I have been using Mark for a few years now, maintaining our HVAC systems both at our old house and now at our new house. He is very responsive, honest, and a great trouble-shooter. He thinks like an engineer which I appreciate. Mark recently installed a new Heil HVAC system (2-stage gas furnace and 2-stage A/C) in our new home. The installation went very well and the new system works great! I would highly recommend Mark Olis for any HVAC needs.
RunBikeSwim
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June 16, 2026
Mark's reputation precedes him, and his work stood up to all the positive reviews he's received. Mark installed a two-stage variable speed system (A/C and furnace) for a much more reasonable price than the larger companies offered. He also repaired an auxillary heat pump vs trying to sell me a new one. The difference with Mark is he tells you what you need without the upselling headache. Larger providers tried to sell humidifiers, ionization add-ins, extended warranties, etc, whereas Mark asked questions to determine if I really needed them (I didn't). Mark shows up and does what he says he will do. It's a no-brainer to use Mark in the future as well as refer others, which I will do at every opportunity. He is hard-working, honest, and pleasant to speak with. Why can't all businesses run this way?
Mark Nelson
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June 03, 2026
Mark does a great job identifying the issue and explaining the problem before the repair. He definitely has the mindset of fixing it first. I definitely recommend him and have been using him for years.
Richard Niewiadomski
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April 06, 2026
Mark showed up within few hours of calling. Replaced a blower motor on furnace and total cost came in well below the quoted price I received from a larger HVAC company. If you want fast, quality service and great prices-Call Mark
Scott Gretz
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November 26, 2024
Excellent experience. Mark is on time and very knowledgeable. From inquiry, to quote to install the process was smooth. Great to support local independent contractors that live and work in our local community.
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484 E Carmel Dr, Carmel, IN 46032, USA
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I have been using Mark for a few years now, maintaining our HVAC systems both at our old house and now at our new house. He is very responsive, honest, and a great trouble-shooter. He thinks like an engineer which I appreciate. Mark recently installed a new Heil HVAC system (2-stage gas furnace and 2-stage A/C) in our new home. The installation went very well and the new system works great! I would highly recommend Mark Olis for any HVAC needs.
Mark's reputation precedes him, and his work stood up to all the positive reviews he's received. Mark installed a two-stage variable speed system (A/C and furnace) for a much more reasonable price than the larger companies offered. He also repaired an auxillary heat pump vs trying to sell me a new one. The difference with Mark is he tells you what you need without the upselling headache. Larger providers tried to sell humidifiers, ionization add-ins, extended warranties, etc, whereas Mark asked questions to determine if I really needed them (I didn't). Mark shows up and does what he says he will do. It's a no-brainer to use Mark in the future as well as refer others, which I will do at every opportunity. He is hard-working, honest, and pleasant to speak with. Why can't all businesses run this way?
Mark does a great job identifying the issue and explaining the problem before the repair. He definitely has the mindset of fixing it first. I definitely recommend him and have been using him for years.
Mark showed up within few hours of calling. Replaced a blower motor on furnace and total cost came in well below the quoted price I received from a larger HVAC company. If you want fast, quality service and great prices-Call Mark
Excellent experience. Mark is on time and very knowledgeable. From inquiry, to quote to install the process was smooth. Great to support local independent contractors that live and work in our local community.