Vmac UNDERHOOD 40 Series User manual

www.vmacair.com
www.vmacair.com
UNDERHOOD 40Truck and Van
Series Owner’s Manual

VMAC - Vehicle Mounted Air Compressors
VMAC Technical Support: 888-241-2289
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1
Table of Contents
General Information ...........................................................3
Safety .........................................................................4
Safety Precautions.............................................................5
Warranty ......................................................................8
System Specifications.........................................................10
Identifying Your System....................................................... 11
System Components.......................................................... 12
Operating Principles .......................................................... 17
System Operation ............................................................ 19
General Maintenance Information.............................................22
Maintenance and Repair Safety ...............................................23
Regular Inspection Instructions ...............................................26
200 Hour / 6 Month Service .................................................. 31
400 Hour / 1 year Service ................................................... 34
Diagnostics and Trouble Shooting.............................................37
Adjusting the Pressure Switch ............................................... 43
Performance Testing and System Adjustments (Analog Throttle Control) ..... 44
Performance Testing and System Adjustments (Digital Throttle Control) ...... 46
Air Receiver Tank .............................................................49
Recommended Accessories .................................................. 50
Accessory Products from VMAC ..............................................51
Warranty Registration ....................................................... 56

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Document: 1930335
Changes and Revisions
Revision Revision Details Revised by
Checked by
Implemented
Eng. Tech. Qual.
Mech. Elec.
AInitial Release MSP KRM AJH GB AWG 21 Feb 2018
B ECN: 20-024 Add digital throttle MSP N/A ASE MSP LPH 22 Jan 2020
Notice
Copyright © 2020 VMAC Global Technology Inc. All Rights Reserved. These
materials are provided by VMAC for informational purposes only, without
representation or warranty of any kind, and VMAC shall not be liable for errors
or omissions with respect to the materials. The only warranties for VMAC
products and services are those set forth in the express warranty statements
accompanying such products and services, if any, and nothing herein shall be
construed as constituting an additional warranty. Printing or copying of any page
in this document in whole or in part is only permitted for personal use. All other
use, copying or reproduction in both print and electronic form of any part of this
document without the written consent of VMAC is prohibited. The information
contained herein may be changed without prior notice.
Printed in Canada
Registered Trademarks
All trademarks mentioned in this manual are the property of their respective
owners. VMAC’s use of manufacturers’ trademarks in this manual is for
identification of the products only and does not imply any affiliation to, or
endorsement of said companies.
Important Notice
The information contained in this manual is based on sound engineering principles,
research, extensive field experience and technical information. Information
is constantly changing with the addition of new models, assemblies, service
techniques and running OEM changes. If a discrepancy is found in this manual,
contact VMAC prior to initiating or proceeding with installation, service, repair or
operation. Current information may clarify the issue. Any person with knowledge of
such discrepancies, who proceeds to perform service and repair assumes all risks.
Only proven service procedures are recommended. Anyone who departs from the
specific instructions provided in this manual must first assure that their safety and
that of others is not being compromised and that there will be no adverse effects
on the operational safety or performance of the equipment.
VMAC will not be held responsible for any liability, consequential damages, injuries,
loss or damage to individuals or to equipment as a result of the failure of any
person to properly adhere to standard safety practices or the procedures set
out in this manual. Safety should be the first consideration when operating, or
performing any service to the equipment. If there are any questions concerning the
procedures in this manual, or more information is required, please contact VMAC
before beginning repairs.

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Introduction
This manual provides operating instructions, specifications, adjustment,
maintenance and warranty information for the VMAC UNDERHOOD 40 Truck
and Van Series Air Compressor systems. Read this manual prior to servicing or
operating the compressor system.
Follow all safety precautions when servicing or operating the VMAC system as
moving drive belts, fan blades and other rotating components pose an extreme
hazard.
Proper service and repair are important to the safety of the operator and the safe,
reliable operation of the equipment. Always use genuine VMAC replacement parts.
The procedures described in this manual are the only approved methods of service
and operation.
Optional Equipment Compatibility
While VMAC strives to design systems compatible with optional OEM equipment
(such as running boards), it is impractical to develop systems that accommodate
every OEM and aftermarket option or add-on. Whenever possible, VMAC
endeavors to advise of compatibility issues in the “Additional Application
Information” section of the specific installation manual. Even when specific
optional equipment is determined by VMAC to be incompatible, it does not
preclude the vehicle upfitter or end user from modifying the optional equipment to
make it compatible with the installed VMAC system. VMAC does not warranty or
accept responsibility or liability for the fitment, function or safety of any products
modified in any way not expressly outlined in the installation manual.
Ordering Parts
To order parts, contact a VMAC dealer. The dealer will ask for the VMAC System ID
(see page 11), part number, description and quantity. Locate the nearest dealer
online at www.vmacair.com/dealer-locator or call 1-877-912-6605.
General Information
Additional Support
Additional resources such as installation manuals, illustrated parts lists, the VMAC
Knowledge Base, air tool consumption guides, etc. are available at
https://www.vmacair.com/support/.

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Safety Messages
This manual contains various warnings, cautions and notices that must be
observed to reduce the risk of personal injury during operation or service, and
the possibility that improper operation or service may damage the equipment or
render it unsafe.
This symbol is used to call attention to instructions concerning
personal safety. Watch for this symbol; it points out important
safety precautions, it means, “Attention, become alert! Your
personal safety is involved”. Read the message that follows and
be aware of the possibility of personal injury or death. As it is
impossible to warn of every conceivable hazard, common sense and
industry standard safety practices must be observed.
This symbol is used to call attention to instructions on a specific
procedure that if not followed may damage or reduce the useful life
of the compressor or other equipment.
This symbol is used to call attention to additional instructions or
special emphasis on a specific procedure.
Safety

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Harmful Vapours
Breathing fuel vapours or engine exhaust can expose you to chemicals
known to the State of California to cause cancer and birth defects or
other reproductive harm.
• Always start and operate the engine in a well ventilated area.
• Do not breathe engine exhaust, internal combustion engines
produce carbon monoxide, a poisonous odorless gas which can
cause death. Do not start or operate this compressor in an
enclosed area.
• If in an enclosed area, vent the exhaust to the outside and ensure
there is adequate access to fresh breathable air..
Burn Hazard
• The compressor system gets very hot during operation, contact
with the components or the oil can cause serious injury. Allow
sufficient time for the system to cool before performing service.
• Never allow any part of your body to contact the engine or
compressor components.
• Do not attempt to service the compressor until it has sufficiently
cooled.
As the VMAC compressor system is an industrial grade compressor,
it is assumed that the operator has been trained in industry specific
safety practices.
Read this information before operating the compressor for the first time. Follow
the information and procedures in this manual for operation, maintenance and
repair.
Follow all safety precautions for safe operation or service. Moving belts and
rotating components are an extreme hazard. Stay clear of all moving parts when
the system is operating. Only qualified personnel should perform maintenance and
repair on system components and only while the system is properly shut down and
depressurized.
Proper service and operation are important to the safety of the operator and the
safe, reliable operation of the equipment. Always use genuine VMAC replacement
parts.
The procedures described in this manual are effective methods of service and
repair. Some procedures may require the use of special tools designed for a
specific purpose. Anyone using a replacement part, service procedure or tool must
ensure that neither their safety, nor the safe operation of the equipment will be
compromised by the replacement part, service procedure or tool selected.
Safety Precautions

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Personal Safety
• Follow all safe work practices.
• Do not breathe the compressor air. Vaporized oil is a respiratory
hazard.
• Service should only be performed by qualified personnel.
• Always use the appropriate personal protective equipment,
particularly eye and hearing protection when operating or servicing
air powered equipment.
• Do not leave the vehicle unattended.
Fire and Explosion Hazard
• Vaporized oil propelled by high pressure air is a potentially
explosive mixture.
• Fire in the compressor can cause an explosion and flame projection.
Should this occur, there is potential for serious injury or death.
• Operate the compressor system in a well ventilated area free of
flammable vapors, dust, or other combustible materials.
• Never place objects against or near the compressor components.
• Never expose the WHASP Tank or compressor to extreme heat.
• Serious injury or death may result from an air tank explosion.
• Never exceed manufacturer’s maximum air pressure rating.
• Do not repair components, only replace with approved parts.
• Do not tamper with or disable factory safety equipment.
Compressor Air and Oil Hazard
• The compressor system is under sufficient pressure that a leak
could force the air/oil mixture through the skin directly into the
bloodstream. This could cause serious injury or death.
• Ensure the system is completely depressurized before attempting
maintenance or repair.
• Do not use compressed air to clean off clothing or skin, compressed
air can penetrate the skin causing serious injury or death.
• Do not service the compressor while it is pressurized or operating.
• Components and hoses under pressure could separate suddenly,
causing serious injury or death. If equipped, the air receiver
tank must be drained before servicing any components in the
compressor system.
• Never adjust or attempt to make any repairs to the system while
the engine is running.

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Moving Parts Hazard
• Before performing service, disconnect the negative battery cable.
• Avoid contact with drive belts and other moving parts while the
system is in operation.
General Warnings
• Be attentive for unexplained changes in operation and record any
changes.
• Check the compressor oil level and condition before starting the
system. Do not add or change oil while the system is running. Use
only approved oil.
• The compressor operates anytime the engine is running.
• Keep hoses and wiring away from hot, sharp, or moving
components.
• Use only approved hoses and replacement parts.
• Do not modify the equipment.
• Do not operate the air compressor when fatigued or under the
influence of alcohol or drugs.
• Know how to operate the compressor, read this manual prior to
operation.
• Inspect equipment before every use.
• Never bypass or disable any of the safety equipment.
• Never adjust or attempt to make any repairs to the compressor
system while the engine is running or the air system pressurized.
Components and hoses under pressure could fail and cause serious
injury or death.

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VMAC Standard Warranty (Limited)
For complete warranty information, including both VMAC Standard
Warranty (Limited) and VMAC Lifetime Warranty (Limited)
requirements, please refer to our current published warranty located
at: www.vmacair.com/warranty
If you do not have access to a computer, please contact us and we
will be happy to send you our warranty.
VMAC’s warranty is subject to change without notice.
VMAC Lifetime Warranty (Limited)
A VMAC Lifetime Limited Warranty is offered
on the base air compressor only and only on
UNDERHOOD, Hydraulic Driven, Transmission
Mounted, Gas and Diesel Engine Driven Air
Compressors, Multifunction Power Systems, and
other products as defined by VMAC, provided that
(i) the purchaser fully completes and submits a
warranty registration form within 3 months of purchase, or 200 hours of operation,
whichever occurs first; (ii) services are completed in accordance with the Owner’s
Manual; (iii) proof of purchase of applicable service kits are made available to
VMAC upon request.
The VMAC Lifetime Warranty is applicable to new products shipped on or after
1 October, 2015.
Warranty Registration
The VMAC warranty registration form is located near the back of this manual. This
warranty registration form must be completed and sent to VMAC at the time of
installation for any subsequent warranty claim to be considered valid.
There are 4 ways the warranty can be registered with VMAC:
www.vmacair.com/warranty
[e-mail]
[phone]
VMAC - Vehicle Mounted Air Compressors
1333 Kipp Road, Nanaimo, BC, Canada V9X 1R3
LIFETIME
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WARRANTY
Warranty

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VMAC warranty work must be pre-authorized by VMAC. Claims are
processed via our dealer network. If you are not a VMAC dealer,
please select one to work with via our Dealer Locator:
https://www.vmacair.com/dealer-locator/
1. Communicate with VMAC Technical Support at 1-888-241-2289 or
[e-mail] to help diagnose/troubleshoot the problem prior to repair.
VMAC technical support will require the VMAC System ID, hours on the
compressor and mileage on the vehicle.
2. VMAC will provide direction for repair or replacement of the failed components.
3. If requested, failed parts must be returned to VMAC for evaluation.
4. Dealers may login to the VMAC website to view the "VMAC Labour Time Guide"
(under “Agreements”) to see the allowable warranty labour times.
5. Warranty invoices must include the Service Ticket number, VMAC System ID#,
hours on the compressor, and a detailed description of the work performed.
6. VMAC Warranty does not cover consequential damages, overtime charges,
mileage, travel time, towing/recovery, cleaning or shop supplies.
7. Dealers submit warranty claims on behalf of the Vehicle Owner/End User
affected by the defective part(s). The dealer ensures that all warranty credits
are refunded back to the Vehicle Owner/End User who made the initial warranty
claim.
In order to qualify for Lifetime Warranty (Limited), the completed
warranty registration form must be received by VMAC within 3
months of the buyer receiving the Product(s), or 200 hours of
operation, whichever occurs first.
If the completed warranty registration form has not been received
by VMAC within 3 months of the buyer receiving the Product(s),
or 200 hours of operation, the warranty period will be deemed to
commence 30 days from the date of shipment from VMAC.
Failure to follow the warranty claim process may result in denial of
the warranty claim.
VMAC Product Warranty Policies & Warranty Registration can be found on the
VMAC website (see previous page for URL).
VMAC Warranty Claim Process

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Model
• UNDERHOOD 40 Truck/Van Series Air Compressor.
Compressor Type
• Flooded lobe, rotary screw.
Drive System
• Front End Accessory Drive (FEAD).
Control
• Electric on/off 12 V clutch control.
Maximum Air Delivery
• Up to 40 cfm @ 150 psi (dependent upon vehicle installation and engine speed).
Pressure Regulation
• Mechanical pressure switch on the air/oil separation tank signals the
compressor clutch to engage/disengage in response to air demand.
Engine Control
• Single speed throttle control (Maximum rpm adjustable by the end user).
• Elevated engine speed in response to air demand.
Safety Features
• 200 psi (1380 kPa) pressure relief valve in the Waste Heat Air Oil Separation
Package (WHASP) Tank.
• Thermal monitoring and electronic control.
• Rapid blowdown valve to relieve system pressure on shutdown.
System Specifications
Use only genuine VMAC replacement parts to maintain the system.
Genuine VMAC replacement parts are designed to work with the
high pressure and heat generated by the compressor. Substituting
genuine VMAC replacement parts may void the warranty and could
cause equipment damage, injury, or death.
Lubrication
• VMAC High Performance Compressor Oil.
Filters
• Air filter: Replaceable paper element.
• Oil filter: High pressure spin-on.
• Coalescing filter: High pressure spin-on.

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Identifying Your System
The System ID will be requested any time that parts are ordered, when calling for
technical support or submitting a warranty claim.
The system ID is the preferred method of identifying the system as it serves as
a master record of all of the components in the system. The system ID plate is
generally found on the radiator cross member, or in some instances, the inner
fender or firewall (Figure 1).
An alternative method of identifying the system is via the compressor serial
number which is found on a plate attached to the compressor. This is a less
desirable method of identifying the system as it may not link back to the original
system if it has been replaced.
System ID breakdown
The system ID provides specific information about the system such as the model,
revision, production date and the unique identifier (Figure 2).
Figure 1 — System ID location
Figure 2 — System ID breakdown
Model number
Revision letter Production date code
Unique identifier
V400001 A BC 123

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System Components
The UNDERHOOD 40 Air Compressor system consists of the following components:
• Waste Heat Air Separation Package
(WHASP) Tank.
• Compressor.
• Oil return, Air/Oil discharge hoses.
• PTFE oil scavenge tube.
• Control module.
• Interface panel.
• Throttle control.
WHASP Tank
Coalescing
filter
Pressure
relief valve
Air outlet
Blowdown
muffler
Minimum
pressure
check valve
Oil filter
Oil return
fitting
Air/oil
inlet
Fan
Oil scavenge fitting
(includes check valve)
Oil fill cap
Oil drain
Oil sight glass
Pressure
switch
Figure 3 — WHASP Tank

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Compressor
Hoses / Tubes
Figure 4 — Compressor
(Top inlet version)
Temperature probe
and harness
Air intake
Oil return
Air/oil
discharge
Oil scavenge
Clutch
The hoses used in VMAC compressor systems have an AQP inner liner that is
compatible with VMAC compressor oil. The PTFE tube used in VMAC systems is
rated for the high temperatures VMAC compressors generate. Use of hoses or
tubes other than those supplied or recommended by VMAC may cause compressor
damage and may void your warranty. Please contact VMAC for replacement
hoses/tubes or for further information.
• Hoses must have an AQP liner.
• Oil scavenge tubes must be PTFE.
VMAC Compressor oil will degrade rubber lined hoses, use only
hoses with an AQP elastomer type liner. Contact VMAC Technical
Support at 1-888-241-2289 for further information.
Air filter

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Figure 5 — Control module
Interface Panel
The interface panel serves as the operator’s control panel and contains the
“ON/OFF” switch, compressor status light, and the compressor hour meter.
Control Module
The control module serves as the primary input/output interface between the
vehicle and the various VMAC components (compressor, throttle control, WHASP
Tank, Control Interface, etc.).
Figure 6 — Interface panel
“ON/OFF”
switch
Compressor
hour meter
Compressor
status light
Control
module plug
Power, 12 V
(switched), and
WHASP fan
Clutch, throttle
control, and
Interface panel
WHASP
pressure
switch
Compressor
temperature
sensor

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VMAC Analog Throttle Control
Ford Stationary Elevated Idle Control (SEIC) Compatible Throttle Control
Figure 7 — VMAC digital throttle control
“SPEED1”
adjusting screw
(under side)
Engine speed
adjusting
knob
Figure 8 — Analog VMAC throttle
Figure 9 — VMAC throttle control for Ford SIEC systems control
Throttle Control (Figure 7, Figure 8, Figure 9)
The throttle control responds to signals from the control module and commands the
vehicle’s throttle to increase or decrease engine speed in response to air demand.
The throttle control also allows the operator to configure the vehicle’s engine speed
(when air is demanded) to their needs (maximum cfm, specific tool requirements,
fuel efficiency, or a combination of these factors).
VMAC Digital Throttle Control
Not used
OBDII
Accelerator
pedal Not used
Control module,
transmission, park
brake, ground

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Component Placement Overview
Van Layout
Figure 10 — General component overview
(Actual installation locations may vary)
Compressor
Interface
panel
Control
module
Throttle
control
WHASP
Tank
Pickup layout
Interface
panel
Control
module
Throttle
control
WHASP
Tank
Figure 11 — General component overview
(Actual installation locations may vary)
Compressor

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Operating Principles
Air Compression
At the heart of VMAC’s UNDERHOOD 40 Air Compressor systems is a flooded
lobe, rotary screw compressor.
Compression occurs when filtered air, at normal atmospheric pressure, enters the
chamber where it is trapped between meshing rotor lobes. Cooled oil is injected
into the compressor housing during compression to seal the rotor lobes for
maximum compression efficiency. The oil also lubricates the rotors and bearings
and absorbs some of the heat generated during compression. As the rotors rotate,
the meshing lobes compress the volume of air before sending the air/oil mixture
down the discharge hose to be separated and cooled by the WHASP Tank.
Oil Separation and Cooling
The system uses a proprietary 2 stage air/oil separator and cooler called a WHASP
Tank. The hot air/oil mixture from the compressor enters the cooler on top of the
tank where the mixture is cooled and the majority of the oil separates from the
air and settles into the tank below the cooler (this is the first separation stage).
The cooled oil passes through a high pressure oil filter and is returned to the
compressor via the oil return hose.
The cooled air (with any remaining oil) then passes through a coalescing filter
which removes the last of the oil from the air stream. Oil from the coalescing filter
is returned to the compressor via the 1/4 in PTFE scavenge tube.
The WHASP Tank is manufactured with an integrated minimum pressure check
valve (MPCV) to ensure a minimum of 60 psi (415 kPa) is maintained in the tank to
ensure proper oil flow while the clutch is engaged and the system is compressing
air. Air will not flow out of the WHASP Tank until this pressure is reached. The
MPCV is factory set and does not require service or adjustment.
The VMAC WHASP Tank has a built-in check valve. Use of an
additional check valve is not required and may cause erratic
performance.
Filtration
VMAC rotary screw compressors are designed and machined to exacting
standards. Foreign particles entering the compressor can damage components
such as rotors, bearings, seals, and the housing resulting in performance and
efficiency loss and reduced system life.
The system is equipped with a replaceable paper element air filter as well as high
pressure spin-on oil and coalescing filters.
Belt Alignment and Tensioning
Dependent upon the application, the UNDERHOOD 40 Air Compressor system
may be driven by either the OEM FEAD belt, or a dedicated FEAD belt. On systems
driven by the OEM FEAD belt, the compressor typically mounts in the secondary

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alternator location. While the OEM FEAD belt may be replaced with a longer one (if
required), the OEM belt tensioning system will remain the same and the OEM belt
servicing interval should be followed.
Systems using a dedicated FEAD belt are equipped with an automatic tensioner
and do not require manual adjustment.
Dependant upon the specific system, the compressor may be driven by a FEAD
belt with up to 8 ribs. To ensure proper belt alignment, verify the belt is centered
on the clutch (e.g. a 4 rib FEAD belt will sit on the middle 4 grooves of the
compressor clutch with 2 grooves showing on either side of the belt).
Pressure Regulation and Engine Speed Control
When shut down, the VMAC system “blows down” or discharges all air stored in the
WHASP Tank. When the system is started, the mechanical pressure switch in the
WHASP Tank senses a lack of pressure and sends a signal to the control module
to simultaneously engage the compressor clutch and signal the throttle control
to increase engine speed. Once the system has built to full system pressure (150
psi/1030 kPa), the pressure switch signals the clutch to disengage and the throttle
control to reduce engine speed to base idle. The mechanical pressure switch detects
air use and will send a signal to engage the clutch and increase engine speed once a
40 psi drop in pressure is detected.
The VMAC control system offers the following benefits:
• Reduced fuel consumption when not using air.
• Reduced load on the compressor cooling system.
• Reduced noise when not using air.
• Quick response to airflow demands.
The elevated engine speed and “cut-out” (maximum) pressure on the pressure
switch are adjustable (“cut-in” pressure moves in conjunction with “cut-out”
pressure). Higher engine speeds will yield higher compressor output (cfm) but will
generate more noise and consume more fuel.
Safety Features
A 200 psi pressure relief valve is installed in the WHASP Tank to prevent over
pressurization. The WHASP Tank is also equipped with an integrated rapid blow
down system that automatically discharges pressure from the WHASP Tank upon
shutdown.
The UNDERHOOD 40 Air Compressor control logic utilizes built in safety circuits,
in addition to OEM safety controls (if present), to prevent increasing engine rpm
when certain conditions are not met. This helps to protect both the operator/
occupants and the vehicle should the VMAC system be inadvertently activated at
an inappropriate time.
In the event that the air/oil temperature increases above a safe temperature, the
temperature sensor in the compressor will signal the control module which will
disengage the clutch and signal the throttle control to return the engine speed to
base idle. The control module will also display the error code via the compressor
status light on the interface panel.