Heat-ready control junction box for Coleman Mach 8530, 9530, 7530, 8630, 9330, and 6797 Series ceiling assemblies. Supports cooling and optional electric heat strip operation. Compatible with non-ducted and ducted installations.
The Coleman Mach 8530-5091 is the OEM replacement control junction box assembly for a broad range of compatible 8000 and 9000 Series ceiling assemblies. The control junction box is the central relay housing mounted inside the ceiling plenum — it receives low-voltage signals from the wall thermostat and uses those signals to switch 115 VAC power to the rooftop unit's compressor, fan motors, and optional electric heat strip. Without a functioning control box, the AC system cannot respond to thermostat commands.
The 8530-5091 is a heat-ready control box, meaning it supports both cooling operation and optional electric heat strip operation. If the existing ceiling assembly was previously cool-only, installing the 8530-5091 enables heat strip capability — though the heat strip itself must be purchased and installed separately. The control box operates on a 12 VDC low-voltage thermostat circuit and switches 115 VAC loads through its internal relays.
This kit is compatible with non-ducted and ducted ceiling assembly configurations. It includes an evaporator freeze control sensor, which monitors evaporator coil temperature and opens the compressor circuit if coil temperature drops dangerously low — protecting the system from freeze-up under restricted airflow conditions.
Supports both cool-only and electric heat strip operation — enables heat strip capability even on previously cool-only installations
Compatible with both non-ducted ceiling assemblies and ducted plenum configurations across supported model series
Evaporator freeze control sensor included — protects the compressor circuit from coil freeze-up under reduced airflow conditions
Backed by a 2-year limited manufacturer's warranty — longer coverage than many comparable Coleman Mach control box parts
(1) Control Junction Box Assembly — the relay housing that mounts in the ceiling plenum and switches 115 VAC to the rooftop unit based on 12 VDC thermostat signals (1) Evaporator Freeze Control Sensor — connects to the FREEZE terminal in the control box; opens the compressor circuit at 28°F and resets at 55°F to prevent coil freeze-up Note: Electric heat strip is not included. If adding heat strip capability to a previously cool-only installation, the heat strip assembly must be purchased separately.
The wall thermostat sends 12 VDC signals to the control junction box mounted inside the ceiling plenum. The control box uses these low-voltage signals to energize internal relays, which in turn switch the 115 VAC supply to the rooftop unit's compressor, high fan, low fan, and — when a heat strip is installed — the heat strip circuit. The 8530-5091 is a heat-ready assembly, meaning the relay and wiring provisions for electric heat strip operation are already built in. To add heat strip heating, install a compatible heat strip assembly (sold separately) and connect it to the heat strip terminal on this control box.
The 8530-5091 is designed for ceiling assembly models 8530, 9530, 7530, 8630, 9330, and 6797 Series. A separate control box, the 8330-5571, fits a different group of ceiling assemblies using sensor wire leads with connectors. Verify your ceiling assembly model series before ordering to ensure the correct control box type for your installation.
Coleman Mach control junction boxes are specific to ceiling assembly model series and connector type. This table summarizes key options to help identify the correct replacement for your system.