The Pre-Summer Walkthrough: Room by Room, Fifteen Minutes
A structured walk through your own house in April tells a technician more than any description over the phone.
A pre-summer room-by-room walkthrough checks airflow at every supply register, identifies rooms that run warm, confirms returns are unblocked, and notes any unusual sounds or smells. Documenting this in April gives a technician specific information and identifies duct problems that equipment changes will not fix.
Why doing this yourself is useful
When a homeowner says "the house does not cool well," a technician has almost nothing to work with. When a homeowner says "the two west bedrooms run four degrees warmer than the thermostat after 3pm, and the register in the back bedroom has noticeably weaker airflow than the front one," that is a diagnosis nearly formed.
The walkthrough takes fifteen minutes and it is the difference between those two conversations.
What to bring
- A cheap probe or instant-read thermometer
- A notepad or your phone
- A piece of tissue paper, for checking airflow direction at returns
Run the system for at least fifteen minutes before starting so everything has stabilized. Do it on a warm afternoon, not a mild morning — you want conditions that resemble the problem.
In each room
- Measure the room temperature at about five feet, away from windows and vents. Note it against the thermostat setting.
- Hold your hand at each supply register. Is air coming out with reasonable force? Compare rooms.
- Check the supply air temperature at the register with your thermometer.
- Look for obstructions. Furniture, rugs, curtains, boxes over registers or returns.
- Check damper position behind the register — did someone close it?
- Note the exposure. Which direction do the windows face? Is there afternoon sun?
- Listen. Whistling, roaring, or rattling at registers.
At the return grille
Hold a tissue near the return grille. It should be pulled firmly against it. Weak suction at the return is an important finding — it points to a restriction upstream or an undersized return.
Check that nothing is blocking it. A sofa pushed against a return is one of the most common and most fixable problems in a Valley home.
If your home has more than one return, check all of them, and note whether one is doing noticeably more work than another.
The system-level measurement
With the system running, measure the air temperature at the return grille and at a supply register close to the air handler. Subtract.
That temperature split should land between 16 and 22 degrees. Below 14 suggests low refrigerant charge or a weak compressor; above 24 suggests restricted airflow.
Write it down with the date and the outdoor temperature, on tape inside the air handler door. Next April you will have something to compare against.
Reading your own results
| Finding | What it points to |
|---|---|
| One room warm, weak airflow at its register | Duct problem — crushed run, disconnected boot, or damper |
| One room warm, good airflow | Load problem — west glass, insulation, or undersized supply |
| All rooms warm, weak airflow everywhere | System-wide: filter, coil, blower, or return restriction |
| All rooms warm, good airflow | Capacity or refrigerant problem |
| Upstairs warm, downstairs fine | Classic two-story distribution issue |
| Weak suction at the return | Undersized or restricted return; check for blockage |
| Whistling at a register | Too much velocity through too small an opening |
What to do with it
If everything checks out, you have a baseline and a good summer ahead. Book the maintenance visit and move on.
If you found specific problems, you now have information that makes the service call efficient. Hand the technician your notes. A room-by-room list with airflow observations and temperature readings lets them go straight to the likely cause.
And critically: act in April. Every year we take calls in July from people who noticed something in spring and hoped it would resolve. Systems do not improve on their own, and the Valley does not offer a gentle ramp into summer.
Frequently asked
How do I check if my A/C is working properly?
Run it fifteen minutes on a warm day, then measure the temperature difference between return air and a nearby supply register — it should be 16 to 22 degrees. Then walk each room checking airflow at every register and noting which rooms run warm.
Why do some rooms have less airflow than others?
Usually a duct issue: a crushed or kinked flex run, a boot that has pulled away from the ceiling, a closed damper, or a run that is simply undersized. Distance from the air handler also matters, which is why far rooms suffer first when the system is marginal.
What should I tell my HVAC technician?
Specifics. Which rooms run warm and by how much, which registers have weak airflow, what the temperature split measures, when the problem started, what the filter situation is, and any sounds or smells. That turns a vague complaint into a directed diagnosis.