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2.3 HVAC System

Type: Custom Electronic A/C + Heat System

Model: Restomod Air custom kit — configuration TBD #146 (confirm against order)

Manufacturer: Restomod Air

Mounting: Under-dash (replaces factory TJ HVAC assembly)

Power Source: PMU OUT5 (blower motor), OUT17 (A/C clutch)

Control: Restomod Air electronic control head

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

Circuit PMU Load Control Notes
Blower Motor OUT5 (25A) TBD #146 — verify kit blower draw ≤25A Auto (ignition ON) Blower speed controlled by Restomod Air control head, not PMU
A/C Clutch OUT17 (7A) 3-5A In 9 trigger Restomod Air control head compressor request → trinary switch → PMU In 9 (TBD #146 — verify wire ID against kit diagram on arrival)

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

🔴 Critical (2)

High (7)

📋 Medium (3)

  • Horn button → PMU In 1 wiring path through steering column (#152) — PMU In 1 (horn request) lists "steering wheel button" as its source, and the horn page puts the button on the steering-wheel PTT bracket — but no wire path, gauge, or connector is defined for how the button contact reaches PMU In 1 through/around the steering column. Street-legal item with an under-specified signal path.
  • iBooster Wiring Harness Selection (#105) — Select the Bosch iBooster (Gen 2) wiring harness: Tulay's Gen 2 universal (plug-and-play) vs EVcreate Gen 2 connector kit (DIY). Decision pending donor arrival and pigtail condition inspection. Tracked in the purchase tracker but was missing a TBD issue.
  • Axle Brake Flex Hose Length (#86) — DOT (FMVSS 106) braided-stainless extended-length flex at each axle - length blocked on axle + suspension selection (Section 10); size to full droop, do not cut until ride height fixed

🔍 Verify (5)

  • iBooster standby current spec (ignition-off test value) (#151) — The engine-systems testing checklist includes "Verify iBooster standby current within spec (ignition OFF)" but no standby-current spec value is documented anywhere (the brake-booster page does not state one). The test step cannot be completed as written.
  • WAIT-to-start lamp polarity: ECM Pin 35 active-low vs HDX input active-high (#150) — ECM Pin 35 (WAIT lamp, yellow) is active LOW (~0V when WAIT on, ~+12V off); the HDX indicator input is documented as active HIGH. If wired without resolving this, the cold-start indicator reads inverted — and the documented cold-start procedure depends entirely on watching the WAIT lamp.
  • Restomod Air HVAC integration — verify A/C request wiring to PMU In 9 + blower draw (#146) — The factory TJ HVAC is replaced by a custom Restomod Air electronic HVAC kit (ordered, owner-confirmed 2026-06-11) — this resolves the original "no A/C request source post-PCM-delete" gap. Restomod Air kits are fully electronic (servo-driven doors, no vacuum), and the control head generates the A/C request: compressor-engage output (12V) → trinary pressure switch (30/406 psi cutouts) → PMU In 9. PMU logic then drives OUT17 → compressor clutch.
  • AMOT 4261M 2.8″ intake air-path connection OD / reducer coupler to 2.125″ turbo inlet (#129) — The 4261M02 is a wafer butterfly valve that sleeves into a 2.8″ (71 mm) nominal intake duct; the AMOT datasheet (4261M_Air_Shutoff_Valve_0119rev2) publishes only nominal size (71 mm), bore (61 mm / 2.4″), and overall envelope — not the air-path spigot/wafer OD or clamp interface. The NPT thread in part number 4261M02A027-AA (actuator code 27) is the pneumatic control port, not the air path.
  • Grid Heater Current (#42) — Design value 80A - verify via element resistance measurement during installation (~0.15 ohm @ 12V).
  • 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)

  1. Owner confirmation, 2026-06-11 — custom kit ordered from restomodair.com. Model/configuration per order confirmation; update this page when the unit arrives. ↩

  2. Restomod Air product line is "fully electronic aftermarket a/c system kits" with electronic control heads (no vacuum actuation). restomodair.com, accessed 2026-06-11. ↩

  3. Restomod Air trinary switch: 30 psi low-pressure cutout, 406 psi high-pressure cutout, electric fan signal at 254 psi. restomodair.com/support/trinary-switch/, accessed 2026-06-11. ↩