Load
Review how the AUTOTERM Air 2D 12V connects, how it operates and which installation requirements apply to this model.
Open this example as a new project. Use your own parts and cable lengths to make the plan yours.
The heater's running power does not establish its startup demand. Follow the supplied harness and its protection on both supply legs; preserve power for the controlled shutdown cycle. This page does not calculate a replacement heater supply circuit.
The heater's running power does not establish its startup demand. Follow the supplied harness and its protection on both supply legs; preserve power for the controlled shutdown cycle. This page does not calculate a replacement heater supply circuit.
Wiring diagram
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Installation notes
Guidance for this model, with sources linked beside the relevant advice.
Verified against the manufacturer's documentation (rev. AIR installation manual v01.2025, September 2025), checked 2026-10-01. Manufacturer documentation →
This is the 12 V diesel AUTOTERM Air 2D, including its supplied electrical harness. The technical table, page 32, distinguishes the 12 V and 24 V versions. Its 0.8–2 kW figure is delivered heat; electrical running power is 10–29 W. The catalog uses 29 W / 12 V, approximately 2.42 A, for the upper running load. The reviewed manual does not quantify glow-plug startup current, so the energy estimate does not establish startup cable sizing.
The positive and negative terminals represent the battery end of the supplied loom. The AIR-2D-12 diagram, page 38, shows 25 A fuses in both the red positive and black return legs. Retain that harness arrangement; do not replace it with a generic two-wire running-current circuit. The catalog's 25 A terminal boundary describes this protected harness, not the heater's consumption or an independently verified connector rating. The controller, temperature sensing and pulsed fuel-pump wiring remain on their dedicated loom connectors.
The electrical installation, page 20, calls for protected, dry routing and recommends a direct battery connection. Remove fuses while making connections and inspect the full circuit before restoring power. Avoid a switch or battery disconnect that removes the feed while the heater is running.
Use the manual's combustion-air, exhaust, fuel and heated-air layouts together. Combustion exhaust must remain outside occupied space and clear of air intakes; the cabin-air intake must not draw exhaust from an engine compartment. Check hose orientation, mounting clearances and the specific vehicle or boat installation requirements before drilling. Electrical completion alone does not make a heater installation ready to use.
Stop the heater with its controller and let the automatic purge finish before isolating battery power. For starting failures, measure voltage at the heater during the attempt and inspect both fused supply legs before replacing parts. The service guidance, page 27, calls for inspection of corrosion, fuel and exhaust connections and a monthly full-power run of about 20 minutes. The same page gives 30–40 mA standby consumption; account for that separately during long storage.
Build it out
Add Air 2D 12V to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
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pos
positive · input
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neg
negative · input
Method & provenance
Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.