San Diego heat wave: keeping your AC running, and what to do if it quits

But San Diego has had record heat waves, and when one arrives, an air conditioner that has idled for months is asked to run all day. This guide is about getting through a San Diego heat wave at home: how to keep the AC working, what to check if it stops, and where to go if the house gets too hot.

Air Conditioning Repair San Diego is an independent referral service, not an air conditioning or HVAC company. Calls and form requests are passed to an independent local AC and HVAC contractor, who can contact you about your system; that contractor gives any quote and does any work.

How hot San Diego gets

NOAA’s 1991 to 2020 normals for San Diego Lindbergh Field, on the bay, give the average high as 75.3 F in July, 77.3 F in August and 77.2 F in September, with almost no rain in August. Those are averages at the coast. Inland neighborhoods and East County often run warmer, and a heat wave can push temperatures well above normal. The warmest stretch of the year at the coast is late summer, so that is when AC problems tend to show up.

Before the heat arrives

The steps that keep an AC working through a heat wave are mostly done before it starts:

• Book the check-up early. ENERGY STAR recommends a contractor check the cooling system in the spring. A clean coil, a clear drain and tested electrical parts are what a system needs to run long hours.
• Check the filter. ENERGY STAR says to inspect, clean or change it once a month; a dirty filter can damage the equipment, leading to early failure.
• Clear the outdoor unit. Move plants, boxes and furniture back so air can flow through it.
• Test it. Run the AC on a warm day before the heat wave, so you find a problem while there is time to fix it.

During the heat wave

Keep the thermostat at a steady setting rather than switching the system on and off. Keep doors and windows closed while the AC runs. Check the filter again if the system has been running long hours, and look at the indoor unit for water from the condensate drain. If the air from the vents is getting warmer, or the system is running without ever catching up, it is worth getting it looked at before it stops altogether.

If the AC quits

1. Check the thermostat: set to cool, below the room temperature, with fresh batteries.
2. Check the electrical panel for a tripped breaker. Reset it once; if it trips again, leave it off.
3. Check the filter, and replace it if it is clogged.
4. Look for ice on the lines or the indoor coil. If you see it, switch the cooling off and let it thaw.
5. Check the outdoor unit is clear and its fan turns when the system calls for cooling.

If none of that brings it back, call the number on this page or send the form. More detail is in AC not cooling? What to check first. Do not open the sealed system or add refrigerant: under EPA Section 608 that work is for technicians certified to do it.

After the heat wave

A heat wave is a hard test, and a system that limped through it may have a part that is close to failing. Have it checked. If repairs keep coming, the AC replacement guide sets out the questions to ask. If the home has no AC and the heat wave made the case for it, see AC installation or mini split installation. This site is about home air conditioning. For a car’s AC, an auto repair shop is the place to ask.

Questions people ask