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Commercial Case Study · Guthrie, Logan County

They cut the ribbon at three o’clock.
I had a man on the roof at three o’clock.

4.8 stars, 300+ Google reviews

Master HVAC License
Licensed Oklahoma Mechanical Contractor
NATE Certified
HVAC/R since 1980
Dave Hartzell in a wide-brim hat reading the wiring schematic mounted inside the open access panel of a commercial rooftop unit at sunset
Tracing the control circuit on the unit’s own wiring diagram, on site in Guthrie. This photo carries no camera timestamp, so it is not dated here.

Guthrie’s new McDonald’s set a world record getting to opening day: an empty
lot to a fully operational restaurant in 55 days, according to the
Guthrie News Leader
and the company officials it quoted.

The grand opening was a Friday in September, ribbon cutting at three in the
afternoon, cars backed up out of the lot and people lined up to get in the door.

The building had no air conditioning.

They called me at one o’clock. I had a man on that roof at three, while the ribbon was
being cut out front. It was 105 degrees on that roof and the kitchen was as hot as you can
imagine with a full house and a full grill.

What I walked into

Brand new equipment. Somebody else had installed it, somebody else had already been in
it before me, and it would not run. I found burnt parts on a building that had been open
for a matter of hours.

We replaced a control transformer Friday afternoon and the unit still would not stay up.
It kept throwing a phase monitoring fault. I checked the voltage balance and the voltage
was fine, which told me whatever had burnt that transformer was feeding a bad signal to the
phase monitor. I went to the manual and found the transformer lands on the same connection
as the phase monitor. That was the thread to pull.

By the end of Friday I had four of the six condenser fans and two compressors running.
Two of those fans are variable speed, pulse width modulated, and the control board was gone,
so there was no way to drive them. That is as far as anybody was getting that night.

Technician in a white hard hat working inside an open commercial rooftop package unit under a blue sky
On the roof in Guthrie, Friday, September 4, 2026 at 3:52 pm. Time is the camera’s own timestamp.

Saturday

I went back Saturday with the crew. We pulled the two variable speed motors, put in
standard motors, and tied them into the contactors on the compressors so they would run with
the machine instead of waiting on a dead board. We bypassed the drive on the indoor blower.
By Saturday evening the whole system was cooling and the restaurant stayed open all weekend.

That was temporary and I said so at the time. The factory parts were a week out. My job
that weekend was to keep a brand new restaurant open in 105 degree heat on its opening
weekend, and that is what we did.

Why I am telling you this

Most commercial contractors around here will not take a call at one o’clock on a Friday
and be on a roof by three. Most will not come back Saturday. I did both, on a system I did
not install, with someone else’s problem in front of me, in September heat.

If you run a restaurant, a store, a clinic or a shop, that is the thing worth knowing about
whoever you call. Not the brochure. Whether they show up on the worst possible day.

For commercial pricing, response times and what I service across central Oklahoma, see my commercial HVAC page. If you run a restaurant, my restaurant HVAC page covers makeup air, grease and walk-in questions, and my rooftop unit repair page explains how rooftop package units fail and how I diagnose them.

A clamp meter hanging in the opened control section of a commercial rooftop unit, with circuit boards, compressor and copper refrigerant lines visible
Electrical testing at the open unit, Friday, September 4, 2026 at 3:52 pm. Camera timestamp.

What a commercial call costs

My commercial diagnostic is $389 flat on light commercial equipment up to
15 tons, and it is the same number day or night. No after hours uplift, no surprise. You can
book it online. Anything bigger than 15 tons gets sized by my tech on site, because you should
not have to know your rooftop’s tonnage to book a service call.

1

I answer and I show up

Called at one, on the roof at three, on a Friday, in another county.

2

I diagnose before I sell you parts

The transformer was a symptom. The phase monitor and the burnt board were the story.

3

I tell you what is temporary

Bypasses buy you time. I say that out loud instead of calling it a repair.

Questions I get about commercial work

How much does a commercial AC diagnostic cost in Guthrie Oklahoma?

$389 flat on light commercial up to 15 tons, day or night, no after
hours uplift. Bigger equipment gets sized by my tech on site.

Do you work on commercial rooftop units in Logan County?

Yes. Logan County is one of the seven counties I run every day, along
with Kingfisher, Canadian, Oklahoma, Garfield, Major and Blaine.

Will you work on equipment somebody else installed?

Yes, and I do it often. I will tell you what I find without dressing
it up, including when the problem was there before I got to it.

Do you do weekend and after hours commercial calls?

Yes. Commercial is $389 flat day or night. A restaurant that is down
on a Saturday cannot wait until Monday and I do not pretend otherwise.

What if the parts are not available right away?

I will tell you straight, get you running temporarily if it can be done
safely, and put in writing what still has to be done when the parts land.

How fast can you get to a commercial call?

Most calls inside my seven counties are same day. On this one I was
called at one o’clock and had a man on the roof at three, in a neighbouring county.

This is one of my real jobs. My completed jobs in Guthrie are listed on my work page, with 6,500+ across Central Oklahoma. 4.8 stars, 300+ Google reviews.

Got a building that is down?

I will tell you what is wrong and what it costs before I fix it.

Call 405-375-4822

Or book online at hartzellsheatair.com

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