A standard San Diego home inspector spends 5 to 10 minutes on the AC. They turn it on, feel the supply air, glance at the condenser, note the age, and move on. That’s not an HVAC inspection. It’s a function check. In a county where the median home price sits north of $900,000 and AC condition routinely becomes a closing-credit fight, the gap between those two things can run $4,000 to $15,000.
A separate pre-purchase HVAC inspection from a licensed contractor runs $175 to $400 in San Diego and catches things the general home inspector physically can’t see in their window.
What the home inspector actually checks
Standard San Diego home inspections (typically $400 to $700 for a 1,500 to 2,500 sq ft home) include AC under a “major systems” walkthrough. Per ASHI and InterNACHI standards, the inspector will:
- Turn the system on at the thermostat and confirm it cools
- Measure the temperature split between supply and return (15 to 20 degrees is the rule of thumb)
- Note the system age from the data plate
- Check that the condenser is level and not blocked
- Look at visible duct condition in the attic
- Confirm the disconnect is present and accessible
That’s it. They don’t pull panels, hook up refrigerant gauges, test capacitor microfarads, scope the evap coil, or pressure-test the duct system. Most won’t even run the heat if it’s a warm day, and they explicitly disclaim refrigerant, electrical components inside the unit, and anything requiring tools beyond a thermometer.
What a 10-minute AC check misses
This is where San Diego buyers get burned. The system can pass a home inspection and still have any of the following waiting to surface in year one of ownership.
1. Slow refrigerant leaks
A leak losing half a pound of refrigerant per month won’t show in 10 minutes of runtime. The split looks fine. The system cools the house. Then summer hits, demand goes up, and by August the unit can’t keep up. By the time it’s diagnosed, the homeowner is paying for either repeated charges ($350 to $600 each) or a leak search ($300 to $500) followed by a coil replacement ($1,800 to $3,500) or full system replacement.
An HVAC inspector hooks up gauges, reads superheat and subcooling, and can flag a system running outside spec. They can also UV-dye or sniff-test for active leaks at the coil and line set.
2. Failing capacitors
Capacitors are $15 to $30 parts that fail in 5 to 8 years in San Diego (faster in inland heat zones like El Cajon, Santee, Escondido). A weak capacitor still starts the system. It just won’t last another summer. A real inspector measures microfarads against the rating stamped on the cap. Anything more than 6% below rated capacity is end-of-life.
Home inspectors don’t open the access panel. Capacitor weakness shows up as a no-cool call in July, when every HVAC company in the county is two weeks out.
3. Hidden duct leaks
San Diego’s older housing stock (1950s to 1970s tract homes in Clairemont, La Mesa, Linda Vista, North Park) often has original metal ductwork with failed mastic at the joints, crushed runs in tight attic spaces, and disconnected boots in vaulted ceilings. California Title 24 requires duct sealing to under 6% leakage on system replacements, but existing ducts in resale homes routinely test at 25 to 40% leakage.
A home inspector eyeballs visible duct from the attic hatch. An HVAC inspector can run a duct blaster test ($250 to $400 add-on) or at minimum do a smoke test at the registers to spot major losses.
4. Undersized or oversized systems
A 2,400 sq ft home in Poway with a 2-ton system is undersized. A 1,200 sq ft beach bungalow in Mission Beach with a 4-ton system is oversized (and will short-cycle, run humid, and fail early). Home inspectors don’t run Manual J load calculations. They just note the tonnage.
If the listing claims “newer AC” but the load doesn’t match the house, the buyer inherits either ongoing comfort complaints or premature equipment death.
5. R-22 systems still in service
Federal R-22 production stopped January 2020. Systems made before 2010 typically run R-22. As of 2026, recovered R-22 refrigerant runs $130 to $250 per pound, and a recharge often hits $700 to $1,400 on a leaking system. The system itself isn’t illegal to operate, but it’s economically dead. Any leak triggers a replacement decision, not a repair.
Buyers picking up homes built before 2010 in established neighborhoods (Kensington, Talmadge, San Carlos, parts of Bonita) should specifically ask whether the AC is R-22 or R-410A. An inspector reads the data plate; an HVAC inspector confirms it and assesses replacement urgency.
6. Hidden mold in the evaporator coil
San Diego’s marine layer keeps coastal homes (Pacific Beach, Ocean Beach, Encinitas, Carlsbad) at high indoor humidity in shoulder seasons. Evap coils that don’t drain properly grow mold inside the air handler, which the homeowner inhales every time the blower runs.
You don’t see this from a thermostat. An HVAC inspector pulls the blower panel and looks. Remediation runs $400 to $1,200 (coil cleaning, drain line, UV light install).
7. Electrical problems at the disconnect
Salt-air corrosion on coastal disconnects (anything within ~2 miles of the ocean) is universal in San Diego. The home inspector confirms the disconnect exists. The HVAC inspector pulls the pullout, checks for pitting, burnt contacts, and undersized wiring from a previous upgrade. A failed disconnect can cause repeated nuisance trips or, worst case, an electrical fire.
What a real pre-purchase HVAC inspection covers
Expect a 60 to 90 minute visit covering:
- Refrigerant charge verified by gauges (superheat and subcooling)
- Capacitor microfarad reading on compressor and fan motor
- Contactor pitting and condition
- Static pressure across the air handler (high static means restricted ducts or filter, or oversized equipment)
- Temperature split, supply and return
- Blower motor amp draw vs rated
- Visible coil inspection (evap and condenser)
- Drain line and pan condition
- Refrigerant type confirmed (R-22 vs R-410A vs R-454B)
- Filter type, size, and last change
- Duct visual and at least one register check
- Thermostat compatibility and wiring
- Age and remaining expected service life estimate
- Heating function check on the same visit (since the tech is already there)
You’ll get a written report. The good ones include photos and a repair-cost or replacement-cost estimate range so you can take it back to the seller for a credit request.
Pre-purchase HVAC inspection cost in San Diego
| Scope | Typical cost |
|---|---|
| Basic HVAC inspection (single system, no duct test) | $175 to $250 |
| Standard inspection plus written report | $250 to $325 |
| Inspection plus duct leakage test | $400 to $550 |
| Two-system home (AC plus separate furnace) | $325 to $475 |
| Multi-zone or mini-split system | $300 to $450 |
Some San Diego HVAC companies waive or credit the inspection fee if you book repair or replacement with them post-close. Ask up front.
When to ask for a seller credit, and how much
Use this framework after the inspection comes back.
| Finding | Reasonable credit ask |
|---|---|
| System over 15 years old, still functional | $3,000 to $8,000 (partial replacement credit) |
| R-22 system, any age | $5,000 to $10,000 (functionally end-of-life) |
| Active refrigerant leak | $1,800 to $4,000 (repair or coil replacement) |
| Failed or near-failed capacitor | $150 to $400 |
| Duct leakage over 20% | $1,500 to $3,500 (seal or partial replace) |
| Mold in evap coil | $500 to $1,500 |
| Salt-air corrosion on coastal disconnect | $300 to $800 |
| Oversized or undersized system | Document for future replacement; rarely a closing credit |
Sellers in soft markets (which San Diego has trended toward in 2025 and 2026 outside the under-$1M range) will often credit rather than re-list. In hot markets, expect more pushback. Either way, a documented HVAC report from a licensed contractor carries more weight than a line item in the general inspection report.
When the inspection isn’t worth it
Skip the separate HVAC inspection if:
- The home has a documented full HVAC replacement in the last 3 years with current warranty and maintenance records
- You’re already planning a full HVAC replacement post-close as part of a renovation (you don’t need to know what’s failing, you’re replacing it)
- The home is a teardown or major remodel
For everything else, especially anything 8+ years old or coastal, it’s $200 to $400 against a five-figure risk. The math is straightforward.
San Diego scenarios where this paid off
A 1968 ranch in Allied Gardens listed at $1.05M had a “working” AC per the home inspection report. The HVAC inspection found R-22, low charge, and a 22-year-old condenser. Seller credit: $7,500. Replacement quoted at $9,400; buyer covered the gap.
A 2003 Mira Mesa two-story listed at $985K passed home inspection. HVAC inspection caught a 14 microfarad reading on a 45/5 dual-run capacitor (compressor side at 31% below rated). Cost to fix: $285. Without it, the buyer would have eaten a July emergency call.
A 1958 Mission Hills bungalow had original ductwork. Duct blaster test showed 38% leakage. Seller credit: $2,800 toward duct sealing. Energy bill drop after the work was real and measurable.
FAQs
Is a separate HVAC inspection required when buying a home in San Diego? No. It’s not required by lender, escrow, or by California law. It’s a buyer-discretion add-on. For systems older than 8 years, in coastal corrosion zones, or in homes where the seller can’t produce maintenance records, it’s usually worth the cost.
Can my home inspector do the HVAC inspection too? Most home inspectors will check function and note age, but they’re not licensed HVAC contractors and won’t pull panels, hook up refrigerant gauges, or do load calculations. The scope and the tools are different. Use a licensed HVAC contractor for the HVAC piece.
When should I schedule the HVAC inspection during the buying process? During the inspection contingency period, after the general home inspection turns up anything that suggests deeper investigation (age over 10 years, water staining, unusual noises noted, mismatched equipment ages). You typically have 7 to 17 days in California purchase contracts to complete inspections.
Should I get the AC inspected even if I’m buying in winter? Yes. A licensed HVAC tech can run the system briefly in winter without damaging it, check refrigerant charge, check capacitors, and verify the unit’s condition. The standard “don’t run AC below 60 degrees” rule is for prolonged operation, not a 15-minute diagnostic.
How long does a pre-purchase HVAC inspection take? 60 to 90 minutes for a single-system home. Add 30 to 45 minutes for a duct leakage test or a second system. The report typically arrives within 24 to 48 hours.
What if the seller refuses to credit a documented HVAC issue? You have three options: walk (your inspection contingency protects your deposit), negotiate a price reduction in lieu of credit, or close as-is and budget the repair. The documented report from a licensed contractor strengthens any of these positions and gives you a defensible record if anything fails post-close.
If you’re under contract on a San Diego home and need an HVAC inspection during your contingency window, check our HVAC repair pricing for context on what fixes typically cost, or read up on the 5,000 rule for repair-vs-replace decisions. To book an inspection on your timeline, call our team for a same-week appointment.