Real HVAC diagnosis lives inside a handful of measurements — and a handful of things you can see, hear, and feel. Answer what you can. When something goes red, that's the conversation to have — bring your results to a Yogi Lab call and we'll walk through them together.
⚠ Smell gas or a CO alarm going off? Leave the house now and call 911 and the gas company from outside — don't use this tool.
What you can gather without instruments
Most of the diagnosis lives here. If your contractor didn't write anything down, this is what you'd bring to a Yogi Lab call.
Tier A · Phone camera
Zero tools — 5 minutes
Nameplate photos: outdoor unit, air handler, furnace
Filter frame photo (size + MERV printed on side)
Thermostat brand + current screen
Photo of any visible ice on outdoor lineset
Photo of the utility bill trend
Tier B · Fingers + eyes
Feel + look — 10 minutes
Which rooms feel hot / cold vs others
Paper test: register push (weak, medium, strong)
Sound at startup: buzz? hiss? squeal? clunk?
Filter last changed: month or "don't remember"
Outdoor unit: debris, shade, clearance
Tier C · Under $30
Cheap instruments
$20 IR thermometer: measure supply and return temp, get ΔT
A 30-minute Yogi Lab call — bring your notes here, get sourced answers.
Copy your dashboard summary above, book the call, and Yogi walks through what's missing on your contractor's quote or your own observations. If the paid on-site forensic visit is the right next step, we schedule it on the same call.