Old School vs New Tool

If- “A man whose only tool is a hammer tends to treat everything like a nail.”

What happens when a technician’s only performance diagnostic tool is a set of refrigerant gauges?

Too many technicians think their gauges are the only tool they have or need to find out if an HVAC system is operating correctly.  And those technicians are just wrong.  Refrigerant gauges were made to put refrigerant into systems and to take refrigerant out.  They can also be used to help calculate superheat and subcooling. But refrigerant gauges only monitor a  single conditional variable   in the  operation of a cooling system.

Refrigerant gauges  don’t tell a technician very much about a systems operating performance… for one very simple reason …they were never designed to.

Refrigerant gauges became the go-to performance diagnostic tool by default … not by design.  Here are a few things your refrigerant gauges can’t tell you: They can’t  tell you how many BTU’s a system is producing or what SEER those BTU’s are being produced at.

They can’t tell you if the supply ducts are crushed so badly … or are so undersized that the system isn’t moving enough air.  And your gauges can’t tell you if the system is sucking in 140 attic air because there is a massive hole in the return air plenum or that the ducts static pressure is above  … the fan’s static capacity.


Then there’s the dirty evaporator coil problem.  Every technician and his helper has an opinion about when an evaporator is too dirty and when it isn’t … But neither of them have the necessary facts to make an informed decision about how dirty is too dirty … Let an evaporator get dirty enough and those refrigerant gauges may help … or they might just fool you into thinking the system is undercharged.


Then there’s the same problem with the dirty blower.  When is it too dirty?  Here’s another  good question.  What if the evaporator is not visibly dirty enough to pull and clean and the blower does not appear to be dirty enough … but their combined condition is having a serious downward effect on system performance?


What if everything is ok except the blower speed?  How far off does that have to be before it shows up on a set of gauges as something other than an over charge or an under charge?

As remarkable a tool as they are, even the refrigerant gauge can’t be used for everything.   We could … but we won’t … go into a discussion of how “proper refrigerant charge” is dependent on outdoor ambient conditions, indoor air flow, and indoor humidity and temperature.

And if these reasons aren’t enough to motivate contractors and technicians to give up using the wrong tool for the right job … there  is an even better  reason to stop using refrigerant gauges for something they were never intended to do.



     Which requires less time?

A)  Connecting a set of refrigerant gauges and taking a superheat or sub cooling reading … and perhaps making a visual inspection of the blower wheel and evaporator coil … or

B)   taking three temperature readings?

    Using Total Performance Diagnostics is almost too easy …

1. You gather three temperature readings.

2. You input those readings into the program.

3. If the system report is within an acceptable range of operation … you know the air flow is within range … you know the refrigerant charge is ok … you know the metering device, compressor, condensing coil, evaporator coil and blower are all ok.

4. If the system report is outside an acceptable range of operation … you know there is a problem that needs fixed … and you can spend your time making real money by identifying real problems, making real repairs and getting paid real money … NOT CHASING GHOSTS.

You can’t make money on what you don’t fix and  you can’t fix what you can’t find!