How to spec the right rooftop A/C unit to make... it delivers the performance customers expect.
How to spec the right rooftop A/C unit to make sure it delivers the performance customers expect. When it comes to operator comfort, two key selling points for any vehicle are space and visibility. But big interiors and lots of window glass add to the demands placed on another critical comfort item: the air conditioner. “As a trend, we’re seeing more spacious cabs and larger windows in every type of vehicle we design for,” says Gary Hansen, vice president of engineering at Red Dot Corporation, a leader in heavy-duty mobile HVAC units and replacement parts. Replacement Parts & Service: Align your Preventative Maintenance (PM) schedules Scheduled preventive maintenance is the best way to make sure an A/C system is effective and efficient. Start by synchronising your HVAC parts replacement with engine lube intervals. The accompanying chart shows you how. “Most HVAC PM intervals involve a three-month, six-month or annual inspection,” says Hansen. “When a vehicle is in for scheduled service, follow the recommended inspection schedule for the compressor and belt-drive system, condenser, receiver-drier, expansion valve and evaporator.” “A rooftop A/C unit is ideal for bigger cabs because it can deliver high-performance cooling without taking up valuable interior space.” Because it’s mounted on the cab’s exterior, a rooftop A/C unit should be purpose-built to handle impact, vibration, and other demanding operating conditions, Hansen says. He offers these tips below to help you make the right choice. Cool, clean, reliable air is vital to operator safety as well as comfort. Promote regular preventive maintenance and quality all-makes parts and you’ll generate HVAC parts and service business all year long. It’s A/C season all year The best way to cut down on A/C-related repair costs is to incorporate inspections into your overall PM routine. Here’s where to start: R-6100: Low-profile, high-performance applications Maintenance Interval (Months) Why it’s different: The R-6100 extends just 7.4 inches above the roofline so it won’t interfere with bodies or other equipment that may protrude over the cab. Beneath the sleek, roto-molded housing is a tightly integrated package of components designed for long life and efficiency. For example: • Tube-and-fin coil construction ensures strong condenser performance in dusty, dirty conditions. The copper tubing is 0.022 inches thick, resulting in an effective, lightweight, rugged coil. • The sealed motor is a permanent magnet type with a slinger ring and hubcap for weather protection. The condenser unit’s fan is aluminum with a heavy-duty spider and riveted blades. For example, Red Dot use a sealed, long-life evaporator and condenser motor with a slinger ring and hubcap for protection from weather and dust. Instead of using several small hinges for the service panel, the R-9727 has one continuous stainless 12 Perform manifold gauge check. If gauge pressures indicate low refrigerant charge: 1) Recover and recycle refrigerant; 2) Perform system evacuation and leak test; 3) Recharge system • Once a month, engage the A/C and run the system for 5 minutes to lubricate the compressor and verify that the condenser (engine) fan engages and disengages • A high-capacity, spring-loaded receiver drier helps stop moisture from compromising the performance and life of the system. Check discharge line (warm or hot to touch) • Check suction line (cool to touch) • Inspect face of clutch hub for signs of slippage (heat discoloration) • Check clutch working voltage and current draw • Inspect shaft seal for oil or dirt (indicates leakage) • Applications: Heavy and medium-duty trucks and other onhighway equipment cabs that require a low-profile rooftop unit. Confirm clutch pulley alignment with crankshaft drive pulley • Ordering information: See page 473. Inspect compressor belt for glazing or cracking • Check belt tension • It also saves space inside. The R-6100 ceiling plenum houses the controls for the blower and thermostat as well as a cab air filter yet protrudes barely 1.5 inches below the headliner. Inspect idler pulley for bearing wear (looseness) • 3. Condenser No rooftop mobile A/C unit has a more proven track record than the Red Dot R-9727. It delivers 22,000 BTU/hour of cooling and airflows of 320 CFM (evaporator) and 850 CFM (condenser), and its durability and performance are best-in-class for rugged on and off-road environments. The R-9727’s robust components are housed in a heavygauge steel casing that’s gusseted and reinforced to increase its structural integrity. “Little things add up to a more durable, reliable unit,” Hansen says. 6 2. Compressor & Belt Drive System R-9727: Robust and rugged rooftop A/C Why it’s different: Some units may look like the R-9727 but only the real thing will deliver the performance and durability equipment owners expect. 3 1. Annual System Maintenance Red Dot’s R-6100 is the ideal low-profile rooftop A/C unit for commercial trucks and other on-highway equipment. It produces a strong, steady stream of cool air—16,000 BTU/hour and airflow of 265 CFM. At that rate, the operator can work with the door open and still feel the effects of spot cooling. Clean dirt and bugs from condenser fin area (more frequently if necessary) • Inspect fins and straighten as necessary • Inspect tubes for dents and stains (indicating leakage) • 4. Receiver Drier Replace annually or after the system has been opened steel piano hinge. The result is a stronger joint that contributes to the rigidity of the housing while ensuring accessibility to the components when service is necessary. • Check inlet line from condenser (warm to touch) • Check temperature of drier canister (warm to touch) • New for 2011: Red Dot will offer a hydraulic compressor upgrade kit for the R-9727 that attaches to the back of the unit, the perfect solution when you can’t run the compressor directly from the engine. 5. Expansion Valve Applications: Mining, agriculture, construction. 6. Evaporator Ordering information: See page 474. • Check sight glass for signs of moisture or bubbles Check inlet (liquid) line from drier (warm to touch) • Inspect refrigerant charge head for damage and leakage • Clean dirt and bugs from evaporator fin area (more frequently if necessary) • Check temperature of copper inlet plumbing tube behind expansion valve (same temperature as outlet tube) • 7. Other Components R-9976 Hydraulic Compressor: Flexibility for tough installations Thermostat: Check for proper operation Red Dot’s R-9976 hydraulic compressor gives you flexibility on applications where an engine-mounted compressor isn’t the best option for a rooftop A/C unit. Air filters: Check for restriction; clean or replace as required • • Pressure switches: With manifold gauges installed, check for proper operation • Water valve: With control panel temperature setting on full "cold," check valve for full closure and adjust cable as needed The R-9976 direct-drive hydraulic compressor requires no belts or clutch and minimizes A/C hose length - ideal for cranes and articulated equipment where the cab and engine are far apart. Available in displacements of 5 and 9.3 cubic inches. • Credit: Red Dot Corp. Ordering information: See page 68, 93, 476. 470 Contents Index Contents 471 Index Rooftops Rooftops R9757 SERIES R6100 SERIES R97570P R61000P Red Dot Rooftop Air Conditioner / Heater 12V • Height: 292mm • Width: 657mm • Length: 857mm • Weight: 61kg • BTU’s: 25000 cooling • BTU’s: 45000 heating Red Dot Rooftop Evaporator Assembly 12V • Height: 188mm • Width: 642mm • Length: 790mm • Weight: 20kg • BTU’s: 16000 cooling R6100024P R9757024P Red Dot Rooftop Evaporator Assembly 24V Red Dot Rooftop Air Conditioner / Heater 24V 857mm 857mm 642mm 657mm 790mm 292mm 188mm 326mm Part No. Description Red Dot Ref. No. RD550491P Motor Dual Shaft 12V 73R4422 RD550492P Motor Dual Shaft 24V 73R4424 RD580920P Evaporator Blower Wheel CW RD580921P Evaporator Blower Wheel CCW RD447240P Condenser RD587474P Condenser Fan Assembly 12V 13” RD587475P Condenser Fan Assembly 24V 13” RD587901P Fan Guard Assembly RD227910P 472 Evaporator Coil Page No. Red Dot Ref. No. Part No. Description 14 RD568330P High Pressure Switch 71R7075 17 RD536470P Resistor 71R1450 73R7200 22 RD5453124P Thermostat 71R3200 73R7210 22 RD566900P Relay 12V 71R1902 77R0660 185 RD566930P Relay 24V 71R1904 73R8652 262 RD569172P Control Cable Water Valve RD559280P Control Knob RD563951P Low Pressure Switch 71R6040 RD364010P Plenum Plastic Assembly RD41232P Mode Switch ON - OFF - ON RD500710P RD538460P 73R8654 Page No. Red Dot Ref. No. Part No. Description 393 RD211890P Cover Assembly Outer 482 RD572970P Fan Blade 73R8100 582 RD571290P Motor 12V 73R0542 483 RD5712924P Motor 24V 73R0544 483 RD572720P Receiver Drier 74R2546 72R9005 N/A RD545830P Pressure Switch Trinary 71R4040 483 RD447380P Condenser Coil 393 RD211950P Evaporator Coil 477 RD568680P Block TX Valve 71R0200 481 RD566900P Relay 12V Fan Switch ON - OFF - ON 71R0400 482 RD566930P Louvre Assembly 4.5” 72R3200 368 RD412536P 257mm Page No. Red Dot Ref. No. Page No. Part No. Description 477 RD573120P Blower Wheel CCW 73R6300 22 268 RD551211P Motor Dual Shaft 12V 73R4262 14 7 RD5512124P Motor Dual Shaft 24V 73R4254 117 12 RD573110P Blower Wheel CW 73R6350 22 448 RD536470P Resistor 71R1450 482 71R7550 392 RD209610P Roof Seal 477 77R0620 N/A RD212970P Plenum Gasket 477 76R5500 243 RD538460P Louvre Assembly 4.5” 72R3120 368 71R8301 495 RD559280P Knob 71R4040 683 71R1902 483 RD536460P Switch 3 Speed Rotary 71R1150 Relay 24V 71R1904 483 RD212900P Plenum Diffuser Assembly Thermostat 71R2250 522 RD559370P Recirculating Filter 262 N/A 76R6015 242 RD113790P Heater Coil 76R1860 334 RD568680P Block TX Valve 71R8301 495 RD572720P Receiver Drier 74R2546 448 RD577601P Water Valve Assembly 72R5220 N/A Contents Index Contents Index 481 477 78R5300 222 473 Rooftops Rooftops R9727 SERIES R9777 SERIES R97271P R97770P Red Dot Rooftop Evaporator Assembly 12V • Height: 264mm • Width: 624mm • Length: 768mm • Weight: 47kg • BTU’s: 22000 cooling Red Dot Rooftop Heater / Evaporator Assembly 12V • Height: 200mm • Width: 760mm • Length: 940mm • Weight: 30kg • BTU’s: 25000 cooling • BTU’s: 45000 heating R9727124P R9777024P Red Dot Rooftop Evaporator Assembly 24V Red Dot Rooftop Heater / Evaporator Assembly 24V 940mm 768mm 624mm 940mm 200mm 760mm 264mm 320mm Red Dot Ref. No. Part No. Description RD435860P Condenser 77R0350 RD211212P Evaporator Coil 76R7100 RD536470P Resistor 71R1450 RD568680P Block TX Valve 71R8301 RD570611P Receiver Drier RD546400P Pressure Switch Binary RD571290P Motor 12V RD5712924P Motor 24V RD435080P 257mm Page No. Red Dot Ref. No. Description 185 RD310638P Blower Wheel Evaporator CW 73R6101 243 RD310639P Blower Wheel Evaporator CCW 73R6151 482 RD412536P Thermostat 71R2250 495 RD536460P Switch 3 Speed Rotary 71R1150 74R2536 447 RD559280P Knob 71R4040 71R7000 392 RD209610P Roof Seal 73R0542 7 RD212900P Plenum Diffuser Assembly 73R0544 12 RD538460P Louvre Assembly 4.5” 72R3120 368 Fan Blade Condenser 73R8110 268 RD559370P Recirculating Filter 78R5300 222 RD5375712P Motor Dual Shaft 12V 73R4202 14 RD538605P Complete Blower Evaporator Assembly RD5375724P Motor Dual Shaft 24V 73R4254 17 474 Contents RD539050P SPX044 Filter Assembly To suit R9727, R9757, R9800, R9777, Universal Applications • Ref. No. 78R5000 • Diameter: 260mm • Length: 457mm • Complete with all fittings to mount directly to rear of unit 3” Pre-cleaner To suit RD539050P RD542960P RD542961P SPX012 In-line Booster Pressuriser • Ref. No. 73R9202 • 12V • Inlet: 100mm • Outlet: 75mm • Weight: 3kg In-line Booster Pressuriser • Ref No. 73R9202 • 24V Flexible Air Tube • 73mm x 10m RD564271P RD554320P Rubber Elbow • Ref. No. 78R5500 • Inner diameter: 75mm Replacement Filter Element • Ref. No. 78R5210 To suit Hydraulic Axial Direct Drive • The perfect solution when you can’t run the compressor directly from the engine • GPM: 1.1 - 6.3 • Displacement: 9.3 cu.in. RD5109720P RD5124830P RD5112090P RD5112100P Drive Coupler Neoprene Spider Electronically Piloted Hydraulic Control Valve • Ref. No. 72R9904 • 24V • Normally open Converts RD5112090P from 24V to 12V • Ref. No. 72R9912 Contents Index Part No. Description Red Dot Ref. No. 186 RD585831P Blower Motor Assembly 24V 73R5554 3 243 RD566900P Relay 12V 71R1902 483 2 RD566930P Relay 24V 71R1904 483 522 RD598330P Switch Rotary 3 Speed 71R1160 481 RD589670P Switch Rocker 71R0840 482 RD590770P Recirculating Filter 78R5410 222 RD594370P Resistor 12V 71R1402 482 RD594450P Resistor 24V 71R1401 482 22 RD453780P Condenser 77R1290 23 RD234130P Evaporator Coil 76R5820 522 RD585830P Blower Motor Assembly 12V 73R5552 481 RD5453124P Thermostat Side & Bottom Mount 71R3200 RD595130P Block TX Valve 71R8380 495 RD545830P Pressure Switch Trinary 71R7550 392 RD572720P Receiver Drier 74R2546 448 RD592241P Water Valve Cable Operated 72R5285 338 RD590763P Condenser Fan Assembly 24V 73R8644 262 483 Page No. N/A Contents R99761P Page No. Description 477 Index Red Dot Ref. No. Part No. 477 Rooftops 476 Page No. Part No. Index 475
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