Dometic Roof Top Air Conditioner

Introduction

This air conditioner, referred to as "unit" or "product", is designed for installation on the roof of a Recreational Vehicle (RV). It can be installed by one person with assistance. These instructions ensure proper installation and function. Dometic Corporation reserves the right to modify specifications without notice.

Important Safety Instructions

This section provides safety information to reduce the risk of accidents and injuries.

Recognize Safety Information

[i] The safety alert symbol [!] alerts to potential physical injury hazards. Obey all safety messages following this symbol to avoid injury or death.

Understand Signal Words

Signal words indicate hazard seriousness:

• WARNING: Hazardous situation, if not avoided, could result in death or serious injury.
• CAUTION: Hazardous situation, if not avoided, could result in minor or moderate injury.
• NOTICE: Practices NOT related to physical injury.

Supplemental Directives

[!] Read and follow all safety information and instructions to avoid injury or death. Understand these instructions before installing, using, servicing, or performing maintenance. Incorrect procedures can lead to serious injury.

Compliance

Installation must comply with applicable local and national codes, including:

• U.S.A.: ANSI/NFPA70 (NEC), ANSI/NFPA 1192 (Recreational Vehicles Code)
• Canada: CSA C22.1, Parts I & II (Canadian Electrical Code), CSA Z240 RV Series (Recreational Vehicles)

General Safety Messages

WARNING: Failure to obey these warnings could result in death or serious injury:

• Installation/servicing must be done by a qualified service technician.
• Do NOT modify the product; modification is hazardous.
• Do NOT add unauthorized devices or accessories.

Specifications

Table - Unit Data

* For wire length over 24 ft., consult the National Electrical Code for proper sizing.

** Dometic Corporation provides GENERAL guidelines for generator requirements based on experience. Total RV power usage and generator altitude/maintenance must be considered when sizing.

*** CIRCUIT PROTECTION: Time Delay Fuse or Circuit Breaker Required.

Roof Requirements

• A 14-1/4" x 14-1/4" (±1/8") square opening (roof opening) is required, conforming to NFPA 1192.
• Roof construction must have rafters/joists supporting frames on a minimum of 16-inch centers.
• Distance between roof to ceiling must be between 1.5 and 6 inches.

Installation Instructions

Choosing Proper Location For Unit

The unit is designed for RV roof installation. Consider RV size, window area (heat gain), insulation, geographical location, and personal comfort level.

Normal Locations: Fit over an existing roof vent opening.

Other Locations: If no roof vent is available or desired:

• One Unit: Mount slightly forward of center (front-to-back) and centered side-to-side.
• Two Units: Install one unit 1/3 and one unit 2/3 from the front, centered side-to-side.

Installation on a relatively flat and level roof section is preferred. See table for maximum acceptable tilt.

Diagrams for Model Dimensions and Roof Opening:

• FIG. 1: Models 457915, 459516 dimensions and roof opening.
• FIG. 2: Models B57915, B59516 dimensions and roof opening.
• FIG. 3: Models 540315, 540316 dimensions and roof opening.
• FIG. 4: Models 640312, 640315 dimensions and roof opening.
• FIG. 5: Models 640312C, 640315C, 640316C dimensions and roof opening.
• FIG. 6: Models H540315, H540316 dimensions and roof opening.
• FIG. 7: General diagram showing unit placement relative to roof opening and airflow clearance.

After Location Selection:

• Check for obstructions in the installation area (refer to figures).
• NOTICE: Maintain structural integrity. The roof must support 130 lbs when RV is in motion (200 lb static load design is usually sufficient).
• Check inside the RV for Air Distribution Box (ADB) obstructions (e.g., door openings, dividers, curtains).

Roof Preparation

WARNING: FIRE OR ELECTRICAL SHOCK HAZARD. Ensure no obstacles (wires, pipes) are inside RV roof/floor/walls. Shut OFF gas supply, disconnect 120 Vac power, and disconnect 12 Vdc battery terminal BEFORE drilling or cutting.

Opening Requirements: Read all instructions before preparing the ceiling opening. If an existing roof vent opening is not used, a new opening must be cut between roof reinforcing members.

Roof Vent Removal: Unscrew and remove the vent, remove old caulking, and seal screw holes with weather sealant.

If the opening exceeds 14-3/8" x 14-3/8", resize it per "B. Roof Requirements". If less than 14-1/8" x 14-1/8", enlarge it.

New Opening: Mark and cut the required roof opening per "B. Roof Requirements". NOTICE: NEVER create a low spot on the RV roof to prevent water pooling. Frame the opening with at least 3/4" thick stock for support, ensuring it won't collapse when bolting. Provide an entrance hole for power supplies.

Wiring Requirements

Route a grounded 120 Vac supply wire from the breaker box to the roof opening using approved cable. If a vent fan wire was removed, it may be reusable if suitable.

• Supply wire must be in the front portion of the roof opening.
• Use an appropriately sized time delay fuse or circuit breaker (see "A. Table - Unit Data").
• Ensure at least 15" of supply wire extends into the roof opening for easy connection.
• Protect the wire where it passes into the opening.

Placing Unit On Roof

1. Remove unit from carton.

2. CAUTION: LIFTING HAZARD. Use proper lifting technique. Place unit on the roof.

3. NOTICE: Do NOT slide the unit to avoid gasket damage and leaks. Lift and place the unit over the opening, using the gasket as a guide (See FIG. 9).

4. Place the ADB kit (containing mounting hardware) inside the RV. This completes the outside work; minor adjustments can be made from inside.

Installation Preparation

1. Check and adjust unit gasket alignment over the roof opening. Unit may be moved slightly from below (See FIG. 10).

2. Remove ADB and mounting hardware from carton (See FIG. 11).

3. All models use a four (4) bolt pattern for ADB installation.

4. Pull the unit electrical cord down through the return air opening for connection (See FIG. 12).

Duct Divider Installation

1. Measure ceiling thickness (See FIG. 12).

2. Cut away rows from the duct divider based on ceiling thickness per the provided table.

3. Carefully install the duct divider in the roof opening, 5-5/8" from the back of the roof opening, with the foil side facing the rear of the unit (See FIG. 14).

Installing Unit

1. Ceiling Template Installation:

• Plug the 6-pin electrical cord from the top unit into the electronic control box connector. It is polarized and fits only one way (See FIG. 15).
• Install the non-metallic cable connector in the junction box cutout, ensuring proper orientation (See FIG. 15).
• Route the 120 Vac supply wire through the cable connector into the junction box. Secure the clamp, avoiding wire damage (See FIG. 15).
• Hold the ceiling template up to the roof opening, aligning the channel with the duct divider (See FIG. 16).
• Start each mounting bolt by hand through the ceiling template and into the unit base pan (See FIG. 17 & FIG. 18).
• NOTICE: Tighten mounting bolts evenly to 40-50 inch-pounds. Overtightening can damage the unit or template; undertightening can cause leaks.

120 Vac Power Supply Connection

WARNING: ELECTRICAL SHOCK HAZARD. Ensure 120 Vac power is disconnected from the RV. Failure to obey could result in death or serious injury.

WARNING: ELECTRICAL SHOCK HAZARD. Provide grounding per applicable electrical codes. Failure to obey could result in death or serious injury.

Connect white-to-white, black-to-black wires using appropriate connectors. Secure bare copper ground wire under the grounding screw in the junction box (See FIG. 19).

Tape connectors to the supply wire to prevent vibration. Push wires into the junction box and install the cover (See FIG. 19).

Installing ADB

1. Align the ADB with the ceiling template (See FIG. 20 & FIG. 21).

2. Install two (2) sheet metal screws inside the return air opening to secure the ADB to the ceiling template (See FIG. 22).

3. Install eight (8) wood screws into the front, rear, and side doors to secure the ADB to the ceiling (See FIG. 22).

4. Install front and rear doors.

5. Place the filter in the return air vent grille (it may be pre-installed) (See FIG. 23).

6. Install the return air vent grille into the ADB by sliding its tab into the slot and rotating it up to snap in place (See FIG. 24).

7. Install the control knobs into the ADB (See FIG. 25).

8. Unit installation is complete. Turn on the power supply.

9. Verify all system features work. Read operating instructions before running the unit.

Operating Instructions

Controls

1. The Selector Switch has 8 positions (including "OFF") for fan speeds, cooling modes, and optional heating modes (See FIG. 26).

2. The thermostat controls compressor On/Off operation between approximately 65°F and 90°F at the ADB inlet.

"OFF" Position [i]

1. Turns the unit off.

Cooling Operation (Blue Graphic)

1. Turn selector switch to cooling (blue graphic).

2. Set the thermostat to the desired temperature.

3. Select fan speed:

• HIGH COOL: For maximum cooling and dehumidification.
• MEDIUM COOL: For normal or average cooling.
• LOW COOL: For maintaining comfort, often used for nighttime operation.

[i] The compressor cycles On/Off to maintain the selected temperature. The fan runs when the compressor is off to ensure uniform temperature.

NOTICE: Wait at least 2 minutes before restarting the compressor after manual cycling to prevent quick-cycling and overload.

Heating Operation (With Electric Heater Option Installed)

[i] The heat mode is for removing chill on cool days, not for replacing a furnace in cold weather.

1. Turn selector switch to "OPT HEAT".

2. The heat strip will activate.

3. When desired temperature is reached, switch to "OFF" or "FAN" position.

[i] Thermostat does not control the fan/heater cycle.

Fan Operation (Black Graphic)

[i] Circulates air without cooling or heating. Turn selector switch to fan (black graphic) for high, medium, or low speed (See FIG. 26).

Center Air Discharge

1. Slide lever to open and close (See FIG. 27).

Maintenance

Air Filter

1. Periodically (minimum every 2 weeks), remove the return air filter behind the vent grille. Wash with soap and warm water, let dry, and reinstall.

[i] NEVER run the unit without the air filter; this can plug the evaporator coil and degrade performance.

ADB Housing

1. Clean ADB housing and control panel with a soft cloth dampened with mild detergent. Avoid furniture polish or scouring powders.

Fan Motor

1. The blower motor is factory lubricated and requires no service.

General Information

Frost Formation On Cooling Coil

Frost on a portion of the coil is normal. Ice may form under certain conditions, indicated by very cold output at low air speed. If this occurs, inspect and clean the filter, ensure air vents are open and unobstructed. Frosting is more likely at lower outside temperatures. Adjust thermostat to a warmer setting (counter-clockwise). If frosting continues, operate on FAN ONLY until the coil is frost-free, then resume normal operation. Contact service if frost persists.

Heat Gain

The unit's ability to maintain desired temperature depends on the RV's heat gain. Reduce heat gain by:

• Parking in shade.
• Using window shades (blinds/curtains).
• Keeping windows and doors closed.
• Avoiding heat-producing appliances.

High Fan/Cooling mode provides optimum efficiency in high humidity or high outside temperatures. Starting the unit early can improve its ability to maintain indoor temperature.

Condensation

The manufacturer is not responsible for damage caused by condensation. Air moisture condenses on surfaces below the dew point. The unit removes moisture during operation. Keeping doors and windows closed reduces condensation.

Air Distribution

In cool mode, at least 2 distribution vents must be open (or quick cool vent + one other) to prevent coil freezing and ensure proper function.

Service - Unit Does Not Operate

Before calling for service, check the following:

• If using a generator, ensure it is running and producing power.
• If connected to a land line, ensure the line is properly sized and connected.
• Check fuses or circuit breakers; ensure they are not blown or tripped.

If problems persist, call your local service center. Service must be performed by qualified personnel.

When calling for service, provide unit model/serial number (found on base pan, requires removing return air grille) and ADB model/serial number (found on ceiling template rating plate).

Wiring Diagrams

Wiring diagrams are provided for unit models (457915, 459516, B57915, B59516; 540315, 540316, H540315, H540316; 640312, 640315, 640316) and the ADB.

Diagrams include:

• Unit Wiring Diagrams (A)
• ADB Wiring Diagram (B)