The fall furnace tune-up is the single most important preventive service I offer. It's not glamorous, it doesn't feel urgent, and homeowners often ask me if it's really necessary. The answer is always yes — and after writing this post, I hope you'll understand why. In 8 years servicing DFW furnaces, every cracked heat exchanger I've found was on a system that hadn't been properly inspected in years. Annual inspections save lives, not just money.
I'm Omar Jacobo, EPA 608 Universal Certified, co-owner of Frosty's HVAC LLC (TACLA126718E). Here's exactly what happens during a real furnace inspection at your home, step by step.
What Does a Real Furnace Inspection Actually Include?
A real furnace inspection includes 14 distinct safety and performance checks performed over 45-60 minutes on site. If your "tune-up" takes 15 minutes and skips the combustion analysis, it's not a real inspection. Here's the full checklist I run through on every visit.
1. Visual Inspection of the Entire System
Before I touch anything, I look at the whole system. Cabinet condition, flue pipe integrity, gas line connections, electrical connections, condensate drain (on high-efficiency units), and the area around the furnace. Rust, soot, corrosion, or anything unusual gets noted.
2. Filter Check and Replacement
The filter is the cheapest protection for your entire system. I check its condition, note the size and type, and replace it if dirty. Filter replacement is included in the tune-up.
3. Thermostat Review
I verify the thermostat is working correctly, programmed reasonably, and located in a good spot. I'll point out if it's in direct sun, near a supply register, or next to a drafty door where it's getting false readings.
4. Combustion Analysis (Critical)
This is the most important test and the one that separates real tune-ups from surface-level visits. I insert a combustion analyzer probe into the flue and measure:
- Carbon monoxide (CO) in parts per million — should be low, ideally under 100 ppm
- Carbon dioxide (CO2) as a percentage — confirms proper combustion air mix
- Oxygen (O2) as a percentage — confirms burner is getting enough air
- Flue gas temperature — confirms heat exchanger isn't overheating
Combustion analysis is the only way to catch subtle problems in gas combustion before they become dangerous. Any inspection without it is incomplete.
5. Heat Exchanger Inspection
Visual check for cracks, corrosion, rust, and hot spots. On some models I use a borescope camera to see areas not visible to the naked eye. This is the check that catches cracked heat exchangers — which mean full furnace replacement, never repair.
6. Flue Draw Test
I verify that the flue is actually pulling combustion gases out of the home. A blocked or partially blocked flue can push CO back into the living space. This is especially critical in older homes with natural-draft metal flue pipes.
7. Ambient CO Reading
I take CO readings at the supply registers in the main living areas. If the heat exchanger is cracked or the flue is backdrafting, I'll see CO in the breathing air. Normal reading is 0 ppm.
8. Burner Flame Check
A healthy burner flame is steady, blue, and crisp. Yellow, orange, or flickering flames indicate dirty burners, incomplete combustion, or air/fuel ratio problems. I clean burners if needed.
9. Gas Pressure Test
Using a manometer, I measure the gas pressure at the manifold and compare it to the manufacturer specification. Incorrect pressure changes combustion chemistry and causes long-term problems.
10. Ignitor Resistance Check
Hot surface ignitors weaken over time. I measure the resistance in ohms against the manufacturer spec. A weak ignitor causes delayed ignition (which stresses the heat exchanger) and eventually no-light conditions.
11. Safety Switch Tests
I verify that all safety switches trip correctly:
- High-limit switch — shuts burner if exchanger overheats
- Rollout switch — shuts burner if flame rolls back out of the combustion chamber
- Pressure switch — verifies draft inducer is working before allowing burner to light
- Door safety switch — prevents furnace from running with access panel off
Safety switches are last-line defenses. I test each one on every inspection.
12. Blower Motor Amp Draw
I measure the blower motor current draw against the rating plate. A motor drawing more than its rating is showing wear and may fail soon. Early warning lets you budget for replacement before you're scrambling during a cold snap.
13. Capacitor Check
Dual run capacitors on the blower (and sometimes inducer motor) are a common failure point. I measure capacitance against spec and replace if out of range. a full capacitor repair service is billed separately ($500 all-inclusive; $425 for Frosty Club members).
14. Written Report
At the end of the visit, I give you a written report showing every measurement, any issues I found, and my recommendations. If everything is good, that's the report. If I found a problem, you have documentation of exactly what it is and what the repair costs.
Why Does the Combustion Analysis Matter So Much?
The combustion analysis matters because it's the only way to detect subtle safety problems before they become dangerous. A furnace can look fine, sound fine, and even produce heat, while leaking small amounts of carbon monoxide that a combustion analyzer will catch immediately.
What combustion analysis catches:
- Early-stage heat exchanger issues before visible cracks
- Dirty or misaligned burners
- Improper gas/air mix
- Weak draft conditions
- Flue blockages
- Incorrect gas pressure
The Environmental Protection Agency reports over 400 CO deaths annually in the US and tens of thousands of ER visits. Most involve gas appliances. An annual combustion analysis is the most reliable way to catch problems before they harm your family.
Some "tune-ups" from other companies:
- No combustion analyzer (just visual checks)
- Quick filter swap and a sticker
- 15-20 minute visits
- $39-$79 "specials" that don't cover real work
That's not a tune-up. That's a liability shield and a sales lead. Demand the combustion analysis from any contractor claiming to inspect your furnace.
Related: Why Annual HVAC Maintenance Saves You Thousands.
How Much Does a Furnace Inspection Cost in DFW?
A proper furnace inspection at Frosty's is $150 (Member: $127.50). That covers the full 14-point inspection over 45-60 minutes on site, including the filter replacement and written report.
Frosty Club Premium ($300/year) includes:
- 2 tune-ups per year (spring AC + fall furnace)
- $500 off any repair
- 15% off parts
- Priority scheduling
- No overtime charges
Premium members save the full cost of membership on the two included tune-ups alone ($300 in value), plus they get the repair discount and priority scheduling.
Frosty Club Basic ($99/year) is:
- 10% off any repair
- Priority scheduling
- No overtime charges
Basic doesn't include tune-ups, so if you're a tune-up customer, Premium is the better value.
When Should I Schedule My Fall Furnace Inspection?
Schedule your fall furnace inspection in September or October, before the first freeze. My schedule fills up fast once cold weather arrives, and I'd rather find problems in September (when I can order parts and come back without pressure) than during the first hard freeze (when everyone needs help at the same time).
Ideal timing by month:
- September: First priority. Slow season, flexible scheduling, plenty of time to address any findings.
- October: Second priority. Still manageable, but my calendar is filling.
- November: Getting late. Risk of the first freeze hitting before I can get out.
- December-February: Emergency mode. Tune-ups take a back seat to no-heat calls.
If you haven't scheduled yet and you're reading this in October, call me now. I'll fit you in.
Related: How to Prepare Your AC for Spring: The Complete Checklist.
What Happens if We Find a Problem During Inspection?
If I find a problem during your inspection, I'll explain exactly what I found with photos or measurements, quote the flat-rate repair cost, and let you decide. No pressure, no upselling. You can approve the repair on the spot, schedule it for later, or get a second opinion.
Common findings and costs:
Every flat-rate price below covers the complete repair service — diagnosis by a licensed technician, certified parts, labor, testing, and our workmanship guarantee. These are not part-only prices; they are the total, all-inclusive cost to fully resolve the problem at your home.
Our complete dirty flame sensor repair service — diagnosis, licensed technician, certified parts, labor, and our workmanship guarantee — runs $350-$500 ($297.50-$425 for Frosty Club members). A full weak ignitor repair, covering the service call, diagnosis, parts, labor, and testing, is $350-$500 ($297.50-$425 for Frosty Club members). For a total failing capacitor repair — including all parts, labor, system testing, and our guarantee — the flat rate is $500 ($425 for Frosty Club members). The full-service failing limit switch repair (EPA-certified technician, parts, labor, testing, and warranty) is $350-$500 ($297.50-$425 for Frosty Club members). Our complete worn blower motor repair service — diagnosis, licensed technician, certified parts, labor, and our workmanship guarantee — runs $750-$1,500 ($637.50-$1,275 for Frosty Club members). A full cracked heat exchanger repair, covering the service call, diagnosis, parts, labor, and testing, is FULL SYSTEM REPLACEMENT ($8,000-$20,000+ for Frosty Club members). For a total failing gas valve repair — including all parts, labor, system testing, and our guarantee — the flat rate is $500-$800 ($425-$680 for Frosty Club members).
If I don't find anything, I'll tell you that too. Not every inspection turns up a repair — most don't, honestly. That's the point of preventive maintenance. You catch problems before they're expensive.
Schedule Your Fall Furnace Inspection
Don't wait until the first freeze to think about your furnace. Call me now, book a September or October tune-up, and go into heating season knowing your system is safe and ready.
Call (469) 254-0548 or request service online.
Serving Farmers Branch, Coppell, Irving, Flower Mound, Lewisville, and Grapevine.
Thinking about replacement? Check exact pricing. Join Frosty Club Premium to get two tune-ups included per year — learn more. Meet the family behind Frosty's.
143 Google reviews, 4.9 stars, TACLA126718E, since 2018.
Related Articles
- Why Annual HVAC Maintenance Saves You Thousands
- How to Prepare Your AC for Spring: The Complete Checklist
- AC Tune-Up Checklist: What Your Tech Should Inspect
Written by Omar Jacobo, EPA 608 Universal Certified Lead Technician at Frosty's HVAC LLC. Family-owned since 2018, 143 Google reviews at 4.9 stars, Texas License TACLA126718E. Serving DFW homeowners with flat-rate pricing and no surprises.
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