Tag: data

This article is part 5 of a 5 part series on troubleshooting by Senior Refrigeration and HVAC tech Jeremy Smith

This might be the most challenging part of troubleshooting. We’ve got a “Most Likely candidate” for the trouble, but we don’t know for certain that’s what is wrong.


So, we have to combine our customer skills, our experience, and our troubleshooting skills.
Let’s correct that “Most likely” problem that we’ve identified. Clean a dirty evaporator or
condenser coil, replace the plugged filter drier, repair the leak and recharge the unit to

You’re done, right?

Not so fast…

This is where things can get interesting. Looking at our flowchart, we’ve got a decision loop
here. Make the repair or correction to system operation, then reevaluate system performance. In
reality, this puts us back to the gathering data phase of the process, but we don’t have to
Necessarily gather the same data twice. If we replaced an air filter or a belt or we cleaned a
coil or replaced a capacitor, we can ignore that on our second (and maybe
subsequent) evaluations.

We’re now looking at system performance. Most manufacturers publish methods to evaluate
their systems. If those fail, we can always resort back to the ‘rules of thumb’ and check to see if
our system operations data now falls into line with accepted industry norms.
If the unit doesn’t match up with manufacturers specifications or industry standards after making
the initial repair, continue the data gathering, data evaluation and repairing the next most likely
problem the data points to.

Be very careful here not to focus on a single aspect of the system. Let’s say you had a high-pressure
trip due to a dirty condenser. So, you clean that coil and reset the pressure switch.
Don’t key in exclusively on the high side readings and miss a low superheat issue. Monitor
ALL of the system conditions and only when everything is within industry norms (or the
customer refuses the work, of course) do you move to the final part of the flowchart and
terminate the troubleshooting process.


Now go out and fix some stuff right the first time.

— Jeremy

This article is part 4 of a 5 part series on troubleshooting by Senior Refrigeration and HVAC tech Jeremy Smith

Ok, so we’ve got our data scribbled and scratched out on paper. Maybe a bit of grease, dirt and oil, too, if you’re doing things right and blood if you’re doing it wrong.


Now, time to take a short break and congratulate ourselves on doing it right while sitting and thinking. Have a coffee and look over your data. Now you have some decisions to make.


Much has already been published on analyzing data on a refrigeration system, so I don’t think I need to reinvent the wheel here and review various combinations of pressures, superheat and subcooling and airflows. If you haven’t yet internalized this information, don’t be afraid to have a nice laminated copy of the printout on your truck until you do.


The thing to remember here is that the more data you have and the more accurate that data is, the easier troubleshooting will be for you.


As an example, if you’ve got a unit with a TEV running a 10° subcooling and your low side shows a lower than expected suction pressure and superheat, do you have an airflow problem, a low load problem or a sizing issue? Without collecting good data, it can be difficult to distinguish between the problems but, if you’ve taken TESP readings, return and supply dry and wet bulb temps and have the unit model/serial info on hand when you sit down to analyze the data, the problem should be more apparent.


Evaluate the patterns in the data. Look broadly at all the data and see the patterns. If you have a good data set and a good understanding of the operation of this equipment, a “Most Likely” candidate for the problem is going to emerge.

The final step is coming tomorrow.

— Jeremy

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