Coleman-Mach ChillGrille Straight Through Ducted Plenum Kit Installation Instructions

1. Warnings

Important Notice

These instructions are for qualified individuals trained and experienced in the installation of this equipment and related system components. Installation and service personnel may be required to be licensed in some states. Persons not qualified shall not service this equipment.

Warning

Improper installation may damage equipment, create a hazard, and void the warranty. Using components not tested in combination with these units will void the warranty, may violate state codes, create a hazard, and damage the equipment.

Warning – Shock Hazard

To prevent severe personal injury or equipment damage due to electrical shock, always ensure the electrical power to the appliance is disconnected during installation. Carefully follow all instructions and warnings in this booklet to avoid damage to the equipment, personal injury, or fire.

Note on Terminology

The words "Shall" or "Must" indicate a requirement essential for satisfactory and safe product performance. The words "Should" or "May" indicate a recommendation that is useful or helpful but not essential.

2. Package Contents

Chillgrille Assembly Consists of:

• 1) Chute/Supply Air Plate
• 1) Shroud Assembly
• 2) Filters
• 2) Grilles

Other Components:

• 1) Forward Supply Duct
• 1) Duct Seal Strip
• 1) Duct Divider Board
• 1) Divider Board Gasket
• 1) Mount Frame
• 1) Small Parts Package Consisting Of:
• 4 - Bolts
• 10 - Screws - 3/8" Length
• 4 - Springs
• 4 - Washers

3. General Information and Requirements

The flush mount ceiling plenum is designed for systems using field-fabricated (OEM supplied) cold air ducting routed through the ceiling cavity. Ducting specifications are detailed in the "Supply Ducting and Registers" section.

The system uses a single, non-ducted, centrally located return air opening within the ceiling plenum. The plenum must be positioned directly below the roof opening for the rooftop unit.

Manual controls are replaced by control relays mounted in the ceiling plenum's electrical box. These relays have 12 VDC coils, energized by a wall thermostat, and control the 115 VAC power to the rooftop unit.

A low voltage controller manages all air conditioning functions, using a 12 VDC circuit to energize the ceiling plenum relays. This controller can be a combination (Heat/Cool) unit and operate both the rooftop air conditioner and furnaces with a 12 VDC control circuit (1 amp or less).

Air conditioning equipment is susceptible to freeze-up if evaporator airflow is reduced. To prevent this, a low-temperature probe monitors the evaporator coil temperature. If it drops below 28°F (-2.2°C), the switch opens, stopping compressor operation. Operation resumes when the coil warms to 55°F (12.8°C).

Important Note on Freeze Sensor

The low-temperature sensor is part of the ceiling plenum electrical circuit. The probe must be inserted into the evaporator coil of the rooftop unit by the installer when bolting the ceiling plenum to the unit.

4. Ceiling Plenum Installation Requirement

1. The ceiling plenum must be installed under the roof opening. It bolts below the rooftop unit, with the framed ceiling cavity compressed between the two components for stability.
2. Ceiling cavity depth (distance from ceiling to roof) should be a maximum of 5 inches.
3. A divider board is provided to separate conditioned air from return air supply.
4. The 115 VAC service for the rooftop unit must be routed into the ceiling plenum. Route the 115 VAC supply wiring into the front of the roof opening to prevent wire pinching and ease installation.
5. The wirebox has a 9-pin receptacle that mates with the rooftop unit's 115-volt electrical conduit. Ensure plugs are properly aligned and snapped securely.
6. Heat/cool units have a two-pin receptacle for the heater assembly's umbilical plug.
7. Low Voltage Control Wiring (Wall Thermostat):
   • A low-voltage terminal strip on the front of the box connects to control wires via 1/4" quick connects.
   • Low-voltage control wiring must run from the thermostat location to the wirebox terminals. Route wiring into the front of the opening to prevent pinching.

5. Control Box Kits

Standard Control Box Wiring Functions

Zone Control Box Wiring Functions

* Zone 1 has the option of using the thermostat as a room sensor.

Control Box Kits Details:

1. 8330-752 – 12 VDC Controlled, Cool Only

This kit includes a control box assembly. The evaporator freeze sensor is shipped separately for installation via quick connects to the "Freeze" terminal strip.

2. 9330C755 – 12 VDC Controlled, Heat Ready

This kit includes a control box assembly. The evaporator freeze sensor is shipped separately. The heater assembly for 47000 series units is 47233*4551. For 48000 and 49000 series units, the heater assembly is 9233*4551. These heater assemblies are purchased separately.

3. 8530-750 – 24 VAC Controlled, Cool Only

This kit is similar to the 8330-752 but includes a transformer attached to the box assembly.

4. 9530A751 – 12 VDC Controlled, Heat Pump

This kit is similar to the 9330C755 but is wired for heat pump functionality.

6. Control Box Kits (Zone)

1. 9430A751 – 12 VDC Zone Controlled, Cool Only

This kit includes a control box assembly. The evaporator freeze sensor is shipped separately for installation via quick connects to the "FREEZE" terminal strip.

2. 9430A755 – 12 VDC Controlled, Heat Ready

This kit includes a control box. The evaporator freeze sensor is shipped separately. The heater assembly for 47000 series units is 47233*4551. The heater assembly for 48000 and 49000 series units is 9233*4551. These are purchased separately.

3. 9630A751 – 12 VDC Zone Controlled, Heat Pump

This kit includes a control box assembly. The evaporator freeze sensor is shipped separately. Backup electric heat is available as an optional kit. The heater assembly for 47000 series units is 47233*4551. The heater assembly for 48000 and 49000 series units is 9233*4551. These are purchased separately.

7. Wall Thermostats

1. Locate and install the thermostat according to the instructions provided with the thermostat.
2. For 12 VDC thermostats, the 12-volt negative connection must be routed directly from the converter or battery. It is highly recommended to provide 12-volt control power from the battery side of the converter to prevent control issues.
3. For 24 VAC thermostats, if the application involves operation while in motion or subject to vibration, an electromechanical thermostat should not be used, as its contacts may "chatter" the compressor relay. For vibration-prone applications, an electronic wall thermostat is required. Airxcel, Inc. part numbers for suitable electronic thermostats are 8330B3241 or 7330B3441.
4. The sub-base used with heat/cool and heat pump thermostats replaces the standard mount plate. The thermostat body snaps onto the sub-base.

8. Supply Ducting and Registers

A. Ducting

1. Field-fabricated supply ducting must connect to both ends of the ceiling plenum. Two ducts are required: one to the front and one to the rear of the plenum (refer to Figure 1).
2. Each duct must have a minimum height of 1 3/4 inches and a maximum height of 2 1/2 inches. The total free area inside each duct must be at least 10 square inches.
3. When ducting connects to the ceiling plenum, the maximum width is 6 inches.
4. All field-fabricated cold air supply ducting must be insulated and have a vapor barrier.

Note: To reduce restriction and improve airflow, minimize bends and turns in ducting. Radius any required corners.

A minimum of 10 square inches of free area per duct is recommended; larger ducting improves airflow and system performance.

Important: Insulation reduces cooling loss and helps prevent water staining on the vehicle ceiling due to condensation.

B. Registers

Supply (cold air) registers should have a minimum discharge area of 48 square inches per system, or 24 square inches per duct. A minimum of 6 registers is recommended.

9. Routing Thermostat Wiring

1. Determine thermostat mounting location per instructions provided with the thermostat.
2. Follow Airxcel, Inc. low voltage wiring specifications and all applicable local and national electrical codes:
   • A. Route the thermostat 12 VDC supply wiring from the power source to the mounting location. Two wires are required: a +12 VDC lead (red) and a -12 VDC lead (blue).
   • B. A 2-amp fuse is provided with the thermostat to protect it from over-current damage.
   • C. Route the thermostat control wiring from the mounting location into the front of the ceiling plenum opening. Four wires are required for cool-only boxes (five for heat/cool boxes). These wires are: Blue (-12 VDC), Yellow (compressor), Green (high fan), Gray (low fan), and White (heat, if applicable).
3. Airxcel, Inc. low voltage wiring specifications:
   • A. All low voltage wiring should be a minimum of 18 gauge.
   • B. Low voltage wiring must be routed into the front side of the ceiling plenum opening.

10. Routing Thermostat Wiring (Zone)

1. Determine thermostat mounting location per instructions provided with the thermostat.
2. Follow Airxcel, Inc. low voltage wiring specifications and all applicable local and national electrical codes:
   • A. Route the thermostat control wiring from the mounting location into the front of the ceiling plenum opening.
   • B. Refer to Figure 5 for wiring requirements for multiple zones.
   • C. These wires include: Red (+12 VDC), Blue (-12 VDC), Purple (Sig 1), Black (Sig 2), and optional wires for auto generator start (Gen), room temperature sensor, heating appliance control (up to 4), and load shed (cool/heat).
3. Airxcel, Inc. low voltage wiring specifications:
   • A. All low voltage wiring should be no smaller than 18 gauge.
   • B. Low voltage wiring must be routed into the front side of the ceiling plenum opening.
   • C. Low voltage wiring should not be routed with high voltage wiring.
   • D. If low voltage and high voltage wires must cross, they should do so at right angles.

11. Routing 115 VAC Wiring

Follow Airxcel, Inc. high voltage wiring specifications and all applicable local and national electrical codes to route the rooftop unit's 115 VAC supply wiring from its power source to the wirebox.

High Voltage Wiring Specifications based on Minimum Overcurrent Protection Device Amperage:

1. U.L. requires copper conductors only with a minimum #12 AWG when using the minimum recommended overcurrent protection device. Higher rated devices or longer wiring runs require #10 AWG or greater copper conductors.
2. To prevent voltage drops greater than 10% during starting loads, use #10 AWG or larger copper conductors for lengths over 50 feet. Match conductors to the overcurrent protection device.

Circuit Protection: Refer to the upper unit nameplate.

Higher Voltage Wiring Specifications based on Overcurrent Protection Device rated higher than the minimum required:

Follow all local and NEC (National Electrical Code) guidelines for proper wire sizing (AWG) based on the selected Overcurrent Protection Device and the length of the wiring run to the air conditioner.

Figure 1 depicts the components involved in the ceiling plenum installation, including the rooftop unit, roof opening, supply duct, duct seal, mount frame, springs, bolts, washers, duct divider, foam strip, chute/supply air plate, shroud assembly, filters, and return air grilles.

12. Ceiling Plenum Mounting

1. Place the air conditioner over the roof opening (refer to Figure 1).
2. The duct divider is pre-cut to conform to the supply duct. The attached foam accommodates widths between 14" and 15". Measure the distance between the ceiling and the basepan, subtract ½ inch, and cut the divider height accordingly, trimming excess from the top (refer to Figure 1).
3. Install the adhesive-backed foam strip onto the top edge of the duct divider. Wedge the divider between the roof opening walls and against the upper unit basepan to create an insulated, vapor-sealed barrier between supply and return air. The divider board should fit snugly.
4. Insert the forward supply duct assembly into the divider board cutout, easing it forward until the flange contacts the front edge of the roof opening.
5. Align the bottom of the supply duct with the duct opening. Secure the duct with two provided screws. Use the duct seal from the mount kit to seal any gap at the bottom of the duct flange where it meets the bottom ceiling duct opening (refer to Figure 1).
6. Install the ceiling assembly mount frame using the four bolts, washers, and springs (refer to Figure 1). Tighten until the spring coils achieve closure.

13. Installing the Control Box

1. Remove the control box assembly cover (held by two sheet metal screws). Feed field lead wires and ground through the strain relief.
2. Connect the black supply conductor to the black "pigtail" lead, white to white, and ground to green using the provided wire nuts.
3. Ensure no bare wires contact live electrical parts or become pinched between the control box sides and lid. Insert the strain relief into the control box entry hole to secure field wiring. Reinstall the control box lid.
4. Attach thermostat wires to the control box per the following illustrations:
   • A. Control Box 8330-752: Shows connections for High Speed Fan (Green), Low Speed Fan (Gray), Compressor (Yellow), Heat (White), and -12 VDC (Blue).
   • B. Control Box 9330C755, 9530A751: Shows connections for High Speed Fan (Green), Low Speed Fan (Gray), Compressor (Yellow), Heat (White), -12 VDC (Blue), and Evaporator Freeze Sensor.
   • C. Control Box 8530-750: Shows connections for Fan (Green), Compressor (Yellow), Freeze Sensor, -12 VDC (Blue), and 24 VAC Power to Thermostat.
5. Connect the rooftop unit's 115-volt electrical conduit to the wirebox 9-pin receptacle, verifying proper alignment and secure connection.
6. Locate the two machine screws inside the evaporator cover of the upper unit. Align the control box over these screws and secure it using the supplied wing nuts. For 47000 series units, refer to Figure 8.
7. Insert the evaporator freeze sensor between the evaporator fins near the bottom center, between the bottom two tubes (refer to Figure 2). Insert straight until contacting the staggered tube behind the insertion point. Once contact is made, elevate the exposed sensor end approximately 45 degrees, then continue insertion at a 45-degree angle until fully embedded in the evaporator.

Figure 2 illustrates the placement of the evaporator freeze sensor within the evaporator coil.

14. Installing the Control Box (Zone)

1. Remove the control box assembly cover (held by two sheet metal screws).
2. Set the "zone" jumper to the correct zone position for the air conditioner or heat pump's location in the coach (Zone 1 is typically at the front).
3. Set the "HP"/"NON HP" jumper to "HP" for heat pumps or "NON HP" for other units.
4. Feed field lead wires and ground through the strain relief and then through the 7/8" hole in the side of the box.
5. Connect the black field power conductor to the stripped black 12-gauge wire in the control box.
6. Connect the white field power conductor to the stripped white 12-gauge wire in the control box.
7. Connect the ground field power conductor to the stripped green ground wire in the control box.
8. Ensure no bare wires contact live electrical parts or become pinched. Insert the strain relief into the control box entry hole to secure field wiring. Reinstall the control box lid.
9. Attach thermostat wires to the Zone 1 control box per the illustration (refer to Figure 4).

Figure 3 shows the zone and HP/NON HP jumpers. Figure 4 illustrates the wiring for the Zone 1 control box, detailing connections for communication signals (Purple, Black), -12VDC (Blue), optional auto generator start, freeze sensor, room sensor, and load shed devices, along with power inputs (Red for +12VDC).

Zone 2 is wired by jumpering from Sig 1, Sig 2, B-, and R+ on the Zone 1 box to the Zone 2 box. Zone 3 is wired similarly from Zone 2 to Zone 3, and Zone 4 from Zone 3 to Zone 4 (refer to Figure 5).

Figure 5 provides a detailed wiring diagram for multiple zone thermostats, showing connections between zone control boxes, thermostats, sensors, and power sources.

10. Connect the rooftop unit's 115-volt electrical conduit to the wirebox 9-pin receptacle, verifying proper alignment and secure connection.
11. Position the control box over the screws and secure it to the upper unit enclosure using the supplied wing nuts. For 47000 series units, refer to Figure 8.
12. Insert the evaporator freeze sensor between evaporator fins near the bottom center, between the bottom two tubes (refer to Figure 2). Insert straight until contacting the staggered tube behind the insertion point. Once contact is made, elevate the exposed sensor end approximately 45 degrees, then continue insertion at a 45-degree angle until fully embedded in the evaporator.
13. Connect the 115 VAC supply wiring to its power source. Ensure all power remains off until the checkout procedure begins.

DANGER

TO PREVENT THE POSSIBILITY OF SHOCK INJURY FROM APPLIANCE OPERATION:

The white wire must be connected to neutral in the service box entrance, and the mechanical ground must be connected to a grounding lug in the service box or the motor generator compartment.

Figure 8 shows a cut-away view of the evaporator coil and control box.

15. Installing the Heater Assembly

1. If adding an electric heater, the assembly can now be installed.
2. For 48000 and 49000 series units, position the heater assembly into the return air opening as shown in Figure 7. Ensure the set screw is retracted sufficiently to allow installation over the basepan extrusion. The heater bracket must be installed between the basepan and the plastic drain pan (refer to Figure 6). Tighten the set screw to secure the assembly and prevent movement. 47000 series units mount using wing nuts as shown in Figure 9.
3. Insert the two-pin connector of the heater umbilical into the receptacle on the control box, ensuring the connector snap-locks into position.

Wiring Safety: Tie all wiring to ensure no contact with the heater or sharp edges. Be aware that high-velocity air will be encountered in this area.

Figure 6 illustrates the heater bracket installation. Figure 7 shows the heater assembly installation for 48000/49000 series units. Figure 9 shows the heater assembly mounting for 47000 series units.

16. Install Air Grille Assembly

1. Raise the chute/supply air plate to the mount frame, ensuring the plenum duct divider is positioned between the two ribs. Install the chute/supply air plate to the mount frame using the 4 provided screws (refer to Figure 1).
2. Temporarily remove the return air grilles and filters from the shroud assembly.
3. Raise the shroud assembly, nesting it properly with the chute/supply air plate, and attach it to the mount frame with the 4 provided screws.
4. Reinstall the filters and return air grilles into the shroud assembly.
5. Installation is now complete.