Short answerA general home inspection confirms the furnace, air conditioner and water heater turn on. A dedicated pre-purchase HVAC inspection goes further: heat exchanger inspection, combustion analysis, refrigerant pressures, duct condition, age verification and remaining life estimates. In Washtenaw County, where many homes carry 15-to-25-year-old equipment, it is one of the cheapest ways to avoid a mid-four-figure surprise in your first winter.
What the general home inspector does and does not do
Michigan does not license home inspectors, and the standards of practice most of them follow (ASHI or InterNACHI) explicitly limit the HVAC portion to operating the equipment with normal controls and reporting visible defects. In a typical Ann Arbor or Ypsilanti inspection that means the inspector sets the thermostat up, confirms warm air comes out of a register, sets it down, confirms the condenser kicks on if it is above about 60 degrees outside, notes the age from the data plate, and moves on. They are not permitted by their own standards to remove the burner compartment cover and look at the heat exchanger, to put gauges on the refrigerant lines, or to run a combustion analyzer.
That is not a knock on inspectors. They are covering a whole house in three hours. But it means the two most expensive systems in the home get a five-minute functional test, and the failures that cost the most, a cracked heat exchanger or a compressor pulling high amps, are invisible to that test. We have been called to homes in Pittsfield Township and Superior Township within weeks of closing where the furnace "passed" and had a heat exchanger crack you could see with a flashlight once the cover was off.
What a dedicated HVAC inspection covers
Our new-home HVAC inspection takes about 60 to 90 minutes depending on the equipment, and it is scheduled during the inspection contingency window, usually alongside or just after the general inspection.
- Furnace. Model and serial number decoded for the actual manufacture date, which is often a few years older than the seller's disclosure says. Burner compartment opened; heat exchanger inspected visually and with a scope where the design allows it. Combustion analysis on the flue gases to measure CO, oxygen and efficiency. Flame sensor, ignitor, inducer motor, pressure switch and blower motor checked for condition and amp draw. Flue and venting inspected for proper pitch, material and connections; on a 90-percent furnace, the PVC intake and exhaust terminations outside and the condensate drain and trap.
- Air conditioner. Refrigerant type and pressures, superheat or subcooling against the manufacturer's chart, compressor and fan amp draws, capacitor microfarads, contactor condition, condenser coil cleanliness, line set insulation, and evaporator coil condition if it is accessible. On R-22 equipment, we note that a recharge after any leak is going to be expensive.
- Water heater. Age, tank condition, signs of rust or weeping at the fittings, TPR valve and discharge pipe, burner and flue draft on an atmospheric unit, and whether there is a drain pan where one is needed.
- Ductwork. Supply and return trunk condition, visible leaks at joints and takeoffs, whether the returns are adequate for the house, flex duct condition and any crushed or disconnected runs in the basement or crawlspace.
- Thermostat, humidifier and filtration. Type and function; whether the humidifier drain and solenoid work; filter size and how the cabinet is set up.
You get a written report with photos, the age of each piece of equipment, what is working, what is marginal, what is failed, and a plain estimate of remaining service life.
Why this matters more in Washtenaw County than most places
The housing stock here skews old and the climate is hard on equipment. Pre-war two-stories in the Old West Side of Ann Arbor and the Normal Park area of Ypsilanti often have furnaces that were replaced once in the 1990s and never since. The big 1950s to 70s ranch and colonial inventory in Ypsilanti Township and across the county line in Westland and Garden City is full of 80-percent furnaces on their second or third decade. Even the 1990s and 2000s subdivisions in Canton, Saline and Pittsfield are now 20 to 30 years old, and builder-grade equipment from that era is at or past its design life.
Then there is the winter. Six thousand-plus heating degree days a year and the occasional polar vortex week means a furnace that is marginal in October is a no-heat call in January, and the no-heat call usually comes at 2 a.m. on the coldest night. A buyer who moves in during August has no way to know the furnace is marginal unless someone looked.
How to use the findings in the deal
The report gives you three things to work with. First, leverage. A furnace at year 24 with a cracked heat exchanger is a documented safety defect, and a seller or their agent cannot reasonably argue it is normal wear. A compressor at year 18 drawing amps above its rating is a documented near-term expense. Buyers in this market have used our reports to negotiate a credit at closing, to get a seller-paid replacement before close, or simply to go in with eyes open and budget for the replacement in year one.
Second, priorities. Not everything on a report is urgent. We separate "fix before you move in" from "plan for within two years" from "cosmetic." A 12-year-old AC with a weak capacitor is a quick repair, not a reason to walk away.
Third, a baseline. If you buy the house, you now have a dated record of the equipment's condition, which is useful when something fails later and you are deciding whether to repair or replace.
What we tell buyers about sellers' disclosures
Michigan's Seller Disclosure Statement asks the seller to mark whether the heating and cooling systems are in working order, and most sellers honestly check yes because the furnace runs. "Working order" is not the same as "sound." A furnace with a heat exchanger crack usually still produces heat; the problem is what else it produces. See carbon monoxide and furnace safety for why that distinction matters. We also see "new furnace" on listings where the furnace is a 2009 model, which is new relative to the 1978 one it replaced but is not new.
Ages matter for refrigerant too. If the AC is pre-2010 it is almost certainly R-22, and the R-22 phase-out changes the economics of any future leak repair.
Timing and logistics
Inspection contingencies in Washtenaw County contracts commonly run 7 to 10 days. We schedule within that window, often same-week, and we coordinate with the listing agent for access the same way the general inspector does. We need the gas and electric on and, for a meaningful AC test, an outdoor temperature above about 60 degrees. In a winter purchase we can still inspect the condenser electrically and visually and note what we could not test. The buyer or their agent is welcome to be there, and most are; it is a good hour to learn how the house's systems work before you own them.
If you are buying in Ann Arbor, Ypsilanti, Saline, Canton or anywhere within our 20-mile radius, call us as soon as your offer is accepted so the inspection lands inside the contingency, not after it.