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Heavy Duty

Helping your customer understand their A/C repair

December 16, 2021

To help service shop owners, MACS has created a 30-page consumer guide for your customers that explains how their car’s engine cooling system and air conditioning system works. “Getting to know your car’s air conditioning and engine cooling system,” details how these vital climate systems work and why they may require an extensive repair.
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The pulse width modulated duty cycle signal

December 7, 2021

Several years ago, when vehicles using these compressors were just starting to show up at shops for service with some regularity, we were searching to find some detailed information about their behavior to use in clinics.  There was not a lot of it available, so we borrowed several vehicles and did some videos.  The following are some clinic slides produced from one of those videos.
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Diagnosing electronically controlled compressors

November 30, 2021

When preparing to conduct diagnostics on a system using an electronically controlled variable displacement compressor, the diagnostic process needs to focus on four areas.
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Exploring electronically controlled variable displacement compressors

November 23, 2021

Electronically controlled variable displacement compressors (ECVDs) have been in use now for over 15 years.  However, there are a lot of technicians in the field who have very little knowledge about them and their operation.
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EPA releases Automotive Trends Report

November 19, 2021

Vehicle enthusiasts may want to check out the U.S. EPA's newly released Automotive Trends Report.
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Electronically controlled variable displacement compressors

November 16, 2021

what if" this system used an electronically controlled variable displacement compressor instead of the pressure controlled variable displacement compressor?   What would the results be?
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Meet MACS member, Tom Lech

November 8, 2021

Stationed in San Francisco, California, Thomas Lech has maintained a bustling business for almost three decades. Lech Auto Air Conditioning has been busy for 365 days a year from opening at 7 a.m. to closing at 7 p.m. for the last 27 years, with summertime only increasing the demand for the shop’s services.
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What do you know about the fixed displacement piston compressor?

November 2, 2021

What do you know about the fixed displacement piston compressor? 
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J1587/J1708 and J1939 data line diagnostics

October 27, 2021

Modern heavy-duty equipment is basically comprised of computers with operating units attached. In short, it is a multiplexing system that replaces traditional power distribution devices with ECUs that communicate electronically over the vehicle datalink.
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The concept of superheat

October 19, 2021

We illustrated the concept of superheat in last week's article by boiling water and superheating steam in a moonshine still. This week we will apply this concept to refrigerant in an air conditioning system.  The still has been replaced with an evaporator. 
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