Free HVAC Diagnostic Checklist Template

No. It is a rule of thumb that ignores the single biggest variable. The dry-bulb split across an evaporator depends on the water vapour content of the air entering it: on a humid return the coil spends much of its capacity on latent removal — condensing moisture — and drops the temperature less, so a healthy system reads a narrower split. On a dry return the same system reads wider. Work the two cases on a psychrometric chart and you get different answers from identical equipment, which is why no manufacturer publishes a single number. This form computes your split, tells you what your return wet bulb implies about it, and refuses to pass or fail it. If you want an airflow verdict, take static pressure against the equipment’s rated ESP — that one is a real comparison against a real number.

Whichever one the metering device is not controlling. A fixed orifice (piston or cap tube) cannot regulate anything, so superheat at the compressor inlet is a direct readout of charge, and the target comes off the charging chart against indoor wet bulb and outdoor dry bulb. A TXV or EEV actively modulates to hold superheat at its own setting, so on those systems superheat describes the valve and subcooling against the manufacturer’s figure describes the charge. Getting this backwards is how a working TXV holding a normal superheat gets diagnosed as an undercharge. This builder asks for the metering device first and grades accordingly.

Whatever the nameplate or the charging chart for that unit says. You will see 8 to 12 degrees quoted everywhere and it is a fair description of what a lot of residential equipment specifies — but it is manufacturer data, not a standard, and units specifying well outside that range exist. This form asks for the figure off the unit and grades your reading against that. Enter nothing and it records your subcooling and says plainly that it has nothing to judge it against, rather than inventing a target and failing a correctly charged system.

That the blower cannot move its rated airflow against the resistance in front of it — and on its own, nothing more specific. The useful move is to split the reading. High on the return side means the filter, the return grille or the return ductwork; high on the supply side means the coil or the supply trunk. Compare it to the equipment’s rated external static, not to a rule of thumb: 0.5 inches water column is typical of PSC equipment and ACCA Manual D designs to the rated figure, but ECM equipment is commonly rated higher, so a unit rated 0.8 running at 0.7 is fine and a form that fails it at 0.5 is wrong.

Possibly, but restricted evaporator airflow produces exactly the same pair of readings, and recovering refrigerant off an airflow problem leaves you worse than you started. That is why this form asks for static pressure and flags the pattern with a caveat when the air side is high or has not been measured at all. Check the filter, blower wheel and the entering face of the evaporator coil before you touch the charge. The four patterns worth memorising: high superheat with low subcooling is an undercharge, low with high is an overcharge or low airflow, high with high is a restriction between the condenser and the evaporator, and low with low is a compressor that has stopped pumping.

No, and this is one of the most common misreadings in the trade. RLA stands for Rated Load Amps, but it is not the current the compressor is expected to draw — it is a listing figure, back-calculated from the maximum continuous current the internal overload will tolerate, divided by roughly 1.44 to 1.56 depending on the manufacturer. A healthy compressor normally runs well below it. This form flags an over-RLA reading, because that means the overload is heading for a trip, and it never treats a low reading as a fault.

It depends on the refrigerant, and this is where most templates go wrong — they print one universal number. There are two rules and they run in parallel. An ozone-depleting refrigerant such as R-22 falls under 40 CFR 82.157, which still exists and still uses a 50-pound full charge; EPA's 2020 rule rescinded only the 2016 extension of those provisions to non-ODS substitutes, not the section itself. An HFC or regulated substitute falls under 40 CFR 84.106, created by the AIM Act Emissions Reduction and Reclamation rule, at 15 pounds or more with compliance from 1 January 2026. EPA describes part 84 subpart C as applying more broadly, to refrigerants that were not regulated under part 82 and to appliances with smaller charges — broader coverage alongside the older rule, not a replacement of it. The practical consequence: a 20-pound R-22 machine is under neither rule, because 84.106 does not reach R-22 and 82.157 needs 50 pounds. Telling that customer they have a leak repair obligation invents one. Above whichever threshold applies, a comfort cooling appliance leaking more than 10 percent annually must be repaired and the repair verified within 30 days, or a retrofit or retirement plan started. A typical residential split system sits under both. What is never outside it is the venting prohibition — knowingly releasing refrigerant while servicing an appliance is prohibited under 40 CFR 82.154(a) at any charge size.

Those document a system that is working. This one isolates a fault on a system that is not. A start-up report proves you commissioned new equipment correctly; a maintenance checklist proves you serviced it on schedule. A diagnostic checklist starts from a customer complaint and works backwards through readings until the cause is named — which is why this form opens with the complaint, scopes its checks to that complaint, and ends with a root-cause box tied to the readings above it.

No. It is the technician’s record of a diagnostic visit — the complaint, the readings, and the conclusion drawn from them — and every export says so. The code and regulation references appear to explain why something was checked or what obligation attaches to it, not to certify anything. Approval of any work rests with the authority having jurisdiction.