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HD/Off-road/Other Instructors

Back to school bus A/C

September 1, 2021

Since it’s September (and another school year is upon us), we’re going to look at what’s so different about school bus A/C as compared to the more common automotive-type systems.
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Field study: Incorrectly installed condensers

August 10, 2021

I have handled numerous tech calls involving older GM trucks with incorrectly installed condensers.  In preparation for this series of MACS blogs, I discovered a salvage truck with one of these condenser repairs.  This gave me the opportunity to duplicate the incorrect installation and look for pitfalls and solutions.
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Finding right side up

August 3, 2021

Most condensers have different fittings on the inlet and outlet.  The locations of the inlet and outlet on most condensers will not allow lines to be connected incorrectly, even if the fittings do happen to be the same size.  Lastly, the designs of the mounts on most condensers prevent a unit from being installed upside down.  However, none of these characteristics apply to the condenser the technician had installed. 
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What is your temperature testing data telling you?

May 18, 2021

If air conditioning systems were transparent where we could see inside them, then diagnostics would be faster and easier. We could look at the systems and see things right away that affect system operation, like restrictions and liquid levels in evaporators and condensers.
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Temperature Matters

May 11, 2021

In addition to having good contact with connectors and getting accurate readings, there are some other important things to remember when doing temperature testing.
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Pass the temperature probe

May 4, 2021

The first step is to run the A/C system for a few minutes to let it stabilize. Then both probes should be connected side by side at both points that will be temperature tested in the system. For example, if you were testing the temperature drop across the condenser, this would need to be done on both the discharge line and the liquid line.
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Are you using the right tools for mobile A/C repair?

April 30, 2021

Your shop’s R-134a recovery/recycling/recharge (R/R/R) machine is in well-maintained condition. You have an R-1234yf gauge manifold set and an R-1234yf machine is on order; should arrive shortly.
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Contact counts in temperature testing

April 27, 2021

Proper contact is vital when connecting to A/C lines using the contact type temperature thermometers. To determine if I am getting good contact, I always like to place both connectors side by side on the same line and observe the temperature readings.
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MACS Mobile A/C Update Webinar Now Available On Demand

April 22, 2021

Every year the Mobile Air Climate Systems Association creates a special mobile A/C update clinic to help working technicians keep up with the rapidly changing mobile A/C service and repair...
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The pressure is on

April 19, 2021

By appearance, radiator caps seem to be a simple device. Yet, many technicians do not understand the cap’s real function
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Temperature testing accuracy

April 13, 2021

Temperature readings can be easily used to determine if an orifice tube system might be undercharged, and they can also be used to charge an orifice tube system. But if the readings are not accurate, all they are going to do is cause you problems.
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Avoiding an oily situation

April 6, 2021

If you own a mobile A/C repair shop this is when you start to gear up for it, by replenishing your parts inventories and an important segment of those inventories is compressor oil.
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