TOPIC: What is the best way to check an ac unit?

"For a more accurate reading, "


That is by no means more accurate!

i figure it's more accurate because it actually uses a probe in direct contact with what is being measured instead of a beam of light.

The issue is that you are taking about an "apparent temperature" that must be "corrected" just as with any thermal camera requires.

You can get close, but close doesn't count.

Still you are not talking the same language!

Most of these IR therm can not adjust for this, so your wrong to start!

Do yourself and everyone involved a favor and just don't go there.

okay, so as far as reporting on the system, an inspector shouldn't really take measurements, but just kind of stick to the book, looking for obvious defects like flame rollout or cracked exchanger, and maybe the condition appearance of the ac compressor? We sure don't need to open ourselves up to more liability by reporting on or about something we are not trained or qualified to report on or about, like temp differentials.

David,

Is there a way for a HI to test a unit and be confident in saying have the system evaluated or it seemed to be working properly...?

My goal is to protect my clients the best I can. 

Turn on the heat and watch the flame (if you can see it) when the indoor fan comes on. Changes indicate heat exchanger issues.

Turn on the A/C when you get there, after it gets to run for a while check the large refrigerant line. It should be quite cold to the touch and generally wet if exposed outdoors. If it's dry where you live, you may not get he condensate. Big line runs 50-55F.

You should not feel much heat in the small line (if hot, the coils are dirty, even if they look clean). Small line is about the same as your hand temp 95F.
Air discharging the outdoor condenser should not be more than 30F above the OA temp.

Air flow at all registers (use your hand).

This stuff only works if you are in the cooling season (+75F). If it gets cool outside, the metering device will starve the evaporator and the lines will not be the right temps.


There is no single test that says it's good or bad. There is no fuel gauge that says full or empty. Even the HVAC guys don't always get it right, thus the liability to the HI when they try to "evaluate" without the training.