The Human Diagnostic
Looking for honest stories about people, not product reviews? You're in the right place.
The Human Diagnostic isn't a how-to HVAC podcast. It's what a 45-year Master Technician notices about people after 90,000 service calls across gas plants, oil rigs, hospital preservation systems, high-rises, feedlots, walk-in freezers, and residential homes all over Central Oklahoma.
Hosted by Dave Hartzell, each episode tells a real story from a real service call. Sometimes he's driving to the job and predicting what he's about to walk into. Sometimes he just left and he's still working through what he saw. Either way, the story turns out to be about more than HVAC.
Topics you'll hear across the season:
✅ The customer nobody wanted to take, and what changed when someone finally did
✅ Why the person researching their broken AC at midnight isn't being difficult, they're scared
✅ What 45 years of walk-ins, weddings, funerals, and broken water heaters teaches you about anxiety
✅ The tech who can fix anything but can't explain it, and why the customer doesn't trust him
✅ The review you can't place, the moment you never forget, the call that changed how you work
✅ What gets lost when we treat people like tickets, and what gets found when we don't
Whether you fix things for a living, manage people who do, or just like good stories from someone who has been everywhere and met everybody, The Human Diagnostic gives you the part of the job that never shows up in an invoice.
📍 Proudly based in Kingfisher and serving Edmond, Guthrie, Yukon, Mustang, Piedmont, Logan County, Canadian County, Blaine County, Major County, Garfield County, and the greater Oklahoma City metro area. Hartzell's Heat & Air blends old-school integrity with cutting-edge technology, from digital diagnostics to smart-home HVAC integrations.
Connect with Hartzell's Heat & Air:
📲 Facebook: facebook.com/hartzellsheatair
🐦 X (Twitter): x.com/HartzellsHVAC
▶️ YouTube: youtube.com/@hartzellsheatair6003
💼 LinkedIn: linkedin.com/in/dave-hartzell-7a687515
📧 Contact Us: office@hartzellsheatair.com
Every call is a story. Every story is a person.
🔔 Subscribe to The Human Diagnostic and ride along.
📞 Need HVAC help in Central Oklahoma? Call (405) 375-4822
🌐 hartzellsheatair.com
Episodes
198 episodes
The Repair Estimate She Couldn't Accept Without a Second Opinion
He asked me what it was going to cost before I had the lid off the unit, and when I said I didn't know yet, he asked again, slower, like I hadn't heard him. Late July, the kind of week where the sun is already working at seven in the mor...
He Was Certain He Was The Reasonable One About The Heat Pump
He told me the last company had been working him, and about nine seconds later he told me exactly what was wrong with his air conditioner and how he knew. Late August, one of those weeks where it never gets below eighty at night and the ...
The Woman Who Couldn't Believe the Repair Held
By the time I pulled out of the shop she had called three times, and nothing about her job had changed since the first one. First full week of July, heat index sitting around 105 by early afternoon. Two story house in one of the newer ad...
The Repair He Feared Less Because He Could See It Coming
He picked the more expensive repair and looked relieved doing it. Late August, a brick ranch on the edge of town, the kind built in the nineties with the condenser tucked up against the north wall where nobody ever hears it run. Retired ...
The Worry She Was Certain Showed While the Heat Pump Ran
She had been terrified about the money for two hours and I had no idea, because she thought it was written on her face. Early spring, a rent house out toward the county line, tenant not owner, which changes the whole shape of a call. You...
The Repair She Put Off Because Bad Luck Happens To Others
He agreed with every word I said about the failure, and then explained why it would not happen to him. Composite call. This is four or five conversations stacked into one, because the pattern is the point and I am not putting a real cust...
The Man Who Had to Believe He Broke the Heat Pump
He had set the thermostat to sixty on a hundred and four degree day, and he genuinely believed that would make it cool faster. Mid July, a two story on the east side of Kingfisher, the kind with the big west windows nobody thinks about w...
Duct Repair: She Wanted The Same One Back
She asked me if I could put the same one back in. The exact same one. And she was not being difficult, she was being loyal. Late June, a brick ranch south of the tracks, the kind with the deep front porch and a swing that has been painte...
The Ninety Dollars She Saved That Cost Her A Furnace
She had saved ninety dollars a year for six years, and it cost her forty two hundred. I want to be careful with this one, because there is a version of it that is a sales pitch and I am not interested in telling that story. The story I a...
The AC Repair He Diagnosed Himself And Got Wrong
The man knew exactly what was wrong with his air conditioner until I asked him to show me. It was a Thursday in the first week of August, out past the co-op on the north edge of town. Ninety-nine degrees and the kind of still air where t...
Fixing the AC and cooling tempers
The house was eighty-four degrees when I walked in. That number matters. Not because eighty-four is the hottest house I have ever walked into. It is not. I have walked into houses that felt like attics. I have walked into homes where the...
The AC He Fixed Himself and Loved Beyond Its Worth
I am driving out to a call right now where I already know the hardest part of the job will not be the equipment. It will be the man. Not because he is difficult. Because he built the thing himself, and a man cannot see clearly the thing his own...
The Repair Each of Them Swore Another Had Called In
I once worked on a rental house where the furnace had been dead for three weeks in November, and not one single person had decided it was their job to call somebody. There were four people who could have. Every one of them figured one of the ot...
He Was Sure the Old Owner Deserved the Broken Heat Pump
I left a house this afternoon where the furnace was not the real problem. The furnace was just old and tired and finally quit, the way furnaces do. The real problem was that the woman who owned it was certain she had done something to deserve i...
Why the Familiar Heat Pump Man Felt Like a Friend
A woman hired me once for a reason that had nothing to do with whether I was any good. She told me so herself, right there on the porch, before I had even opened my bag. I have seen your truck go by for years, she said. That is why I cal...
I Blamed His Temper, Then I Saw the Dead Heat Pump
A man decided I was a crook before I finished writing up the diagnosis. I could see it land on his face. I had told him his system needed a new condenser fan motor and a hard start kit, gave him the number, and his jaw set and his eyes w...
The Face I Held Together While the Repair Fell Apart
A customer once told me I was the calmest man she had ever met. I thanked her. I did not tell her the truth, which was that I had been up since four with a sick dog and a bad night, and the calm she was admiring was something I had put on that ...
Her Fear Reached Out Instead of Running, Heat Pump Down
Her air conditioner had been dead for two days in August, and the first thing she did when I walked in was offer me lunch. Not water. Not a chair. Lunch. She had a sandwich made before I had my tools out of the truck. The house was hot e...
Why She Repaid a Stranger's Good Turn at the Heat Pump
A woman in Kingfisher tried to pay me for a fuse I had replaced on a fan motor. It was a two-dollar fuse. I had been at the house for fifteen minutes total. I had told her there was no charge. She did not believe me. She tried to give me...
The Heat Pump He Talked Himself Into Loving
A man in Kingfisher, six weeks after he had bought a system he had been on the fence about, told me he was so glad he had gone with that one. He said the other quote had been a mistake. He said the brand he had not chosen was actually known for...
Why His Gut Ruled Out the Repair That Worked
A woman in Watonga told me, in her kitchen, that she did not want the variable-speed unit because it sounded like it was going to be complicated. She did not mean it would make a complicated noise. She meant the word complicated. She had...
The Heat Pump He Defaulted To Without Thinking
A customer in Okeene, after I had spread three replacement quotes on her kitchen table and walked her through them for forty minutes, looked at me and said, whatever you think is right. She had heard the differences. She had nodded at th...
Why She Couldn't Unhear the Heat Pump After That Day
A customer in Hennessey told me, two weeks after I had installed a new heat pump in her house, that she could not believe how many heat pumps were going in around town now. She said she saw them everywhere. She named six driveways within a mile...
The Warning He Only Believed After the Repair
A woman in Dover told me, after I had condemned her compressor, that she had known all along it was going to go out this summer. She said she had felt it. She said the unit had been telling her since spring. I asked her, gently, what the...
He Praises Old Iron and Forgets Each Failed Repair
A man in Calumet pointed at his furnace in the basement and told me they do not make them like they used to. The furnace was forty-one years old. It still ran. It had three relatives in the neighborhood that had failed twenty years ago and been...