Fleet Maintenance - 35

is run. Dennehy and Stencil recommend that cab
heaters or the engine coolant preheaters are run a
minimum of 15 minutes at least once per month.
"This helps keep the fuel system primed,
promotes cleaning of the inside of the heater
combustion chamber, and most importantly, the
heater works when you need it," they say.
Though Dennehy and Stencil acknowledge
that running the heater won't help if an issue
already exists, running the system regularly will
likely alert fleets of any issues, meaning maintenance can be performed before a complete
system failure.
In addition to checking the heater, the A/C
should also be tested.
"Some people are not aware of this, but when
you turn on your defrost in the winter time,
the A/C system also comes on to provide you a
dry, warm air coming out of the defrost vents,"
Dennehy and Stencil say. "This also helps the A/C
system stay working because ... it helps exercise
the components of the A/C system."
A properly functioning HVAC system is important for driver and passenger comfort and safety.
The HVAC system helps to prevent moisture buildup on the truck's windows, as well as defrost them,
so the driver's visibility is not impaired, explains
Tim Wagaman, senior product manager at Bosch
Automotive Service Solutions, a provider of diagnostic and repair shop equipment.
Wagaman also notes that a well-run HVAC
system will help keep other systems within the
truck running smoothly in cold weather.

Common HVAC issues

As fleets prep for the cold winter months, there
are a variety of HVAC issues to keep an eye out for
such as proper air flow, A/C leaks, the accumulator/dryer becoming super-absorbed, and lost fuel
prime. Most issues within the HVAC system can
be avoided with preventive maintenance.
Air flow
"One of the first things to check should be your
blend door, which is essentially a 'door' that opens
and closes to direct which passages the warm or
cool air flows through," Wagaman says. "Cold
weather can wear these parts out quickly, and they
can impact how efficiently your cabin heats up."
In order to check the blend door, Wagaman
advises cycling the fan on each setting as well
as checking all locations where air flows out to
ensure there is enough air output through each
blend door. This will help verify the system is
functioning properly.
A/C leaks
A/C is an important part of the HVAC system
year-round, so any A/C leaks could be potentially disastrous.
Jack Kelly, marketing strategist for Tracer
Products, a supplier of OEM leak detection products, explains the difficulty with finding leaks as
they can be very small. Pinhole leaks can range
from 0.00001" to 0.0004" in diameter.
"[Leaks] are devastating because they create an
'open system' that lets refrigerant out and contaminants in," no matter the size of the leak, Kelly says.

The longer a leak has been affecting the A/C
system, the higher the probability of moisture
having entered the system, which can cause
damage to other vital parts. For instance, Kelly
notes that moisture within the system enables
mold and mildew to form and potentially interfere with normal operation.
Early detection is key. The earlier a leak is found,
the less damage it can cause, and less money needs
to be spent on repairs.
The best way to find leaks quickly and efficiently before they cause too much damage is using a
blacklight with ultraviolet (UV) fluorescent dye,
Kelly says. A technician can easily find the leak by
examining where the UV dye fluoresces brightly
when activated by a high-intensity light.
Super-absorption
In the winter, if the driver begins to notice an
increase in humidity inside the cabin, this is likely
due to the truck's accumulator or dryer - depending on the A/C system's design - being "super-absorbed," says Brian Messenger, field service
manager at Mahle, an automotive parts supplier.
Inside the accumulator or dryer is a desiccant
bag that is designed to absorb residual moisture
in the system, Messenger explains. Once the bag
has reached its maximum capacity, the moisture
cannot be absorbed so it circulates throughout the
system, which increases the rate the refrigerant
boils inside the evaporator. This then increases
the low side pressure, meaning the evaporator's
surface temperature is greater than the 32 degrees
F it is meant to be. The driver feels this as humidity
in the cabin.
Messenger says an evacuation utilizing an
EPA compliant recovery, recycle, recharge (RRR)
machine is the only way to remove the moisture
from the A/C system. This will not only prolong the
life of the compressor, but also the lives of other
components within the system.
Fuel prime
Another potential issue to watch for is the cab
heater or coolant heater having lost its fuel prime,
say Dennehy and Stencil. This can happen when
heaters haven't been run frequently enough.
Fleets should advise their drivers to be patient
when turning on the heat if it hasn't been used
in a while as the start cycle can take up to five
minutes to complete.

HVAC maintenance

In addition to understanding what issues to look
for within trucks' HVAC systems, fleets must
perform system maintenance. It's better to stay
ahead of problems than find them too late.
"The most beneficial thing you can do is a
routine check by running through a checklist to
make sure the system's components are running
correctly," Bosch's Wagaman says. "That list should
include topping off all fluids, making sure that all
blowers are working properly, and checking each
blend door location to test for adequate air flow."
Coupled with those checks, fleets should also
look outside the HVAC system and check the engine
cooling system for any issues. Mahle's Messenger
suggests technicians verify the thermostat and

		»With heaters such as the
Airtronic from Eberspacher,
it is important to give
the system time to run
through its start cycle,
especially if the heat hasn't
been used recently.

mechanical fan clutch or electric
fans for the A/C condenser and
radiator are efficiently operating, as well as check the radiator
cap's pressure rating and ensure
there is no debris in the fins of Photo courtesy of Eberspacher
the condenser and radiator. This
promotes proper air flow for heat exchange and
engine coolant integrity.
In order for a technician to fully maintain a
vehicle's HVAC system they must have the proper certification.
"EPA regulations stipulate that all vehicles
requiring the removal of refrigerants be serviced
by a certified technician under Section 609 of the
Clean Air Act, and that all refrigerant be reclaimed
and recycled," say Michael Cicioni, HVAC application manager, and Ken Coventry, senior application technician for Webasto. Webasto is a
manufacturer of custom heating, air conditioning,
and sun roof solutions for a variety of applications,
both OE and aftermarket.
Wagaman also recommends ASE's training course on HVAC systems, which provides
technicians information as well as a test to get
them started on HVAC repairs and diagnosis.
Furthermore, he notes there is OEM-level training available which addresses repairs for specific
vehicle makes and models.
Armed with a checklist of components to test
and training and certification to make repairs, the
final items technicians need to maintain HVAC
systems are the appropriate tools and equipment.
Wagaman suggests the following set of tools to
assist with HVAC system maintenance:
Ü	Diagnostic tool to pinpoint system issues
Ü	Handheld leak detector
Ü	Digital voltmeter
Ü	Pressure tester
Ü	RRR machine to assist with refilling HVAC
system refrigerant
Refrigerant management systems (RMS) are
another beneficial HVAC tool for technicians,
Cicioni and Coventry note. The RMS setup gives
technicians the ability to check pressures, recover
refrigerant, and recharge the system.
With the proper tools and knowledge in hand,
fleets can prevent many HVAC issues, avoiding
future repairs and downtime.

Conclusion

When it comes to HVAC system winter preparation, fleets must inspect and perform any needed
maintenance on the heating system as well as the
A/C system. To do this, technicians need to have
a full understanding of potential issues, training
and certification to accurately diagnose and repair
the system, and the necessary tools and equipment to provide any maintenance is needed.

October 2020 | VehicleServicePros.com

35


http://www.VehicleServicePros.com

Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance

Uptime: How Fleets Can Connect with Tech Schools
Editor's Note: The Aftertreatment Blues
Keys to Maximizing Trailer ROI
Best Practices for Maintaining Hydraulic Braking Systems
Solving the Parts Puzzle
Contending with Accelerated BEV Tire Wear
Cold Weather HVAC Considerations
Management: CMMS Marketplace
Economic Outlook: Signs of Economic Recovery
Diagnostics: Choosing the Right Diagnostic Tool for Roadside Triage
Fleet Parts & Components
Tools & Equipment
Classifieds
Guest Editorial: The Propane-Powered Alternative
Fleet Maintenance - 1
Fleet Maintenance - 2
Fleet Maintenance - 3
Fleet Maintenance - 4
Fleet Maintenance - 5
Fleet Maintenance - 6
Fleet Maintenance - 7
Fleet Maintenance - Uptime: How Fleets Can Connect with Tech Schools
Fleet Maintenance - 9
Fleet Maintenance - Editor's Note: The Aftertreatment Blues
Fleet Maintenance - 11
Fleet Maintenance - Keys to Maximizing Trailer ROI
Fleet Maintenance - 13
Fleet Maintenance - 14
Fleet Maintenance - 15
Fleet Maintenance - 16
Fleet Maintenance - 17
Fleet Maintenance - 18
Fleet Maintenance - 19
Fleet Maintenance - Best Practices for Maintaining Hydraulic Braking Systems
Fleet Maintenance - 21
Fleet Maintenance - 22
Fleet Maintenance - 23
Fleet Maintenance - 24
Fleet Maintenance - 25
Fleet Maintenance - Solving the Parts Puzzle
Fleet Maintenance - 27
Fleet Maintenance - 28
Fleet Maintenance - 29
Fleet Maintenance - 30
Fleet Maintenance - 31
Fleet Maintenance - Contending with Accelerated BEV Tire Wear
Fleet Maintenance - 33
Fleet Maintenance - Cold Weather HVAC Considerations
Fleet Maintenance - 35
Fleet Maintenance - Management: CMMS Marketplace
Fleet Maintenance - 37
Fleet Maintenance - 38
Fleet Maintenance - 39
Fleet Maintenance - Economic Outlook: Signs of Economic Recovery
Fleet Maintenance - 41
Fleet Maintenance - Diagnostics: Choosing the Right Diagnostic Tool for Roadside Triage
Fleet Maintenance - 43
Fleet Maintenance - 44
Fleet Maintenance - 45
Fleet Maintenance - Fleet Parts & Components
Fleet Maintenance - 47
Fleet Maintenance - 48
Fleet Maintenance - 49
Fleet Maintenance - 50
Fleet Maintenance - Tools & Equipment
Fleet Maintenance - Classifieds
Fleet Maintenance - 53
Fleet Maintenance - Guest Editorial: The Propane-Powered Alternative
Fleet Maintenance - 55
Fleet Maintenance - 56
Fleet Maintenance - A1
Fleet Maintenance - A2
Fleet Maintenance - A3
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