Your AC filter is probably due for a change right now. Before summer heat hits the Tri-Valley, there’s a short list of things you can do yourself to cut the odds of a breakdown, and a few things that genuinely require a licensed tech. Here’s the honest breakdown.
Filter: Change It Yourself, Change It Often
This one’s fully DIY and it matters more than most people realize. A clogged filter chokes airflow, forces the blower to work harder, and can freeze up the evaporator coil. For most homes in Pleasanton, Dublin, or Livermore, a 1-inch filter every 30–60 days during cooling season is the right interval. Thicker 4-inch media filters last longer, sometimes 3–6 months, but check the manufacturer’s recommendation.
Buy the right MERV rating for your system. MERV 8–11 is the sweet spot for most residential equipment. Higher isn’t always better: a MERV 13 in a system not designed for it can restrict airflow almost as badly as a dirty filter.
Outdoor Condenser Coil: Clean It, But Carefully
The condenser (the big unit outside) works by dumping heat from your refrigerant into outdoor air. If the coil fins are packed with cottonwood, dust, or grass clippings, it can’t shed heat efficiently. Your system runs longer, works harder, and your electric bill climbs.
What you can do: turn the system off at the disconnect (the box mounted near the unit), then rinse the coil from the inside out with a garden hose. Don’t use a pressure washer — the fins are aluminum and will bend flat under that kind of pressure, killing airflow. Straighten badly bent fins with a fin comb if you can find one at the hardware store.
What you should not do: spray coil cleaner into the coil without reading whether it’s a no-rinse or rinse-required formula. If you’re not sure, plain water works fine for light surface dirt.
Give the unit at least two feet of clearance on all sides. If shrubs or a fence have grown up around it, that’s costing you efficiency.
Condensate Drain: A Small Thing That Causes Big Problems
Your air handler has a condensate drain line that removes the water the evaporator coil pulls from the air. In humid Bay Area summers, algae and mold build up in this line. When it clogs, the drain pan overflows. Some systems have a float switch that shuts the system down when the pan fills, which means no AC on the hottest day of the year.
You can flush it yourself. Find the PVC drain line coming out of your air handler, locate the access port (usually a T-shaped cap), pour about a cup of white vinegar in, let it sit 30 minutes, then flush with water. Do this once at the start of summer.
If you see standing water in the drain pan, or water stains on the ceiling below an attic air handler, the clog may already be downstream. A wet-dry vac on the drain outlet often clears it, but if water has backed up long enough to cause any damage, call someone.
Thermostat Check
Before you assume your AC is broken, run a basic sanity check on the thermostat. Set it 5 degrees below current room temperature in cool mode and confirm the system starts within a few minutes. Check that the fan runs when the system is on. If you have a smart thermostat, make sure it didn’t lose its schedule or wifi connection after a power blip.
If the thermostat screen is blank and it’s battery-powered, new batteries fix this more often than you’d think.
What Requires a Licensed Tech
Refrigerant work is the big one. Adding refrigerant, checking for leaks, or recovering refrigerant at end of life all require EPA Section 608 certification. It’s not just a formality — residential refrigerants operate at high pressure and can injure you if something goes wrong. If your system is low on refrigerant, there’s also a leak somewhere, and topping it off without finding the leak is a temporary fix that doesn’t address the root cause.
Electrical work inside the air handler or at the condenser — capacitors, contactors, control boards — is also tech territory. Capacitors hold a charge even after the unit is powered off. A failed run capacitor is one of the most common reasons a condenser motor hums but won’t start. It’s a relatively inexpensive part that takes a trained tech about 15 minutes to swap, but only after safely discharging it first. Don’t skip that step.
Evaporator coil access, blower wheel cleaning, and anything involving refrigerant line sets: leave those to a tech.
When to Call a Pro
A few specific situations where you want someone out before the problem gets worse:
- The system runs but the house won’t cool to setpoint on a day under 95°F
- Ice forming on the refrigerant lines or the outdoor unit (outside of defrost cycle on a heat pump)
- A burning or musty smell when the system starts
- The circuit breaker for the AC trips more than once
- Water in the condensate pan that won’t clear after you flush the drain line
None of these are emergencies in the sense that they’re dangerous to your family, but they tend to get more expensive the longer they sit.
What a Real Tune-Up Covers
Filters, coil rinse, and condensate drain you can handle yourself in under an hour. Refrigerant, electrical, and anything you’re not sure about — those warrant a call. A proper annual tune-up by a tech covers the things you can’t easily see: refrigerant charge, static pressure, electrical connections, and a visual on the heat exchanger if you have a gas furnace paired with the system.
If you’re in the Tri-Valley or East Bay and want someone to do the full check before summer, we do that at Adrium Service. You can book at adriumservice.com, or call if you’d rather talk through what your system needs first.