Back to basics

by Steve Schaeber

There is no doubt that when it starts getting hot outside, your shop gets slammed with customers asking for help with their A/C systems. Same thing happens here at MACS, except we get slammed with A/C tech support calls.

Steve Schaeber

Most calls are really nothing special to talk about. Refrigerant charge amount, oil type and sensor locations are pretty common complaints, particularly for odd ball vehicles and trucks with limited information resources (and technicians unfamiliar with a particular make / model / system). We also get lots of requests for wiring diagrams and pressure gauge troubleshooting help. Plus, there’s many not-well-known TSBs that seem to keep coming up (Ford Escapes come to mind here).

Every once in a while, I get a tech call from one of our local member shops near MACS HQ. When it’s a really tough problem, I like to stop by and check it out for myself and (of course, I wear a mask and practice social distancing, in light of how things are today). (Read More)

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Understanding data lines (Part I)

By Larry Turay

Data lines and multiplexing have been with us in the heavy-duty world since 1990. The increased use of ABS, electronic ICUs, and automated transmissions to name a few, led the way that made the use of electronic control necessary for proper operation. Increased government regulations and tighter emission controls have led to updates and ongoing changes. Mainly with the introduction of emission controls; EGR, Aftertreatment, DEF and generic engine DTCs. A quick refresher on what multiplexing and data management is in order.

Larry Turay

Multiplexing is the combining of multiple signal outputs and switch or sensor inputs on a common circuit in order to reduce wiring complexity. Other advantages include automatic configuration of the vehicle for driving conditions, improved troubleshooting, customized parameters and configuration. heavy duty applications will use various data lines including J1708/J1587, J1939, and CAN that depend on multiplexing to operate.
Beginning with electronic engine controls introduced in 1990, the J1708/J1587 data line was used to communicate with the engine controls. Its purpose was primarily to convey fault codes and instrumentation. J1708 was the hardware standard for wire size, diagnostic connector, bus configuration, and so forth. J1587 was the communication standard, 8 bits per byte, 9.6 kbps, and a standardized language format. It is a bus style datalink using junction blocks. The J1708 datalink is identified by its green and orange twisted pair wiring. It runs at a slow rate of 9.6 bps, which was sufficient for its original purpose; transmit fault codes to a common connector to diagnostic tools. However, it soon became overburdened by its communication load. It was replaced for a short time by the J1922 datalink until the J1939 datalink was developed to support the increased datalink speeds. It continued to be on vehicles until 2016. (Read More)

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Are you a diagnostic detective?

By Pam Oakes, SME automotive professional

If you consider yourself a diagnostic detective see if you can solve this cooling system mystery before the end of the article!

Cooling Corner: The mystery of the 2008 Dodge Charger

Customers drive into our shops for maintenance, tires and corrective repairs. But every now-and-then even the most seasoned techs get a surprise. This is one of those times. 

While waiting for the car to cool-down, it was time to talk to the customer. The “20-Question” game is always an interesting exchange between the vehicle owner and the tech. Sometimes you get the background, other times just a bunch of “I don’t knows.” This time, the driver was a seasoned vehicle owner. He understood the “why” of the questioning and answered quickly. The take-away from the talk: He thought he saw antifreeze on his garage floor. He said that he topped-off the reservoir with water since he didn’t have any chemistry on-hand. But, he added, just about a cup-full. No more. (Read More)

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The 2020 September/October Action magazine issue is out!

School bus A/C service and technology

By Jerry Lemon, MACS Technical Correspondent

School is back in session, to some extent anyway, in most parts of the country. Now our thoughts turn to servicing the air conditioning on the buses, which are generally filled with up to 72 students. Full-sized school buses feature a mix of configurations from various manufacturers who try to keep the interior of a school bus comfortable in a wide range of operating conditions. Many rural school boards tend to run older buses, resulting in a number of challenges regarding servicing their systems, not the least of which is cost. These buses were likely originally equipped with the least expensive system available, not necessarily a system that even performed to the required standard. This story features an excursion through a complete refit/upfit for one of the older buses from a school district east of Dallas, Texas.

First, some background on the bus. This International bus came with a locally installed A/C system from a known supplier of school bus A/C systems. The district had purchased a number of these arrangements over the years and didn’t realize they performed poorly until they compared them to newly purchased Thomas bus systems, installed with the OEM supplied MCC air conditioning units. MCC purchased the Carrier line a number of years ago, and the basic design has not changed. They are the selected assembly line installed system for Thomas Bus. So, when the district purchased the Thomas buses, they compared the A/C performance to their existing buses … they found the existing buses were lacking. Although the district had tended to do all their own maintenance over the years to keep the A/C systems operating, they quickly realized this fix was beyond their capabilities. (Read More)

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School bus mobile A/C service and repair

The September/October 2020 issue of ACTION magazine is all about school bus A/C.

Watch for it, coming soon! Visit our main website at

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Spend some time with MACS president and coo Elvis Hoffpauir

Hello, and Welcome to MACS Worldwide’s YouTube Channel. We’re glad you’re here! Elvis Hoffpauir Pioneer Experience MACS History! Elvis Hoffpauir, MACS president and chief operating officer, was presented with a 2019 MACS Pioneer Award at the MACS 2020 Training Event & Trade Show at the Gaylord Opryland Resort in Nashville, Tennessee on Thursday, February 20, 2020. This interview with Elvis was conducted by Steve Schaeber, MACS technical editor and manager of service training, via Zoom video meeting on May 14, 2020. Elvis has been involved with MACS since its inception, and organized all of the meetings, training events and classes that MACS held over the years. Elvis has authored many of MACS publications, including its Section 609 Technician Training manual. Elvis is current member of SAE’s (Society of Automotive Engineers) Interior Climate Control Standards Committee. In his younger years he served in the US Air Force, and was a writer and editor for several newspapers in Louisiana where he grew up. Elvis also worked for IMACA (the International Mobile Air Conditioning Association) and NARSA (the National Automotive Radiator Service Association) prior to the formation of MACS. He also played a key role in the formation of the Society during it’s developmental years of 1979 through 1981. Elvis attended school in Crowley, LA and the University of Southern Louisiana, now called the University of Louisiana at Lafayette. He served in the United States Air Force too. He received a 2006 Climate Protection Award from the US EPA for his work on the IMAC (Improved Mobile Air Conditioning) program during the early 2000s. He also received many journalism awards. For more information about MACS Worldwide, the annual MACS Training Event and Trade Show, and MACS Section 609 Certification program for mobile A/C service technicians, please contact MACS Worldwide at our website Thanks! Founded in 1981, MACS is the leading non-profit trade association for total vehicle climate and thermal management. Since 1991, MACS has assisted more than 1 million service technicians to comply with the 1990 U.S. EPA Clean Air Act requirements for Section 609 certification in refrigerant recovery and recycling to protect the environment. The Mobile Air Conditioning Society (MACS) Worldwide’s mission is clear and focused–as the recognized global authority on mobile air conditioning and heat transfer industry issues. For more information, please contact: © 2020 Mobile Air Conditioning Society (MACS) Worldwide Lansdale, PA (215) 631-7020

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Connector testing and repair

By Larry Turay

In the previous issue, wiring harness issues were discussed. The subject of harness issues continues with a look at connectors and connections either in the harness or at a control module or component. Often a component or module is replaced without resulting in any change in the condition or elimination of the DTCs. In addition to the wiring harness, the connectors must be inspected carefully and tested. It is recommended that technicians use the listed resources found in the service manuals whenever appropriate to assist them in the diagnostic process. Circuit testing procedures are found in the troubleshooting section of the service information references.
It is a good practice to have a procedure to follow when troubleshooting electrical problems to help find the problem as quickly as possible with the least amount of time and disassembly.

Larry Turay

A proven diagnostic process is the 7-step diagnostic test. The 7 troubleshooting steps are:
• Verify the complaint.
• Obtain pertinent information.
• Determine potential causes.
• Narrow the list of potential causes.
• Test to determine the root cause.
• Repair the root cause and any progressive damage it caused.
• Verify the complaint has been eliminated.
ATTENTION! Keep in mind, when applying pertinent information, use both the OEM and VENDOR data.
Using the service manual information, determine and investigate the following circuit characteristics. Though the symptoms may vary, basic electrical failures are generally caused by:
• Loose connections: open/high resistance in terminals, splices, connectors and
• Improper connector/harness routing: assembly, opens/shorts and high resistance in
terminals, splices, connectors and grounds.
• Corrosion and wire damage: opens/shorts and high resistance in terminals, splices,
connectors and grounds.
• Component failure: opens/shorts and high resistance in relays, modules, switches,
• Aftermarket (vendor) equipment: installation of non-OEM equipment may affect the
normal operation of other electrical systems. (Read more)

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Does your business have a social media policy?

If the last few months have taught us anything, it’s that without clear-cut policies in place, our world can quickly devolve into a chaotic spin. From extended personnel leave to sanitation and cleanliness, to business interruption policies, owners and managers have had their hands full jumping from one issue to the next. Unfortunately, I’m about to dump one more thing on your desk: your business’s Social Media Policy.
Understand that a social media policy is more than a list of do’s and don’ts. It’s a living document designed to outline the expectations and responsibilities of the people posting to your company’s social media accounts, as well as rules of conduct for the public on what is allowed on your business social media pages. This is important for several reasons:
● A business can maintain its brand identity across multiple channels.
● Legal and regulatory issues are handled with awareness and sensitivity.
● Security breaches can be prevented.
● A full-blown PR crisis can be potentially averted.
● In the event of a crisis or breach, staff can react and resolve a matter quickly.
● Employees and ownership are educated about their own social media responsibilities.
● Employees are encouraged to grow and amplify your business’s message.
Creating the policy

Angie Chabot, AAM

Like any business document, it’s best to start a Social Media Policy by covering the basics, including:

  1. What are employees’ roles and responsibilities in creating, posting and responding to social media on the company’s accounts?
  2. Who has access to these accounts?
  3. How often do passwords get changed?
  4. How often will social media managers get trained?
  5. What devices can be used to post on the company’s social media?
    From there, the next important issue to tackle is a code of conduct. Let’s assume your employees are trustworthy from this aspect, but the real concern is preventing your business from becoming the victim of trolling and smear campaigns.
    A social media page should be a place to share positive and informative content about your organization, and this policy should be communicated to visitors. State on your social media pages that your company reserves the right to delete any posts that contain material that is defamatory, harassing, illegal or off-topic. Provide the customer service contact information in your code of conduct policy, and remind followers that you are available to help and offer personal service offline.
    Staying within the law
    Your policy should also outline specific content requirements that will protect the organization from running afoul of the legal system, including:
    ● Copyright: Not everyone understands that using third-party content without approval is a breach of copyright law. Ensure staff have a clear understanding of what tools are available to them so they aren’t searching for artwork or other content that isn’t licensed.
    ● Privacy: Do all employees know how to handle customer information? Make sure your people don’t run into trouble without even realizing they’ve stepped over the line.
    ● Confidentiality: Do employees understand that certain internal information about your organization should not be discussed publicly? Even if staff sign nondisclosure agreements, they should be aware of the consequences of disclosing information on social media that the organization considers private. (Read more)
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Comparing the 2020 COVID-19 and 2003 SARS Pandemics

By Ward J. Atkinson, MACS Technical Advisor

When COVID-19 first appeared in the news, the U.S. general population wasn’t very concerned. Many assumed that like the SARS pandemic, it would only affect relatively few people.

The 2002–2003 SARS outbreak lasted about eight months. The World Health Organization declared that SARS was contained on 5 July 2003. During that time period, over 8,000 people were infected, and at least 774 died in 29 different countries and territories worldwide.

The COVID-19 has proven to be much more severe and it’s not over yet. This virus raises serious questions about the best way to clean a vehicle prior to service (protecting the service technician) and the best way to clean it after service (to protect the customer). 

The coronavirus that causes COVID-19 mainly spreads from person to person. When someone who is infected coughs or sneezes, they send droplets containing the virus into the air. These droplets can also be expelled when laughing or talking loudly in a crowded area when being close to others. You may also catch the virus if you touch a surface or object that has the virus on it and then touch your mouth, nose, or eyes.

Current evidence suggests that SARS-CoV-2 may remain viable for hours to days on surfaces made from a variety of materials. With different kinds of hard surfaces (such as metal, doorknobs, jewelry, silverware, drinking glasses, mirrors, and windows), the virus may last for up to 5 days. With plastic surfaces (such as milk containers, detergent bottles, vehicle interior, backpacks, elevator buttons), the virus may last up to 2 to 3 days.

Transmission of the virus through the ventilation and filtration systems, while possible, is less likely.

To reduce your chance of catching or spreading the new coronavirus, wear a mask to reduce possible person-to-person transmission and clean and disinfect common surfaces and objects at least every day.

Due to the complexity of the COVID-19 subject, the best approach is that the service technician needs to take all the precautions that they are comfortable to protect themselves when working on the vehicle.

Coronavirus and Temperature

Coronaviruses generally don’t live as long in higher temperatures and humidity levels as compared to cooler, dryer conditions. Researchers are studying exposure to heat, cold, or sunlight and how long the new virus lives on surfaces.

SARS was proven to be killed at 56°C (132.8°F) in 15 minutes according to the WHO (World Health Organization). 

The coronavirus can live for hours to days on surfaces. How long it survives also depends on the material the surface is made from. At this time there is no factual information on the required temperature and conditions required to kill SARS-CoV-2 on the various cabin material surfaces.

The family of viruses that includes the one that causes COVID-19 can live on some of the surfaces you probably touch every day.

*Researchers still have a lot to learn about the new coronavirus. But you’re probably more likely to catch it from being around someone who has it than from touching a contaminated surface. Refrence:

The U.S. EPA provides the following guidelines (

6 Steps for Safe & Effective Disinfectant Use

Step 1: Check that your product is EPA-approved. Find the EPA registration number on the product. Then, check to see if it is on EPA’s list of approved disinfectants at:

Step 2: Read the directions. Follow the product’s directions. Check “use sites” and “surface types” to see where you can use the product. Read the “precautionary statements.”

Step 3: Pre-clean the surface. Make sure to wash the surface with soap and water if the directions mention pre-cleaning or if the surface is visibly dirty.

Step 4: Follow the contact time. You can find the contact time in the directions. The surface should remain wet the whole time to ensure the product is effective.

Step 5: Wear gloves and wash your hands. For disposable gloves, discard them after each cleaning. For reusable gloves, dedicate a pair to disinfecting for COVID-19. Wash your hands after removing the gloves.

Step 6: Lock it up. Keep lids tightly closed and store out of reach of children.

List N from the EPA: Disinfectants for Use Against SARS-CoV-2

All products on the list meet EPA’s criteria for use against SARS-CoV-2, the virus that causes COVID-19.

The product container must have the EPA registration number and that human coronavirus is listed as a target pathogen.

These products are to be used only on hard nonporous surfaces.

Note: Inclusion on this list does not constitute an endorsement by EPA. Additional disinfectants may meet the criteria for use against SARS-CoV-2. EPA will update this list with additional products as needed.

Product Label: The companies list their product range and basic chemicals (active ingredients) used in the products.

The Current EPA List N: as of July 1, 2020 has over 430 products entries.

Figure 1: Spray Cleaners. This product, available at stores, is not currently listed to kill SARS-CoV-2.

Other Disinfecting Processes

Other disinfecting processes have been discussed that may have limitations and personnel safety concerns.

Infrared: May not be able to reach all vehicle surfaces for disinfecting. Proper use instructions must be followed for all approved sources.

Ozone generated air cleaners: Some studies show that ozone concentrations produced by ozone generators can exceed health standards even when one follows the manufacturer’s instructions. Many factors affect ozone concentrations including the amount of ozone produced by the machine(s), the size of the indoor space, the amount of material in the room with which ozone reacts, the outdoor ozone concentration, and the amount of ventilation. It is difficult to control the ozone concentration in all circumstances. Reference:

Use of High Temperature for Disinfecting

In general it is difficult to raise, in a closed vehicle, all cabin material surface temperatures to at or above 133°F (which is the temperature that has been shown to kill SARS virus by the WHO) using sun soak or sun and supplemental heat from the vehicle heater.

Coronaviruses generally don’t live as long in higher temperatures and humidity levels than in cooler, dryer conditions. Researchers are studying exposure to heat, cold, or sunlight and how long the new virus lives on surfaces.

There have been various proposals of using solar and/or vehicle heaters to increase interior cabin surfaces in temperature.

Solar and vehicle heating: Solar heating is limited to only warming surfaces in direct sun to high temperatures. Solar heating (radiation intensity) is affected by location and weather conditions within the US area.

Use of vehicle soak procedures by raising the vehicle interior temperature cabin surfaces have many issues: Vehicle cabin temperature can be increased using the vehicle heater. It is difficult to raise all cabin surfaces to same or potential required temperature to kill the virus. Use of solar and/or vehicle heater to raise cabin surface temperatures is not practicable to kill the virus.

Vehicle Test Results

The test results of these procedures of heating a passenger car cabin compare heating and solar is found below in Figures 2 to 7 and Charts 1 and 2. Eight cabin temperatures were recorded during a 78°F to 82°F day. It is important to note that the vehicle had a rear seat A/C outlet, which affected rear seat surface and floor temperatures when the vehicle heater mode was used.

Chart 1: Night Time Data: Temperature locations that reach 133°F.
Figure 2: Vehicle Breath: Air from A/C Panel Outlet Temperatures

* Note the 133°F marker on each graph.

Figure 3: Door Arm Rest: Center Console: Center of Instrument Panel Surfaces
Figure 4: Center of Rear Seat: Front and Rear Carpet Surfaces
Chart 2: Day Time Data: Temperature locations that reach 133°F.
Figure 5: Air from A/C Panel Outlet: Vehicle Breath Temperatures
Figure 6: Center of Instrument Panel: Center Console: Door Arm Rest Surfaces
Figure 7: Center of Rear Seat: Front and Rear Carpet Surfaces

Heater operation set for maximum temperature heat mode, airflow set for instrument panel A/C outlet air distribution. Vehicle equipped with automatic temperature control having rear seat A/C air outlet.

Automotive Service Concerns

The folloing excerpts are from an April 2020 letter the Mobile Air Conditioning Society (MACS) sent to U.S. regulatory agencies:

It is estimated in 2020 there are 287.3 million vehicles operating on roads throughout the United States. These vehicles are operated by more than 227.8 million motorists, serviced by 763,700 auto service technicians and mechanics at 166,000 different automotive service facilities in the USA, all needing protection from the coronavirus.

Each vehicle cabin is a small, self-contained, climate-controlled environment, which restricts movement, requires close contact of occupants, and repeated touching of interior surfaces.

Air conditioning panel outlets are close to occupants’ faces, directing air at the occupants face, mouth and nose.

The instrument panel surface can become contaminated by breathing/coughing of front seat occupants. Panel A/C outlets airflow will pull air from the panel surface, mixing it and delivering it toward the cabin interior.

The climate control system in vehicles present different challenges, as compared to a residential environment. Operation of the system allows the selection of 100% exterior (outside air) and cabin recirculated air. In the recirculated mode, system A/C designs for the amount of outside airflow can vary. The number of air exchanges per hour may be less than many household applications. Typical industry requirements, for a home, are in the range of 4 to 6 air exchanges per hour. Some mobile A/C systems operating in the MAX cooling mode (recirculated air) have provided at least 6 exchanges per hour.

The velocity of airflow directed onto the occupants is usually much higher than in residential systems.

There are a large variety of filters in some mobile A/C systems that require servicing and some vehicles have no air filter.

There is also concern for cleaning vehicles after the vehicle has been entered by others, for oil changes, for maintenance activities or valet parking.

Cleaning Procedures and Chemicals

The following is a collection of COVID-19 information on cleaning vehicles that is available to the public from different sources.

It is notable that references are made.

  • “Consult the cleaning information provided by the vehicle manufacturer”
  • Caution on using full strength bleach or hydrogen peroxide. They can kill      coronaviruses on surfaces, but may damage upholstery and interior trim.
  • Some general information listed have been suggested since March 2020.
  • New information and products may provide information and procedures for sanitizing vehicles and should be considered for vehicle cleaning.
  • Alcohol solutions that contain at least 70% alcohol are effective against coronavirus, according to the CDC.
  • Never combine cleaning chemicals as doing so may lead to toxicity.
  • Testing an out of sight surface with the selected cleaning agent is advisable in case of possible damage.
  • Cleaning with a microfiber cloth materials may help remove dirt from surfaces.

One major supplier of automotive interior parts, indicate that their company’s products, “from plastic trim to painted chrome to imitation leather, have been tested to ensure they don’t degrade when exposed to pure isopropyl alcohol.”

Do not use ammonia-based cleaners on car touch screens, as they can damage their anti-glare and anti-fingerprint coatings.

“Friction from cleaning also participates in the destruction,” says Stephen Thomas, M.D., chief of infectious diseases and director of global health at Upstate Medical University in Syracuse. “You want to do the best with what you have, so even soap and water can chip away at the risk.”

Soap and water are safe for most car interiors including fabrics and older leather that may have begun to crack. Excess amounts of cleaning solutions, such as water and soap can result in soaking through the cloth surface into the seating material and the potential of future odor problems.

Vehicle High Touch Areas:

  • Car keys and fobs
  • Door handles and lock buttons
  • Steering wheel
  • Shift lever
  • Wiper and turn signal levers
  • Controls for touch screen accessory controls
  • Center console contents
  • Armrests
  • Seat belts
  • Headrest
  • Seat pockets
  • Handles
  • Seat adjusters

Wash your hands before and after driving

When outside the vehicle wear gloves. Contact of high traffic surfaces that are not disinfected, when opening and closing doors, keypads, signing charge card pads and fuel nozzle handle when pumping gas.

About MACS Worldwide

Founded in 1981, MACS is the leading non-profit trade association for total vehicle climate and thermal management. Since 1991, MACS has assisted more than 1 million service technicians to comply with the 1990 U.S. EPA Clean Air Act requirements for Section 609 certification in refrigerant recovery and recycling to protect the environment. The Mobile Air Conditioning Society (MACS) Worldwide’s mission is clear and focused–as the recognized global authority on mobile air conditioning and heat transfer industry issues.

It is a mission we have been fulfilling for our growing global membership and the industry in the following ways:

Providing accurate, unbiased technical training, and compliance programs for the mobile air conditioning and heat transfer industry.
Providing a forum for exchange of trade information on a regional, national and international basis.
Facilitating business between all segments of the industry.
Providing tangible value for members, such as product marketing, promotion and money-saving affinity programs.
Disseminating legislative, regulatory and trade information (including data, current developments and training materials).
Providing information on legislative and regulatory initiatives that affect the industry and advocate for the industry to legislative bodies.

Visit our website for more information or call (215) 631-7020.

And as always, Thanks for Reading!

Edited by: Steve Schaeber, MACS Technical Editor on 7/13/2020

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Over the road: Auxiliary power unit engine cooling systems

By: Joey Rosato, Director of Marketing at Texas Truck A/C, Inc.

Joey Rosato,
Texas Truck A/C, Inc.

As time goes on, Auxiliary Power Units (APUs) continue to play a larger role in the over the road trucking industry. Idle laws that vary state by state are placing restrictions on drivers across the nation. Because overnight idling to run the OEM AC system is now illegal in many places, the installation of an APU is required. Diesel APUs are the most popular solution to these restrictions, as they can provide heat, air conditioning, battery charging, coolant warming, and electrical power capabilities to drivers. These units are powered by small diesel engines, which can be run for extended periods of time while drivers are resting.
Extended run times create a unique challenge in keeping these diesel engines cool. APU engine cooling systems are not as complex as their automotive counterparts, but they operate in nearly identical fashions through the use of water pumps, cooling fans, thermostats, and various sensors/switches that collect data for the control module. The control module then uses the collected data to shut the engine down in low coolant, or high coolant-temperature conditions. Most APUs have fault code storage capabilities, and will display a fault code when these issues arise.
Without the proper function of these cooling systems, APUs are known to fail while displaying overheat codes, which render entire systems useless. A problematic component that often contributes to cooling system failure is the electric radiator/exhaust fan, which is known to succumb to wear and tear over time. Extreme vibrations and extended run times assemble to create a reduced life for components of this sort. One of the most common, but often overlooked signs that an electric fan is going bad is a reduction in RPMs. This can be caused by overheated/corroded wiring, faulty relay contacts, or simply a fan that is on its way out. The best course of action once an issue of this sort arises is to ensure that the fan has solid power and ground, all blades are intact, and a direction of rotation aligns with OEM unit specifications. If an electric fan checks all of these boxes, but doesn’t function properly, it’s likely time for replacement.
When changing this component, it is important to carefully select the proper OEM replacement, or equivalent to ensure component specifications are satisfactory. If the rotation of the replacement fan is not correct, the unit will overheat. Attempting to turn a “pusher” fan into a “puller” fan, or vice versa, by reversing the component polarity is a faulty practice, as the fan blades are designed to turn a specific direction for maximum output. This error commonly results in reduced airflow and component life. Best practices while installing the appropriate replacement part include the replacement of the fan relay, and any corroded electrical connections.
After necessary repairs and part installations are complete on the new electronic fan, it is important to check for possible secondary problems caused by the previous, faulty component. Issues to check for include coolant leaks, the necessity of a flush or refill, water pump belt/radiator cap condition, radiator/condenser cleanliness, and well-maintained electrical circuitry across the system. Making these checks after completing necessary repairs will help safeguard the proper function of the APU engine cooling system, and ultimately the entire unit, ensuring that over the road drivers can rest comfortably.

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