What Phillips & Temro makes

Phillips & Temro Industries (PTI) designs and manufactures thermal and electrical systems that keep engines and equipment running in hard conditions, both as an OEM supplier and through the aftermarket. The portfolio spans four core brands. Zerostart covers engine heating: block heaters, air-intake and electric immersion heaters, circulation engine heaters, oil-pan heaters, cordsets, and thermostats. Arctic Fox covers fuel and fluid warming, including in-line diesel fuel warmers, fuel-tank heaters, silicone heating pads, and coolant dams. Truflo, based in Tipton, England, makes engine and radiator cooling fans, one-piece molded fans, hybrid fans, and segmented metal fans for construction, power generation, and industrial HVAC. Idle Free Systems makes electric auxiliary power units (eAPUs) and power-inverter systems that let semi trucks run cab climate and accessories without idling.

PTI has also moved into electrification. It sells EV charging and cable-management products under the EVOCHARGE brand and markets battery heaters and coolant warming for new energy vehicles, positioning the century-old heating business against the shift from combustion engines. The company describes end-to-end engineering as a service: custom design, prototyping, testing, and system integration, plus contract manufacturing for outside customers. Its named end markets are trucking, automotive and light-duty trucks, off-road and industrial equipment, oil and gas, power generation, agriculture, marine, and power sports.

The customer base is split between building parts into OEM vehicle and equipment programs and selling replacement and winterization products through distribution. That dual model shows up in the company's own materials, which pitch both engineered systems for manufacturers and catalog products with a parts-lookup tool for the aftermarket.

Ownership and history

PTI traces its founding to 1920, when James B. Carter opened a manufacturing business in Winnipeg, Canada, building heating products to keep cars starting on cold Canadian mornings. In Minneapolis, a separate company was acquired and renamed the Phillips Manufacturing Company in 1945, later home to the Zerostart heater brand. Carter's firm became Carter Temro Ltd. and registered Temro as a product brand. The two operations began merging in 1961 under the Phillips & Temro Industries name. The company marked its 100th anniversary in 2020.

The company grew by acquisition. Truflo, founded in Tipton, England in 1962, was acquired in 2005, adding a European cooling-fan operation. PTI acquired Arctic Fox in 2013, Idle Free Systems in 2014, and Wolverine engine heaters and Belgium's Carlor Engineering in 2017. On the ownership side, Audax Group first invested in PTI in February 2012. In March 2015, Harbour Group, a privately held St. Louis operating company, acquired PTI from Audax; the deal was financed by GE Antares Capital and reported by PRNewswire and regional business press. PTI remains privately held under Harbour Group. In April 2025, the company named Jeff Spethmann as Chief Executive Officer, effective April 15; Spethmann previously led HydrogenPro's US subsidiary and was Senior Vice President for Industrial Products at Donaldson Company.

Because PTI is privately held, it does not publish audited financials. Third-party estimates place employment near 720 people and annual revenue in a roughly $250 million band, figures that should be read as estimates rather than reported numbers. The company operates manufacturing and distribution sites in the United States, Mexico, Belgium, the United Kingdom, and China.

Certifications and quality

PTI publishes quality-management registrations for five sites. Its Eden Prairie, Minnesota headquarters is registered to IATF 16949:2016, the automotive quality standard, along with ISO 14001:2015 for environmental management and ISO 27001:2022 for information security. The Tipton (West Midlands) UK plant holds IATF 16949:2016, ISO 14001:2015, and ISO 9001:2015. The Yizheng, China plant holds IATF 16949:2016 and ISO 9001:2015. The Sprimont, Belgium plant holds ISO 9001:2015, and the Delano, Minnesota Arctic Fox site holds ISO 9001:2015 and ISO 27001:2022. Multi-site IATF 16949 registration is the working baseline for a company supplying automotive OEM programs. Individual certificate dates are not posted on the certifications page, so currency here rests on the site listings rather than dated certificates.

Known customers

Most of PTI's OEM relationships are not disclosed as customer names. The strongest public evidence comes from supplier and quality awards the company itself lists, each of which names the granting manufacturer.

Hino, Cummins, and Toyota Canada also appear in PTI's published awards history (Hino quality and delivery awards through 2016, a 2017 Cummins Category Partner designation, and Toyota Canada Certified Vendor status 2016 to 2018). These are awards the company publishes about itself, so they document a supplier relationship without disclosing program volumes.

Sourcing evidence

PTI's US import record reads like a manufacturer's, not a reseller's: 446 sea shipments from January 2015 through June 2024, with the most recent recorded shipment on June 2, 2024. Around 21 foreign suppliers appear across the record. The single largest, PTI Engineered Engine Components in Yizheng, China, is PTI's own Chinese operation and accounts for 182 shipments of engine heaters, battery warmers, and heat exchangers, the signature of a company moving components between its own plants rather than buying finished goods.

Seven shown of about 21 recorded suppliers. Origin countries include China (the large majority), Hong Kong, Brazil, India, Finland, Sweden, and the United Kingdom. Customs-derived estimates put cumulative ocean shipping spend near $365,000 across the window, with cost data covering about 43% of shipments, an order-of-magnitude figure rather than an audited one.

Coverage caveats: these are US ocean-freight bill-of-lading records only. Air, truck, and rail movements do not appear, and neither does most cross-border trade with PTI's plants in Mexico, Belgium, and the UK. Some records name freight intermediaries rather than manufacturers, and product categories come from declared manifest codes, which are noisy. The record going quiet after June 2024 reflects the limits of ocean-freight visibility, not necessarily a change in the business. Absence of a record is not evidence of absence, a point worth keeping in mind for buyers weighing nearshoring and tariff exposure.

Frequently asked questions

What does Phillips & Temro Industries make?

Phillips & Temro makes thermal and electrical systems for engines and equipment: engine block and circulation heaters (Zerostart), diesel fuel and fluid warmers (Arctic Fox), industrial cooling fans (Truflo), and electric anti-idling auxiliary power units (Idle Free Systems). It also sells EV charging products under EVOCHARGE. The company serves both OEM manufacturers and the aftermarket across trucking, automotive, off-road, power generation, and oil and gas markets.

Who owns Phillips & Temro Industries?

Phillips & Temro is privately held and has been owned by Harbour Group, a St. Louis operating company, since March 2015. Harbour Group acquired it from Audax Group, which had first invested in 2012. The company was founded in 1920 and remains headquartered in Eden Prairie, Minnesota.

Where is Phillips & Temro Industries headquartered?

Phillips & Temro's global headquarters is at 9700 West 74th Street, Eden Prairie, Minnesota 55344. The company operates additional manufacturing and distribution sites in Delano, Minnesota; Saltillo, Mexico; Sprimont, Belgium; Tipton (West Midlands), United Kingdom; and Yizheng, China.

Who are Phillips & Temro's customers?

PTI supplies automotive and heavy-duty OEMs and the aftermarket. Its published supplier and quality awards document relationships with General Motors, Ford, Subaru, Paccar, Hino, Cummins, and Toyota Canada. Most program details are not disclosed, as is normal for a Tier 1 and Tier 2 components supplier.

What certifications does Phillips & Temro hold?

Phillips & Temro publishes quality registrations for five sites. Its Eden Prairie headquarters and its UK and China plants hold IATF 16949:2016, the automotive quality standard. Sites also hold ISO 9001:2015, ISO 14001:2015 environmental certification, and ISO 27001:2022 information-security certification, varying by location.

How big is Phillips & Temro Industries?

Phillips & Temro is a mid-sized global manufacturer. Because it is privately held, it does not publish audited figures; third-party estimates put employment near 720 people and annual revenue in a roughly $250 million band. It operates six manufacturing and distribution sites across the US, Mexico, Belgium, the UK, and China.

Last verified September 28, 2026. Is this your company? Request a correction.