
For over 90 years, the team at Thielmann has provided customers in Waukesha, Wisconsin with reliable, top-notch HVAC repair services. From heating and cooling to air quality and installation, we do it all so you can rest assured your home will be in its best condition and your family will be comfortable.
We also know life gets busy—that’s why we offer easy, convenient scheduling. Give our technicians a call at (262) 315-3067 or fill out our online form and someone will get back to you quickly.
Our Professionals Will Keep Your House Comfortable During the Fall, Winter, Spring, and Summer Seasons
The average temperatures in Waukesha, Wisconsin are radically different from winter to summer. Winters are known for being freezing, with some of the coldest months having temperatures in the low 20s. In contrast, the summers are humid, warm, and muggy.
Summer temperatures in Waukesha hit around 75°F but can get up to 90°F. The humidity from the surrounding lakes and rivers makes it feel hotter in the local area. Stay cool in this summer heat, and cozy and warm in the winter, when you work with our team of NATE-certified technicians. We will keep your house habitable throughout each season by helping you maintain your furnace, heat pump, boiler, or central air conditioner.
Air Conditioner Replacement and Installation Services
Sometimes, your air conditioner is on its last leg and the best move is not to repair it but to replace it completely. If this is the case our team of certified technicians is ready to help. With decades of experience in AC installation and replacement, we can handle putting in a new AC unit for you from start to finish.
We also provide heating and cooling services in Waukesha, Wisconsin for the best brands on the market and have flexible, easy financing options so you can stay within your budget.

Air Conditioning Repair Services
Summers in Wisconsin can get muggy and hot. Make sure your home is up for the task of keeping you cool by scheduling air conditioning repair or air conditioning tune-up services.
The best way to ensure your system is ready for summer is by having a technician come over and assess the condition of your air conditioner to confirm if it requires repairs.
Here are some of the components of an AC system we will check to see if it needs repair:
- Evaporator coil
- Compressor
- Condenser coil
- Expansion valve
- Filter
- Fan
We also offer air conditioner installation services for old systems that cannot be fixed. If you notice any weird noises, strange smells, or a lack of cold air, chances are you will need a repair or replacement.
Ductless Mini-Split Services
Homeowners in Wisconsin love ductless mini-splits because they are great for the ever-changing weather, from the frigid winters to the humid, muggy summers. Ductless mini-splits are super versatile and offer both heating and cooling options.
We offer the following mini-split services:
- Installation
- Replacement
- Repair
- Maintenance
- Inspections
Our team offers superior HVAC repair services and is fully equipped to handle any ductless mini-split issues, like refrigerant leaks, compressor problems, drainage malfunctions, frozen coils, electrical problems, blower issues, weird noises, and more.
Furnace Repair and Tune-Up Services
Keep your home warm and cozy for the winter with our reliable furnace repair and tune-up services for local residents in Waukesha, Wisconsin.
We can work on any system you have, like:
- Gas furnaces
- Oil furnaces
- Heat pumps
- Packaged units
- Boilers

Furnace Installation and Replacement Services
We can install gas, oil, or electric systems for your convenience. Whether your old system is on the fritz and you need a furnace replacement, or you have a brand-new property and need a furnace installed, we will take care of it.
Heat Pump System Installation Services
Wisconsin residents also use heat pumps to stay warm in the cold winters. Our NATE-certified technicians specialize providing extensive heating and cooling services in Waukesha and will keep you updated from start to finish on the project.
To receive support with a heat pump installation or heat pump repair, contact or HVAC contractors to receive support. Our technicians have the training necessary to fix your broken heat pump system.
Boiler Installation and Repair Services
Another popular heating system, boilers are a great energy-efficient way to heat your home. We offer HVAC installation, repair, maintenance, and tune-ups on boilers.
If you notice any of the following signs, contact us for boiler repair:
- Insufficient heat
- Foul odors
- Strange noises
- Cold air
- Yellow pilot light
We also offer routine boiler maintenance to expand the longevity of your system and ensure it is fully functional when you need it.
Thermostat Installation, Replacement, and Repair Services
Your thermostat is the remote control for your climate comfort. It controls heating and cooling functions but is often one of the most overlooked components of your HVAC system.
If you begin noticing malfunctions in your HVAC system, before rushing to assumptions that a motor is broken or you need a full replacement, consider your thermostat. We offer thermostat installation, replacement, and repair services.
Commercial Heating Maintenance and Replacement Services
Just like homes, businesses and commercial spaces need to offer a good climate-controlled environment to keep patrons and employees alike comfortable.
If you notice anything off about your business’s HVAC system, call the professionals at Theilmann to receive fast and convenient commercial heating repairs and services. Our 90 years of expertise means we’ve seen it all, not just in residential spaces but in commercial ones as well.
Professional Plumbing Services in Waukesha WI
Thielmann Heating, Cooling, and Plumbing has been serving Waukesha homeowners for over 90 years. Our licensed plumbers handle every type of plumbing issue with precision and care. From minor leaks to full system replacements, we provide clear solutions that keep your home running smoothly.
A plumbing issue can quickly disrupt your day. That’s why we respond quickly and get the job done right the first time. Our technicians inspect your system, identify the problem, and provide straightforward options that fit your needs and budget. We use trusted materials and proven methods to ensure repairs last.
We offer a full range of plumbing services in Waukesha:
- Drain & Sewer Cleaning: Clear out blockages and buildup to restore smooth water flow and prevent future clogs.
- Fixture Repair & Installation: Replace or repair faucets, toilets, and sinks for improved performance and reduced water waste.
- Water Heater Repair & Replacement: Maintain, repair, or upgrade tank and tankless models for steady hot water and better efficiency.
- Water Treatment & Filtration: Remove hard minerals and impurities for cleaner, healthier water throughout your home.
- Water Line Repair & Replacement: Fix damaged pipes or install new water lines to maintain consistent pressure and prevent leaks.
- Sump Pump Repair & Installation: Keep your basement safe from flooding with expert sump pump maintenance and installation.
Homeowners throughout Waukesha trust Thielmann Heating, Cooling, and Plumbing for honest work and dependable service. We take pride in our craftsmanship and commitment to customer satisfaction. When you need professional plumbing you can trust, call Thielmann today and let our experts take care of your home.

Take Back Your Weekends and Worry Less About Cooling and Heating Repairs in Your House
One of the advantages of working with our team of professionals includes having more time to enjoy your free time in Waukesha. While we take care of solving your HVAC problems, you can spend your time out on the town.
Take a stroll around Sanctuary Woods or visit the Waukesha County Historical Society and Museum. Our technicians will quickly inspect and fix your malfunctioning furnace or air conditioner to ensure you have time to enjoy your weekend.
Book a Heating or Cooling Appointment With Our Team in Waukesha
Our team in Waukesha is available any day for heating and cooling services. From boiler repair and heat pump installation to AC maintenance plans and heaters repairs, we have you covered. We also are skilled in air quality and offer duct cleaning, whole-home humidifiers, and other air purification services.
Simply fill out our form online or give us a call at (262) 315-3067 to receive assistance.
EXCELLENT Based on 542 reviews Posted on Stephanie DolnikOctober 10, 2024Trustindex verifies that the original source of the review is Google. Everyone that I have ever came into contact with there has been helpful and wonderful! I would recommend them to anyone!Posted on Aaron WilhelmJuly 19, 2024Trustindex verifies that the original source of the review is Google. Gave me a quote to replace my 29 year old air conditioner.They weren’t the cheapest but were priced with in reason. Installed it quickly and operates wonderfully. I couldn’t be happier.Posted on Lisa FarrellJuly 19, 2024Trustindex verifies that the original source of the review is Google. My husband and I received 5 quotes from 5 different companies before finally deciding upon Thielmann. Although Thielmann was a bit more expensive, the quality we received was outstanding. We went through the Costco Program (Lesa at Menomonee Falls) and received more rebates in doing so. With that program, we received 10% back on our Lennox Air Conditioner and Lennox Furnace. In addition, we received another 2% back by going through Costco and another 2% back by putting it on the Costco Visa card. At any rate, from, Jason, who came to our house to explain what would be done and provide the estimate, to the installers, Ben and Hayden, who provided excellent care installing our new products. They spent the entire day replacing our new HVAC system. The guys were extremely professional and had great precision. Thank you, Thielmann, for a wonderful HVAC system, great customer service, and an amazing job!Posted on Dave SeefeldtJuly 19, 2024Trustindex verifies that the original source of the review is Google. Professional and fast! Installation looks great!Posted on De'Angelo TatumJuly 15, 2024Trustindex verifies that the original source of the review is Google. I liked my experience with them. The guys I spoke with prior to doing the work, the estimation phase , and the ones I spoke with after the work was completed had enough knowledge and suggestion to answer all my questions. I’m pleased with the job they did. I had two AC units installed.Posted on Jay OrcholskiJuly 14, 2024Trustindex verifies that the original source of the review is Google. Wayne helped us find the right equipment. Ben and Hyden were great with the install. Wonderful team, as I would highly recommend The Thielmann Group.Posted on Brad DeFauwJune 26, 2024Trustindex verifies that the original source of the review is Google. I recently had the pleasure of working with The Thielmann Group Heating & Air Conditioning to install a mini-split HVAC system for the second floor of our Cape Cod home in Cedarburg, WI, and I couldn't be more satisfied with the entire experience. Professionalism and Expertise: From the initial consultation to the final installation, the team at The Thielmann Group demonstrated exceptional professionalism and expertise. They took the time to thoroughly assess our home and understand our specific cooling needs. Their knowledgeable staff answered all our questions and provided valuable insights into the benefits of a mini-split system for our unique architectural setup. Quality Installation: The installation process was seamless and efficient. The technicians arrived on time, were courteous, and worked diligently to complete the installation with minimal disruption to our daily routine. They were meticulous in their work, ensuring that everything was installed correctly and neatly. I was particularly impressed with their attention to detail and their commitment to maintaining the aesthetic integrity of our home. Performance: The mini-split HVAC system has exceeded our expectations. The second floor, which used to be uncomfortably warm during the summer months, is now perfectly cool and comfortable. The system operates quietly and efficiently, providing consistent temperature control without any noticeable increase in our energy bills. The Thielmann Group's recommendation and installation of this system have significantly improved our home's overall comfort and livability. Customer Service: The customer service we received was outstanding. The Thielmann Group kept us informed throughout the entire process, from scheduling the installation to following up afterward to ensure everything was working properly. They genuinely cared about our satisfaction and went above and beyond to make sure we were happy with their service. Overall Experience: I highly recommend The Thielmann Group Heating & Air Conditioning to anyone in need of HVAC services. Their professionalism, expertise, and commitment to customer satisfaction are truly commendable. Our experience with them was nothing short of excellent, and we are thrilled with the results of our new mini-split HVAC system. Thank you, Thielmann Group, for your exceptional service and for making our home a more comfortable place to live!Posted on Gail EllenbeckerJune 22, 2024Trustindex verifies that the original source of the review is Google. Quick, through team
Recent Jobs and Reviews in Waukesha, WI
Waukesha, WI at a glance
Thielmann Heating, Cooling & Plumbing has completed 20 jobs in Waukesha, WI in October 2026.
The most recent job was on October 30, 2026.
Thielmann Heating, Cooling & Plumbing has completed 267 jobs in Waukesha, WI in the last 12 months.
Job Locations and Reviews
Completed installation of an R-454B air conditioning system, including line set routing through the exterior wall penetration with brazed copper connections and insulated suction line. Performed system commissioning with a digital manifold gauge and temperature clamps, verifying proper refrigerant charge, pressures, and operating temperatures at the outdoor condenser.
Installed a new furnace and air conditioning system with a new refrigerant line set, reusing the existing filter cabinet and thermostat, and adapted the condensate and venting connections to PVC. Replaced the existing gas water heater with a new 40-gallon unit, connecting gas, water, and venting with expansion tank in place. Work was completed under permit with licensed electrical connections, and the system was started up and verified for proper operation.
Performed a tune-up inspection on the furnace/air handler and measured electrical load with a clamp meter. Used a borescope to inspect the evaporator coil and found heavy frost/ice buildup, indicating restricted airflow or a refrigerant-related fault. Recommend further diagnosis of the iced evaporator coil, including airflow and refrigerant charge evaluation, to restore proper system operation.
Performed an on-site estimate for replacing the existing air conditioner with a heat pump system, with the functioning furnace retained as backup heat in a dual-fuel configuration. Inspected the main electrical service, noting a main breaker panel with an adjacent sub panel and a PV solar breaker, and documented the panels to verify available capacity and compatibility for the new equipment.
Conducted an on-site fixture estimate for the installation of a new bathroom faucet and toilet. Inspected the existing two-piece toilet and the single-handle chrome faucet on the drop-in vanity sink, finding both in clean condition with no visible cracks, staining, or corrosion, and documented the fixtures and surrounding area (vinyl flooring, baseboard trim, and countertop layout) to determine installation requirements.
Performed a scheduled pre-paid furnace tune-up on a Daikin gas furnace under the recurring membership agreement. Inspected the unit and connected condensate/PVC venting, and verified electrical operation with a True RMS clamp multimeter, taking amperage and voltage readings. No frost, ice, rust, or cracks were observed on the equipment, and the furnace was left operating normally with service labels in place on the plenum.
Arrived within the scheduled window to evaluate the existing oil-fired boiler system for replacement. Inspected the basement mechanical room, including the boiler, flue piping, circulator pumps, expansion tank, copper piping manifold, and adjacent electrical panel and standby generator, and documented existing conditions with photos. Reviewed replacement options and provided an estimate for boiler replacement.
Performed a diagnostic inspection of the hydronic boiler and associated piping, circulator, expansion tank, and controls. Found heavy verdigris corrosion on copper piping, valves, and fittings, along with rust and corrosion at the threaded connections of the aquastat/control assembly, and dust and debris buildup on the gauge and controls. Documented all findings with photos and recommend repair or replacement of the corroded components to prevent leaks and ensure reliable boiler operation.
Responded to a reported drain backup at the kitchen sink, where wastewater from the garbage disposal was surfacing in the adjacent basin and leaking from the under-sink drain piping. Inspected the disposal discharge, PVC slip-joint connections, and P-trap assembly, then cleared the obstruction in the drain line and re-secured the slip-nut couplings to eliminate the leak. Confirmed proper drainage and a leak-free drain assembly after reassembly and flow testing.
Inspected the leaking bath spout and accessed the plumbing supply assembly within the wall cavity, where aged brass fittings and galvanized steel piping showed corrosion, mineral scale, and oxidation at the threaded connections. Evaluated the tub drain and overflow assembly, noting rust staining around the drain stopper, and addressed the leak at the spout to restore proper operation.
Responded to a no-heat call on a 10+ year old furnace and inspected the control circuit, finding the integrated furnace control board (EVCON) with visible residue, corrosion, and contamination around the power resistors and solder joints, causing the unit to fail to initiate a heat cycle. Diagnosed the control board as failed and in need of replacement, and documented the board and cabinet condition, which showed general dust and debris buildup throughout the blower compartment.
Responded to an emergency sump pump failure and performed on-site diagnostics of the sump system, including the pit, discharge piping, and electrical connections. Inspected the Schedule 40 PVC discharge assembly with flexible rubber coupling and union fittings, confirmed the cleanout and surrounding plumbing were intact, and noted surface corrosion on the sump pit cover. Prepared a replacement estimate for the sump pump to restore reliable water removal and protect the basement from flooding.
Installed a customer-supplied freestanding laundry tray and faucet, setting the tray on concrete blocks and connecting the faucet to new copper hot and cold supply lines secured with strut brackets and terminated at shutoff valves. Tied the tray's drain into the existing PVC drain piping and confirmed the connections were secure and the fixture was ready for use.
Performed an in-home furnace replacement evaluation on a 22-year-old unit (customer-reported age, which supersedes the equipment record on file). Inspected the thermostat and the supply and return ductwork, with the sheet metal trunk lines and transitions showing no visible rust, frost, or damage. Documented the existing system conditions with photos to support replacement equipment recommendations.
Performed a furnace tune-up, inspecting the burner assembly, gas valve, inducer motor, and control board wiring, and confirmed proper ignition with a stable blue flame. Verified the condensate drain, PVC vent piping, and flue connections were intact, and checked the surrounding ductwork and equipment area for obstructions or damage. System operating normally at completion.
Performed a seasonal HVAC tune-up and inspection on the furnace/air handler, including verification of the condensate drain piping, ductwork connections, control wiring, and thermostat. Conducted a 10-minute pressure test using a digital manometer (testo 510i), recording a stable reading of 0.50 inH₂O. Updated the unit's service log with the completed maintenance.
Diagnosed a leaking faucet and removed the valve cartridge, which showed heavy mineral buildup, corrosion, and worn O-rings that were causing the leak. Disassembled the fixture using pliers and a screwdriver, and inspected the stem and fittings for wear and debris.
Performed a seasonal tune-up on a Daikin gas furnace with an upper evaporator coil cabinet, inspecting the condensate drain piping, PVC vent/intake connections, gas supply line, refrigerant line set insulation, and electrical conduit connections. All components were found in serviceable condition with no signs of frost, rust, leaks, or visible damage, and the unit was left operating normally.
Replaced the outdoor condenser fan motor under manufacturer warranty on the Lennox unit, installing the new motor and fan blade assembly and reconnecting the wiring per the supplied wiring diagram. Verified the fan guard was secured and the unit was free of rust, frost, or damage.
Responded to a customer complaint of rattling noise from the Daikin furnace and performed a full inspection of the unit, including the cabinet, venting, and PVC flue/intake piping connections. No abnormal noises or operational faults were identified during testing, and the system was found to be operating within normal parameters.