Get the MACS mobile A/C diagnostics app with your paid MACS membership


Nearly a year in the making, the MACS mobile A/C diagnostics app is now available. The MACS board of directors decided last fall that it was time for MACS to fully embrace current technology and push our information out to mobile devices for the benefit of all of our members. The app was created by MACS member and digital industry leader SHIFTMobility.

All MACS members will receive the MACS mobile A/C diagnostics app provided their membership renewals are paid.


The app is for both Apple and Android mobile devices and can be downloaded from your respective app store (MACS Mobile A/C Diagnostics). After the download, expect to be verified within 24 hours.

How does it work?

The MACS mobile A/C diagnostic app is a native app, meaning you have the ability to use many of the built-in features of your mobile device.


On the top of the screen, to the right of Mobile A/C Diagnostics, you will see a stacked bar icon.

Press it to access settings.

This is where you can change your password and add your business information.

Mobile A/C system specifications

The icons directly below the title, Mobile A/C Diagnostics, are used to identify/select the specific vehicle information you are looking for. For example: refrigerant charge.

  • Vin: Press the Scan Vin icon, type in the VIN and confirm.
  • Plate: Press Plate and enter the letters and numbers for the license plate along with
    the state.
  • Vehicle: Press Vehicle, select year, make, model, sub-model (if applicable), engine.

After completing the vehicle selection all available information is ready for selection. Simply touch what you are looking for.  Hint: Because this is a native app, all images are expandable by placing two fingers on the screen and spreading them apart.

Truck and off-road vehicle data

To access all available truck and off- road vehicle data simply touch the area where the title, Truck and Off Road Vehicle Data appears. You will be taken to the truck and off-road vehicle data library.  You can either browse for the data you are looking for or enter a key word to be presented with the available information. MACS members ATC, AGCO and T/CCI Manufacturing have provided pdfs of helpful reference data. Keep in mind that truck reference data is VERY HARD TO OBTAIN and MACS has exhausted all resources to acquire it. Our best resource was our member suppliers and we are grateful for what they have shared with us.

The best of all MACS resources have also been added to this app so you can have them in the palm of your hand for access.

MACS Service Reports

To access the MACS Service Reports archive, simply touch the area titled Service Reports.

Press the year and then the month. This allows you to view the entire issue of MACS Service Reports for that month and year.


To access past issues of ACTION Magazine, simply touch the area titled ACTION Magazine and select the issue you are interested in viewing. This allows you to view the entire issue.

Training Resources

To access training available from MACS simply touch the area titled Training Resources.  You will be taken to the MACS website where you can view all of the available resources.

Mobile A/C Service Checklists

To access the service checklists simply touch the area titled Mobile A/C Service Checklists.  You will be taken to a screen with multiple thumbnails.  Simply touch the thumbnail that interests you and it will become visible.  In the upper right corner, you will notice three stacked dots.  Touch the icon to be able to “Send,” “Open With,” “Download,” “Print” and “Report a Problem.” To print directly from the app, you must follow the steps to configure your printer.

Supplier Directory

To access the MACS Supplier Directory, simply touch the area titled Supplier Directory.  There you will find a list of MACS member suppliers along with a hyperlink which will take you directly to their website or a phone number if there is no website. Just touch the company you are interested in and off you go.

As always with all MACS member services, if you have any questions call the MACS office at 215-631-7020 x 0 or email

Once again you must be a paid member of MACS to access our app. Join us now!





Posted in #1234yf, ACtion Magazine, MACS Member, Mobile Air Conditioning | Tagged , , , | Leave a comment

HD and OTR vehicle service: Keep it clean

July/August 2017 MACS ACTION Magazine

It’s been said that cleanliness is next to godliness. This can also be considered gospel when servicing heavy duty (HD) and over-the-road (OTR) refrigeration. These systems operate in far more severe conditions compared to those installed in the lowly light-duty vehicle. All systems must be kept clean both inside and outside, which is a tall order for HD and OTR.

Take a moment to consider the annual cycle of an OTR system. It can sit for months in sub-zero weather and may be placed into 24-7 service when seasons change. Consider what happens to the system during its down time. While not operating, could the refrigerant leak out over time? If not leaking, could undesirables enter the system while idle?
Read the rest of this article  

Download the July/August 2017 MACS ACTION 

Join MACS Today

Posted in ACtion Magazine, MACS Member, Mobile Air Conditioning, Training | Tagged , , , , , , , , , | Leave a comment

Cool runnings

By Steve Schaeber, MACS Technical Editor

The main purpose of a thermostat is to help the cooling system regulate engine operating temperatures to within the manufacturer’s specification. This is normally done by first remaining closed to allow engine coolant to warm up, and then gradually open all the way as temperatures near spec. But sometimes this doesn’t happen, as in the case of a fully or partially stuck open thermostat.

When a thermostat sticks open, engine coolant is allowed to circulate without much restriction throughout the cooling system. This sounds great, and it’s important for this to happen after the proper operating temperature is reached.  However, if it happens too soon the engine coolant may not be able to reach a high enough temperature. This problem occurs because modern cooling systems are actually quite efficient, and are able to transfer a lot of heat from a lot of liquid in a relatively short period of time. When the coolant is not allowed to warm up fully, it basically circulates from the engine to the radiator and back to the engine, losing so much heat with each pass that it stays relatively cool.

Problems attributed to a cold running engine include lower HVAC heater output, engine performance issues and increased tailpipe emissions. But it also prevents the evaporation of condensation that forms on the inside of the engine block. If this water doesn’t burn off it can oxidize the metal (producing rust) and cause an oil sludge buildup in the bottom of the pan.

Engine oil is also affected by the thermostat, and it’s important for it to reach an operating temperature of approximately 190°F. Oil that is cold is not quite as viscous as the substance when it’s warm. Transmission oil coolers are also affected because they are generally in direct contact with engine coolant.

An easy way to determine if a thermostat may be stuck open is to simply monitor coolant temperature. Some vehicles have a dashboard temperature gauge, but many technicians prefer to use a scan tool with graphing capabilities. Begin when the engine is cold and connect your scan tool before starting the engine. Graphing the coolant temperature sensor PID will allow you to watch the thermostat to see what happens over time. If the thermostat is only partially stuck open, you may notice a rise in value to a relatively warm number, perhaps around 150°F. But if it’s stuck open all the way, temperatures may not increase much past 120°F.

Many PCMs will also monitor thermostat operation, illuminate the check engine light and produce a trouble code if there’s a problem. Ford uses P0125, Insufficient Coolant Temperature for Closed Loop Fuel Control, along with P0128 Coolant Thermostat (Temperature Below Thermostat Regulating Temperature). Issues could be related to slow warm up times, low coolant level, or sensor output issues, as well. Sensor readings may be double checked by using a mechanical thermometer or a thermocouple connected to a digital meter.

Posted in ACtion Magazine, MACS Member, Mobile Air Conditioning, Training | Tagged , , , , , , , , | Leave a comment

Thermocycle leaks

Radiator leaks are nothing new, and some technicians may initially blame a faulty part, poor construction or shoddy workmanship during installation when a leaker shows up in their bay, particularly when it’s a later model vehicle that has failed. But sometimes the radiator may be the victim of rapid coolant temperature changes caused by a faulty or rapidly degrading thermostat that is opening and closing too often.

When this happens, hot, then cold, then hot, then cold, then hot, then cold (you get the idea) coolant is sent from the engine block to the radiator, effectively shocking it back and forth from hot to cold and then back again, over and over. This rapid change is called thermocycling, and it causes radiator tubes to quickly expand and contract so much that they disconnect from the radiator’s side tanks, allowing coolant to leak out. It’s a failure similar to those found in the solder joints of copper pipes or on electronic circuit boards.

GM has identified similar issues in vehicles including certain 2014-2015 Chevrolet Silverado, Suburban, and Tahoe models, as well as the GMC Sierra, Yukon and Denali, and the Cadillac Escalade with 4.3, 5.3, or 6.2L engine. In a series of Technical Service Bulletins, which include #PI1513B titled, “Coolant Smell and/or Slight Leak at Radiator,” issued on November 30, 2016, GM presents comments made by customers, such as smelling coolant while driving or when outside the truck. These complaints may or may not include a coolant leak under the front of the vehicle.

GM recommends that technicians begin their diagnostics by inspecting the radiator for any signs of leaks, such as those that may exist where the flat radiator tubes meet the side header tanks. Particular attention should be paid to the four corners of the radiator, areas which may experience the most fluctuations. The cause could be related to excessive thermocycling of the cooling system,  brought on by excessive cycling of the thermostat.


Technicians’ initial conclusions are often an incorrectly constructed radiator , or a weak tube to header joint, which allows coolant to leak. In some cases, the technician may successfully replace the leaky radiator only to have the replacement fail after a period of time, ultimately causing the owner to bring the car back to the shop, The technician could assume the replacement radiator is also defective and  exchange it once more. But the actual root cause of the fault may be the thermostat, which if it cycles open and closed too often, can shock the radiator by sending out cool and hot coolant. Ideally the temperature of the cooling system should remain constant, or change slowly over time without rapid, frequent or excessively wide changes in temperature.

The final fix includes not only a thorough inspection and replacement of the radiator to solve the leak problem, but also changing out the thermostat, and of course, GM has an updated part number to address the overcycling.

Posted in MACS Member, Mobile Air Conditioning, Training, Uncategorized | Tagged , , , , , | Leave a comment

MACS mobile A/C diagnostics app is now available for download for MACS members

In response to MACS member needs and changing technology MACS has partnered with Shiftmobility to create the MACS mobile A/C diagnostics app for use on mobile devices. The app will include access to the MACS Service Reports and ACTION Magazine archives, checklists to aid system diagnosis, access to MACS member manufacturers and distributor suppliers and an extensive mobile A/C vehicle specifications library.

Vehicle reference specs will include:

A/C & Heater Service, A/C System Specifications, Component Location Diagrams – HVAC Systems Only, Cooling System Bleed, Diagnostic Trouble Codes – HVAC Systems Only, Miscellaneous Capacities – HVAC Systems Only, Radiator & Hose Replacement Procedures and Wiring Diagrams – HVAC Systems Only.

Only MACS members in good standing will have access to this APP. To access the MACS Mobile A/C Diagnostics app visit the Google play store for android devices or the iTunes store for Apple devices. One free download is included with MACS membership. Additional downloads are $60 each. For a larger overview and users guide click here.

After you choose the app, MACS will verify your membership and approve your use.

For more information email or call 215-631-7020 x 304.

Not a MACS member? Join here. 

Posted in #1234yf, Automotive, MACS Member, Mobile Air Conditioning, Training | Leave a comment

Today’s technicians need to be total climate control management forensic scientists  


MACS June ACTION Magazine is all about mobile A/C diagnostics!

By Peter Orlando, MACS Contributor

 Technicians need proper skills to work on today’s climate control systems. It is up to industry professionals to ensure they are service-ready and have all the necessary certifications and safety awareness training before they attempt any A/C service work on a vehicle.

We are required to perform a diagnostic system performance test to determine what diagnostic direction we will take on the problem based on the customer’s complaint. Many times, we need to determine up front if a problem is addressed by a Preliminary Inspection or TSB. If we don’t, we can waste many hours on a problem. Following proper OEM test procedures is essential for achieving a job well done, delivered on time and at the price agreed upon while making a profit. Read the rest of the story here.

Download the entire June 2017 MACS ACTION Magazine

Posted in #1234yf, ACtion Magazine, MACS Member, Mobile Air Conditioning, Refrigerants | Tagged , , , , , , , | Leave a comment

MACS Summer of Service Videos

Calling all MACS members! MACS is launching the summer of service videos!

Send us a short mobile A/C technical tip video less than 10 minutes that explains a service procedure or is educational and not overly commerical and we will post it on our website homepage for one week this summer.

You must send us an embed link and again not overly commercial it is fine to mention a product but we are looking for solid tech tips.

This is a great opportunity for MACS member companies to get more traffic for their service videos and help educate the industry.

Email your video embed link to

MACS reserves the right to refuse any video we deem not to be appropriate.

You must be a member of MACS to participate.

Posted in #1234yf, ACtion Magazine, Mobile Air Conditioning | Leave a comment

Honeywell opens new R-1234yf plant in Louisiana

Honeywell announced that it has started commercial operations at its new manufacturing plant in Geismar, La., to meet the growing global demand for its next-generation mobile air conditioning refrigerant. With this start-up, the plant has become the world’s largest site for producing HFO-1234yf, sold commercially as Solstice® yf.

Have you ever wondered what a refrigerant plant looks like? Here are some photos of their new operation courtesy of Honeywell.

Posted in #1234yf | Tagged , , , , | Leave a comment

Clinics, clinics and more mobile A/C clinics!

MACS has been busy training all around North America. Here are a few photos from the clinics…

MACS Mobile A/C Update Class in Bethlehem, PA with MACS Steve Schaeber

MACS heavy-duty mobile A/C class at Arctic Traveler with MACS Mike Bailey

MACS Mobile A/C Update Class in Waxahachie, TX at Tubes ‘n Hoses wit Jerry Lemon

Posted in Automotive training, MACS Member, MACS Training Event, Mobile Air Conditioning, Uncategorized | Tagged , , , , , , | Leave a comment

Do you have the right tools to repair mobile A/C systems?

Global Service Horizons


2017 MACS Worldwide Trade Show puts the future in plain sight

May I share something with you? Of all the automotive industry events I cover each year, it is the annual Mobile Air Conditioning Society Worldwide (MACS) Training Event and Trade Show that I most enjoy attending. Now let me tell you why.   Read the whole article

Download the May 2017 Issue


Posted in #1234yf, ACtion Magazine, MACS Member, Mobile Air Conditioning, Training | Tagged , , , , , | Leave a comment