2.3 HVAC System¶

Overview¶

Custom Restomod Air electronic HVAC system (on order) replaces the factory 2005 TJ HVAC.¹ Restomod Air kits are fully electronic — mode and blend doors are servo-driven from the control head — so the factory vacuum mode doors, cable blend door, and dash control panel are all deleted.² This removes the build's only vacuum consumer: no vacuum supply from the R2.8 is required (the diesel makes minimal manifold vacuum anyway, and braking is already vacuum-independent — see iBooster).

PMU Integration¶

See PMU Outputs for complete configuration.

A/C Request Circuit (PMU In 9)¶

The Restomod Air control head generates the A/C request: when A/C is commanded, its compressor-engage output goes to 12V. That output routes through the kit's trinary pressure switch (30 psi low-pressure cutout, 406 psi high-pressure cutout)³ and then to PMU In 9, so the PMU only sees a request when refrigerant pressure is in the safe range. PMU logic then drives OUT17 → compressor clutch.

The trinary switch's third function (electric fan request at 254 psi) is not wired — radiator fan control is handled by the dedicated fan controller with its own coolant sensor (see Radiator Fan); revisit only if condenser airflow proves insufficient.

R2.8 ECM A/C Integration¶

The CM2220 ECM used by the R2.8 has no A/C request input pin, so PMU-to-ECM A/C signaling is not applicable for this build. A/C clutch engagement may cause a slight idle dip but not enough to require compensation.

Outstanding Items¶

Related Documentation¶

• PMU Outputs - OUT5 and OUT17 configuration
• PMU Inputs - In 9 A/C request
• iBooster - Vacuum-independent braking (no engine vacuum used anywhere in the build)
• Radiator Fan - Fan control (independent of A/C trinary fan signal)