MACS Monthly Newsletter - 2022 - JAN1

Service Reports
MOBILE AIR CLIMATE SYSTEMS ASSOCIATION ©
By Richard Hawkins, MACS Technical Correspondent
When approached by MACS about writing an MSR, one
of my first thoughts was: What should the subject be? And
the answer to that question was pretty easy: It should be
on the importance of knowing the location of service ports
on A/C systems and understanding the importance of applying
that information to diagnostics. That was because I
participated in a webinar with MACS' manager of service
training on that very subject. To view the webinar, you can
go to the following link: https://youtu.be/KkOokPg7zeg
Having worked on an A/C tech line for over 12 years,
I've had the opportunity to have a lot of interesting conversations
with technicians who were experiencing some
extremely tough performance problems, sometimes with
some really unusual pressure readings. When having
these conversations, one of the first questions posed to
them was: Where are the locations of the service ports?
After asking this question a number of times and listening
to the answers, it became obvious early on that a very
large percentage of technicians didn't have any understanding
of the importance of this question, hadn't given
any thought to it and actually had trouble providing that
information. To provide some insight into this, let's take a
look at how a conversation might go.
Me: Those are some pretty usual pressure readings you
just provided, and some detailed information is needed to
dig in to this. Can you tell me where the service ports are
located?
Technician: Sure, the high side service port is located
on the high side hose, and the low side port is located on
the low side hose.
Me: That's a start, but I need to know the PRECISE location
of those ports.
Technician: OK. Let me go look under the hood (and
a minute or so later he'd come back and say), the high
side port is located on the high side line, up near the front
of the car, and the low side port is located back near the
firewall.
Me: That still doesn't provide the precise location of the
service ports as you have a discharge line and a liquid line
MACS Service Reports is the official technical publication of the
Mobile Air Climate Systems Association, P.O. Box 88, Lansdale, PA
19446. The material published in MACS Service Reports expresses
the views of the contributors and not necessarily that of MACS. Every
attempt has been made to ensure
January 2022
1
January 2022
Where are the service ports located? (And why does it matter?)
on the high side and sections of both can run along the
front of this car. On the suction line, just knowing that it is
located near the firewall doesn't tell us if it is closer to the
block valve or the compressor and it also doesn't provide
any information on whether there might be a rubber hose
located between it and those components.
So, let's try approaching this a little differently. Let's forget
about the car and focus on just the A/C system only.
The A/C system is a closed loop system that has the major
components connected to one another with hoses and
lines. The compressor is connected to the condenser by
the discharge line, and the condenser is then connected
to the drier by the liquid line (and then another liquid line
runs from the dryer to the block valve). Is that high side
service port located on the discharge line or the liquid
line?
Technician:The discharge line.
Me: OK. Now is it located closer to the compressor or
the condenser?
Technician: Closer to the condenser.
Me: OK, so that means there is a rubber hose between
the service port and the compressor. Approximately how
long is that hose?
Technician: That's right. The hose is about 2 feet long.
Me: Is there any rubber hose between the service port
and the condenser?
Technician: No, there is about a two-inch piece of metal
line between the service port and the condenser.
Me: Now let's move on to the low side port. The suction
line runs along the firewall and connects the block valve
to the compressor. Is the low side service port closer to
the block valve or the compressor?
Technician: It's located closer to the block valve.
Me: Is there any rubber hose between the service port
and the block valve?
Technician: No. There is a short piece of metal line between
the service port and the block valve. It's about 3
inches long.
Me: How long is the rubber hose from the service port
the accuracy of the content of MACS Service Reports. MACS, however,
will not be responsible for the accuracy of the information published
nor will MACS be liable in any way for injury, labor, parts or
other expenses resulting from the use of information appearing in
MACS Service Reports.
MACS Service Reports
https://www.youtube.com/watch?v=KkOokPg7zeg
MACS Monthly Newsletter - 2022

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