Fitting air conditioning to a Stag

By Vic Farrington. His full write-up, wiring diagram and installation photos are in Downloads.

Air conditioning was a factory option on the Stag until early 1974, and very few cars in Australia have it. Vic fitted his own, and it made the car far more usable in summer, with no cooling problems on days over 40 °C.

The approach

• Original evaporator and heater unit from a US-market Stag, reconditioned. It fits the car with almost no changes to the interior, though good units are scarce and not cheap.
• Modern compressor and condenser running R134a. The original York compressor can't be used with modern refrigerants, and the modern parts are more efficient.
• Condenser and two 10 inch thermo fans mounted in front of the radiator on fabricated brackets, with heat-resistant foam so the air goes through both cores.
• Compressor bracket made from wrecking yard brackets (mainly a mid-80s Falcon one) on a universal mount, bolted to the original mounting points and braced against the pulley load.
• Electrics using three relays: radiator fan, A/C fan and compressor clutch, and a relay that runs the radiator fan whenever the A/C is on, with a thermostatic switch and a manual override.

Things that caught him out

• The original heater valve works in reverse to modern ones, and on the Stag the heater and A/C flap share one control. He reversed a compact Commodore and Falcon valve to suit, and suggests a separate heater control instead.
• The condenser and fan assembly won't go in through the grille. It goes in from the engine bay with the radiator out.
• The modern compressor sits further forward, so the overflow bottle has to move.

Before you start: get the cooling system right first. A/C adds heat in front of the radiator.

Questions about this conversion? Ask in Tech Q&A.