency)
- Asbestos-wrapped ductwork, common in older Southern California homes
- A clear, properly routed condensate drain line
- Evidence the last changeout was permitted with HERS testing (required in CA)
Before you sell: California point-of-sale items
California requires certain items to be addressed when a home changes hands. Confirm the specifics with your agent and local jurisdiction.
What CA sellers should have ready
- Documentation that any AC/furnace changeout was permitted and HERS-tested
- A recently serviced, clean-running system (a tune-up before listing pays off)
- Disclosure of known issues — age, past repairs, or unpermitted work
Why a separate HVAC inspection is worth it
The standard home inspection underweights HVAC because it's built for breadth, not depth. Yet a replacement system is one of the most expensive purchases a home will ask of you. A focused HVAC inspection before closing tells you whether you're inheriting a healthy system or a near-term replacement.
Buying or selling with an aging HVAC system? Get it inspected first.
Frequently asked questions
Can a home inspector tell me if the AC is the right size?
Generally no — sizing requires a load calculation. A licensed HVAC technician can assess whether the system is appropriately sized, which affects comfort, bills, and lifespan.
Why does it matter if a past changeout was permitted?
In California, AC and furnace changeouts require a permit and usually HERS testing. Unpermitted work means charge and duct leakage went unverified — a common cause of poor performance — and it can complicate your resale later.
Is an older R-22 system a deal-breaker?
Not necessarily, but R-22 is phased out and costly to service, so factor a likely replacement into your offer. We can give you the numbers before you commit.
Keep exploring
Reviewed by John Stevenson Plumbing, Heating & Air. Based on how we evaluate residential HVAC (sizing, ductwork, return air, refrigerant, condensate, permit/HERS history) and California Title 24 changeout requirements. Confirm point-of-sale and permit specifics with your local building department. Last updated 2026-06-25.