Electronic Rust Protection for Air Conditioners
Salt air, humidity and coastal weather are hard on air conditioners, especially outdoor units near the coast, on high-rise balconies and in marine settings. The CAT Electronic Rust Protection System is designed to help reduce the rate of corrosion on the unit’s painted metal casing, as one part of corrosion management alongside coatings and regular cleaning. Designed and made in Australia since 1989, it’s backed by a 10-year product replacement guarantee.
★★★★★ “The system has performed over and above our expectation — no rust developing in 7 years, less than 100 metres from breaking ocean waves.”
Robert, Verified Owner, April 2026
Technical & Design Summary
The CAT module sends a low-voltage signal through coupler pads bonded to the unit’s metal casing. It has two output circuits, so the pads can be spread around the unit. CATIII systems run 2 to 8 pads, and the CATIII HD range runs 6 to 12 pads for larger plant such as chillers and generators. You can add pads later with expansion packs.
Why Choose CAT for your Air Conditioner
Coatings protect the surface until they’re chipped or worn. CAT works alongside them: the module runs around the clock, needs nothing reapplied, and is designed to help slow the electrochemical process that causes rust on the unit’s metal casing. It has been refined since 1989 and is used on air conditioners, chillers and generators around the Australian coast.
Works Alongside Coatings
CAT complements protective coatings and regular cleaning. Use it as one part of your corrosion management, not a replacement for either.
Nothing to Reapply
Once fitted, the module runs continuously. There’s nothing to spray, recoat or top up.
Easy Installation
No drilling or structural changes. It fits new or existing units with standard tools, and an electrician or HVAC technician can fit it for you.
Runs 24/7
The module runs silently around the clock, in every season, as long as it has power.
Environmentally Friendly
No chemicals, sprays or solvents, and no waste or emissions. The module draws a maximum of 25 mA.
Non-Interference
CAT runs independently of your air conditioner’s controls and electronics. It won’t disrupt onboard circuits, diagnostics or automated functions.
Technical Specifications
System Capabilities
- Runs on 12 V or 24 V DC
- Mains-powered units: use a 240 V AC to 12 V DC power supply, with its negative earthed to the unit’s metal body
- CATIII: 2 to 8 pads on one module (two output circuits)
- CATIII HD: 6 to 12 pads for larger units such as chillers and generators
- Add pads later with 2 Pad Expansion Packs
- Maximum draw 25 mA
What Our Customers Say
Verified ownerExcellent service & quick shipping. We also purchased the a 2 pad CAT electronic rust protection system 7 years ago to install in our ducted air conditioning condenser unit. The unit is located on the roof of our building, exposed to the weather elements less than 100 metres from breaking ocean waves on the east coast of Australia. The system has performed over and above our expectation with no rust developing during this time. The team from Coastal Air in Batemans Bay, NSW have been amazed there is no rust on the unit when they service it!
Our company is located on Mermaid Beach in the Gold Coast Queensland. During the last 6 years or so we have installed well over 100 CAT SYSTEM electronic rust control units on high rise outside air conditioners which operate from main power by way of a reducer from 240 to 13 volts. These air conditioners are exposed to salt air 24 hours a day.In all that time there has been only one failure, the air conditioner rusted because CAT SYSTEM connection was not switched on!At all times we have found Roe Marketing and CAT Systems Australia most professional to deal with, providing excellent service and marketing a high quality unit with a most satisfactory performance result.I have no hesitation in recommending CAT SYSTEM for vehicles and in particular units installed on our air conditioners for complete rust protection.
HVAC FAQs
Q: What is electronic rust protection?
A: It uses a low-voltage electronic signal to help reduce the rate of corrosion on painted metal. On an air conditioner, CAT is fitted to the unit’s metal casing and works alongside coatings and regular cleaning.
Q: How does CAT work?
A: The module sends a signal through coupler pads bonded to the casing. It’s designed to help slow the electrochemical process that causes rust.
Q: Is CAT expensive?
A: No. A system costs a small fraction of the price of a typical outdoor unit, and there’s nothing to reapply.
Q: Does CAT come with a guarantee?
A: Yes. Every CAT system has a written 10-year product replacement guarantee. Full terms are on the warranty card in the kit.
Q: What power does CAT need?
A: 12 V or 24 V DC. For mains-powered units, use a 240 V AC to 12 V DC power supply, with its negative earthed to the unit’s metal body. We sell suitable power supplies.
Q: Does CAT suit larger units?
A: Yes. CATIII systems run 2 to 8 pads, and the CATIII HD range runs 6 to 12 pads for larger plant such as chillers and generators.
Q: Can I fit CAT to a unit that already has rust?
A: CAT can’t repair existing rust. Treat and repaint rusted areas first, because CAT works best on painted, intact surfaces.
Q: Will CAT affect how my air conditioner runs?
A: No. It runs independently of the unit’s controls and electronics.
Q: Can I use CAT with protective coatings?
A: Yes. CAT is designed to complement coatings, not replace them.