SOUTHEAST WISCONSIN’S HVAC EXPERTS

ESTABLISHED IN 1962

OUR STORY

Continuing a Tradition of Exceptional Heating and Cooling Services

What began in a garage in 1962—with Gordy and John Cole’s commitment to offering honest, high quality HVAC service—continues today at Interstate Heating Co. in Sussex. We’ve grown to offer the latest heating, cooling, and air quality products, and our service area now covers all of southeastern Wisconsin.

We are three generations strong and still follow the most basic rule of business: we treat our customers the way we want to be treated.

About Us

WHAT OUR CUSTOMERS ARE SAYING

Google Rating

4.9

Based on 592 reviews

Interstate Heating Co., Inc.

4.9

Karl Fritchen

23:08 25 Jun 25

We came back from out of town last night and our house was over 80 degrees. Jake came out this afternoon and changed the capacitor and recharged the system and we are back enjoying the cool home tonight! Jake was very courteous and explained everything to us very clearly. He was a pleasure to work with and the staff at the office was awesome squeezing us in today! Thanks!!!

Cathleen Esselstyn

20:39 25 Jun 25

My air conditioner broke during this extremely hot spell. Interstate came out in a timely manner. Dylan was on time, polite, knowledgable & explained services and options, and fixed the problem. I've been with Interstate Heating and Cooling for 28 years.

Marnie Omer

19:21 25 Jun 25

Chris was excellent. He was efficient and very tidy. Thank you Chris for getting our AC running effectively again!

Larry Brand

18:17 25 Jun 25

Jake is awesome to work with. He is very positive, persistent and methodical.

Scott Larson

19:54 24 Jun 25

6/24/25 ..The technician's/Pauly Scott, were excellent on the installation of the air-conditioner and explaining everything to me and assisting me with the control unit/Nest system. I'd recommend using Interstate since every time I've had technician's come to my home they have been excellent.Scott Larson

John Schwitz

16:02 24 Jun 25

Technician was very friendly and knowledgeable. Was very thorough and explained everything he was doing and showed me the results from all the tests he had done. I would recommend Interstate Heating to anyone needing service.

Mary W

14:03 24 Jun 25

Interstate Heating and Eric get 5 stars from us. My elderly mother's central air went out just before a heat wave. Eric was able to get a quote written same day, I signed it on a Saturday and by Monday morning the crew was installing the unit. 8 hours later the house was back to 72 degrees. The heat wave rages on and we already have the new unit. Great service and great crew. We are very pleased with the work done and recommend anyone work with Eric and Interstate Heating.

E.W.

12:39 24 Jun 25

Josh is the man! Our house is cool again. Couldn’t be happier with our service. Thank you!

Trisha Stahl

18:31 23 Jun 25

Jake was professional, kind and intelligent. Air conditioning went out during the hottest day and they fit us in same day. Had everything running again in less than a hour.

18:01 23 Jun 25

14:40 23 Jun 25

13:33 23 Jun 25

22:07 20 Jun 25

Tristan was my service technician and he did a wonderful job. I have the 2 year/4 inspection service package. Tristan was very professional and personable and explained everything that needed to be done to keep my somewhat old air conditioner running for the season. I highly recommend Interstate Heating Co., Inc.

Beatriz Cirera

14:10 20 Jun 25

RDR .Lepkowski

18:09 19 Jun 25

The service tech was very informative and thorough when servicing the air conditioner. Would recommend interstate for an install or service.

Douglas Jacobson

20:42 18 Jun 25

Scott Schumann

14:39 18 Jun 25

Cindi Vetter

15:09 17 Jun 25

Such friendly, competent, and hard working gentlemen! I’m so glad someone referred me to them. Will continue to use them for sure!

Gary Puestow

21:30 13 Jun 25

Patti Sprague

21:00 13 Jun 25

Eric was professional and he was quick and honest. Seeing that my furnace is 38 years old I'm sure it's time for a new one and that's exactly what he told me.

Rachel Detert

20:57 13 Jun 25

Great service, very professional. Maintenance program has excellent value and has found issues before they become larger problems and promptly fixed.

ecsdigital2112

15:51 13 Jun 25

Service guys were very helpful. The answered all my questions and explained every process that pertained to my situation.

jan mueller

17:55 12 Jun 25

Erich did a great job. Explained everything very conscientious, clean and efficient. Very knowledgeable about the product. Great job.

Robert Pierce

14:50 11 Jun 25

The kind of person I would like on my team Jash

Candice Feider

22:17 10 Jun 25

David Carpenter

17:11 09 Jun 25

Josh does a great job. Listens to concerns and addresses them in a systematic manner. He has serviced our HVAC more than once and would welcome him back.

Dean Oswald

22:48 06 Jun 25

Had equipment needed and did a thorough inspection and was very courteous.

Mike (Mike 'Nerds' Neldner)

21:02 05 Jun 25

First time customer, very impressed with the level of service, knowledge, and professionalism of Interstate's technicians. From the first phone call to get scheduled, and through the service call at our home, they were helpful, informative, and helped me get the feel for what we had for options on resolving our hvac needs.I'll be a returning customer, that's for certain. Keep up the great work!

Deborah Kravit

18:58 05 Jun 25

Very professional and knowledgeable technicians

Fred Kinateder

13:51 05 Jun 25

Josh did a great job. I was very satisfied with the service. He also gave me some suggestions as to my options for repair or replacement.

Michael Honisch

21:16 04 Jun 25

Great job by all technicians we've met over the past year, after leaving our previous recently sold VERY long-term HVAC contractor

Holly Nelson

14:15 04 Jun 25

Interstate does a great job servicing all our needs. Highly recommend.

Raymond Riemersma

18:44 30 May 25

GreatHe did a good job

Mindy Lloyd-Noel

18:15 30 May 25

Eric is the best!!! I will specifically ask for him for all my services. He’s so nice, and knowledgeable! This business is lucky to have him.

Tom Adler

14:15 30 May 25

Both Tristan and Alberto were great! On time, conscientious and focused on service. Clearly explained what they were doing to do and what was found. Efficient.

john seipel

15:00 28 May 25

Tristen and Alberto were amazing Techs…informative and caring and happy…which is very rare these days so I believe it’s precious!!

Kevin Webb

20:39 27 May 25

Honest advice!

Michael Urban

16:43 23 May 25

Great professionalism and communication from Tristan and Alberto.

Harold Krueger

15:31 23 May 25

Chris was conscientious in performing his work and kindly instructed me in the programming of our new thermostat. I have engaged Interstate for years and will continue to do so.

Michael Clark

14:47 22 May 25

Technician was friendly and professional. Answered all my questions!

Cheryl Milbauer

18:26 21 May 25

I have been thoroughly impressed with each person I have worked with at Interstate - office, sales, techs - everyone is focused on fixing your problem and offering solutions. I recently pivoted away from a mini-split unit to an upgraded sensor to solve an issue I have been having. Would recommend Interstate to anyone looking to partner with a HVAC provider.

Michael Zimmer

16:55 19 May 25

Eric was highly knowledgeable, friendly and thoroughly answered all of our questions. Will use Interstate again

Mary Clayton

13:54 19 May 25

We decided to replace our AC unit as it was 28 yrs old. Never had a problem, but time was not on our side. We called Interstate and everything went very smoothly. Installed in just a few hours. They did a great job. Highly recommend. They have been our go to guys for over 20 yrs. Very respectful of our needs and property!

MaryBeth Haugen

01:38 17 May 25

David Misorski

17:59 15 May 25

Very professional and courteous service.

Gina Woida

23:46 14 May 25

Prompt, communicated arrival time, explained what they found and what they repaired. Very efficient, very friendly.

Joanne Feypel

00:39 14 May 25

I had this company come in to check and clean my air conditioner. Did a beautiful job . It was dirty due to construction in our subdivision. He let me know what to watch for in my furnace for future problems. When that happens I will call them back.

Ross Read

19:29 13 May 25

Mark Treadaway

13:22 12 May 25

Efficient, polite, and professional

Richard Bauch

17:12 09 May 25

Christopher Mertens

23:29 02 May 25

Great service, troubleshot through some unexpected problems and kept me informed the whole time with what options we had. Appreciate Josh's work with us!

Amy Krenke

16:20 02 May 25

Great service, great techs. Very happy working with Interstate.

Carol Hemmingsen-Scheller

13:01 01 May 25

Red Rose Dentistry

18:07 30 Apr 25

He was very efficient, helpful, knowledgeable and timely. Thank you!

Keith Redding

13:03 30 Apr 25

don mantz

19:44 29 Apr 25

Eric Osterman is always a pleasure to work with. He knows the heating business and communicates well. He completes the project in a professional manner and reviews what he did with us. Top member of your team.

Thomas Weghorst

17:44 25 Apr 25

Great tech...explained everything very well and was very thorough.

Art Jaehnke

19:35 18 Apr 25

William Wright

18:14 18 Apr 25

Very receptive to our needs. Excellent work and very honest. They have the best service and personnel in the entire area.

Juliet Mock

09:45 18 Apr 25

Chris C was awesome! So very kind, and efficient. He explained things well and was very professional. Really appreciated the quick response to the online inquiry, ease of scheduling and professionalism of all the team members we had interactions with. We will definitely use their services again when needed.

John Warczak

01:55 15 Apr 25

Eric, Interstate's service tech, did an excellent job. He was personable, professional, efficient and clearly explained what was done.

Sanjay Singh

23:09 11 Apr 25

The team at Interstate at Sussex has been outstanding for all the 3 years that I have availed their services. From the initial phone experience for scheduling, contract information and upfront capabilities - to when they come over for emergency or scheduled maintenance. Thy will even call you to remind that your prepaid service is due!The technical staff is excellent. Josh has been exceptional in intelligent diagnostics, addressing your queries and going over your system meticulously to give reasonable solutions without pushing spares or replacements, when you know you don't need them!I would recommend them wholeheartedly for all planned service contracts as well as emergency needs.Kudos and keep it up!

Drew Hietpas

12:53 11 Apr 25

Wayne Bernhardt

19:08 10 Apr 25

Both guys were polite and did a good job. Thank you.Wayne Bernhardt

Joel Anders

13:17 10 Apr 25

Interstate did a great job after a lightning strike hit our house diagnosing the problem. Technician Eric returned timely with the needed parts and completed the job.

Ronald Troy

20:17 09 Apr 25

Ethan and Kevin already do a great job - very reliable, responsible, and knows the equipment.

Florence de Leon

03:26 08 Apr 25

Gregg Bergin

21:35 31 Mar 25

Josh my installer was great. He installed my new Carrier Thermostat in quick order, and explained everything in easy to understand directions. My new thermostat plays nice now with my Aprilaire whole house humidifier. The Carrier app seems to be pretty easy to understand as well.

Lori Talb

19:08 31 Mar 25

LINDA KARL

20:28 28 Mar 25

I was very impressed with Lukes job well done. He deserves above (and beyond 5 stars. 10 stars instead of 5) for an exceptional job well done. Luke went out of his way to make sure all issues were taken care of in a timely manner. Thanks Luke!

John Wahlen

19:27 28 Mar 25

Chris rocks

Gary Bennetts

00:38 28 Mar 25

On time as scheduled, honest, and did a great job

Matt Janke

20:15 27 Mar 25

Being out of town while having heating issues, Josh was awesome at identifying the issues, fixing them and just making everything run more efficiently. He was also really great at communicating with us. Great service from everyone at Interstate!

Kevin Powalisz

13:29 27 Mar 25

Outstanding service!Chris and Josh both followed up to make sure everything was working properly.Would highly recommend. This is a company that cares!

Danny Cull

12:18 27 Mar 25

Interstate was a pleasure to work with. My furnace went out and the next day they came in and installed. Very professional friendly install team, very fair pricing on the unit. Would highly recommend them and will continue to use them for service at my home.

Carol Brook

21:31 24 Mar 25

Knowledgeable , friendly and did a great job job. Would definitely recommend your company to others.

Kevin Klingbeil

20:27 18 Mar 25

Quick response time. Eric was Honest, Understanding and took the time to Thoroughly answer all of my questions on go forward options!Highly recommend!!

Brad Kollath

18:41 18 Mar 25

Randy Breske

10:40 14 Mar 25

Great quality, very professional and knowledgeable service technicians, great respect for our property

Michael

19:26 12 Mar 25

They installed my hydronic heating system and hot water system in 2007. I've used them for 18 years to do all the repairs and maintenance. They are always professional and til notch.

Tyler Faber

18:43 10 Mar 25

I recently had the pleasure of working with Interstate Heating, and I can’t say enough great things about their service! From the moment I called, their team was professional, friendly, and incredibly knowledgeable. They took the time to understand my heating issues and scheduled an appointment quickly.The technician arrived on time, was courteous, and explained everything in detail before starting the work. It was clear they were experienced and genuinely cared about doing the job right. My heating system was up and running efficiently in no time, and they even provided helpful maintenance tips to keep it in top shape.Interstate Heating exceeded my expectations in every way—fair pricing, top-notch customer service, and expert workmanship. I highly recommend them to anyone in need of heating services. They’ve definitely earned a lifelong customer!

Linda Hrdina

17:09 10 Mar 25

Eric notified me in advance of his arrival. He was very helpful in identifying a noise in the ductwork and a solution to fix it. Eric was polite and professional. I would definitely recommend Eric and Interstate Heating.

Mike Nast

16:45 06 Mar 25

On time and very friendly. Technician Josh did a great job, very professional and knowledgable

Rick Noe

15:39 05 Mar 25

Eric is incredibly knowledgeable, doesn’t mess around and gets things done better than any HVAC person I have ever dealt with! He’s a real gem for Interstate and will keep me coming back for products and service. THSNKS ERIC & INTERSTATE!

Dean Maytag

17:53 03 Mar 25

Excellent, the technician (Josh) was very knowledgeable and personable. Did a thorough examination of our furnace. In addition, he came with a mask at our request and wore booties to protect or carpet. Much appreciated!

Dennis Herricks

20:26 26 Feb 25

Bill Kuckuk

19:54 25 Feb 25

Our furnace stopped working. I called Interstate and they were able to schedule service for the same day. Josh showed up in a couple of hours, quickly diagnosed the problem and had the parts in his van. Fast, efficient and friendly. That's the good news. The bad news is this is the second time in 6 years that our new Carrier system has failed. Luckily the parts were covered by warranty, but the trip charge and installation labor are not. Bottom line...happy with Interstate, not happy with Carrier.

Bill & Diane Kuckuk

00:43 25 Feb 25

While I’m not happy at all that my Carrier A/C failed after only 5 years, leaking out $500 of refrigerant and requiring another $500 in labor to repair, I couldn’t be happier with Ethan as our technician. He explained everything he was going to do, how much it was going to cost and was very polite and respectful. I would definitely call Interstate for future HVAC needs, but I can’t say I would choose Carrier again.

Mark Shandley

23:54 24 Feb 25

Great service. Quick to resolve problem. Great crew. Good product.

Fred & Jane Lawler

21:34 21 Feb 25

Guys we’re very professional

thebigcucumber

16:21 21 Feb 25

very polite and knowledgeable, easy to talk to.

zak badani

18:28 20 Feb 25

Down to earth people to work with. They will check if parts are covered under Warranty or recalled.

Katie Bosbous

17:45 20 Feb 25

Eric Osterman was fantastic. Very personable and kind. Knowledgeable as well! Thank you!

Chet Nielsen

16:39 19 Feb 25

Interstate's heating tech was very responsive. A quality we truly appreciate.

Gerry Buck

15:10 19 Feb 25

Prompt, knowledgeable service and a reasonable charge. I would definitely recommend Interstate Heating.

sarah Schmidt

13:22 18 Feb 25

Friendly Fast service!

Randy DeLaura

23:00 14 Feb 25

James Schroeder

19:28 14 Feb 25

Excellent experience. Eric was very professional and knew his stuff.

Fidel Mangwiza

22:02 13 Feb 25

Eric was great to work with. He is very knowledgeable and he explained what he was doing, and why he was doing it. I was very impressed by his professionalism and great customer service. Thank You Eric!!

rick fricker

17:33 13 Feb 25

Very good repair man excellent service

See all reviews Write a review

“Josh is the best. No one works harder. Our house is old and there have been multiple add-on HVAC units along the way. It is complicated and we've had numerous issues along the way. He is great about informing us what is going on and working to resolve any problem.”

- Bryan H.

“Jake was out early and got our unit repaired on one of the hottest days of the year. He recommended a replacement unit as ours is over 30 years old. He'll be back to replace.”

- Mike B.

“Eric does the semi-annual maintenance on our furnace. He is always on time and gets the job done professionally and thoroughly. He’s always happy to explain what he’s done on each visit and give us tips on what we need to do to help our furnace run at maximum efficiency.
Eric brings years of experience to the job and it shows in the high quality of his work.”

- Sheila B.