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