Answer first, context after
What should I set the thermostat to when I travel in summer?
Set it around 85, not off. In Bakersfield heat an unconditioned house punishes everything inside it, and a system recovering from 100 degree indoor temperatures works harder and longer than one that simply held 85 all week. Off feels thrifty and usually is not.
The instinct is understandable: nobody is home, so why cool the place? But a Bakersfield house with the AC off in July is not a neutral box. It is an oven on a slow setting.
What happens inside a sealed house during a 105° week: indoor temperatures climb past 100 and stay there. Wood floors and cabinets dry and shift, electronics and batteries bake, candles slump, medications and pantry goods cook, and anything glued, from furniture joints to shoe soles, starts to let go. The refrigerator also runs continuously against a 100° kitchen, which is its own quiet abuse.
The energy math is less generous than it looks. Holding 85 is cheap because the system runs in short, easy cycles against a 20 degree gap. Recovering a 102° house back to 75 on the day you land means hours of continuous runtime through the hottest part of the day, exactly the duty cycle that kills weak capacitors. We meet a lot of failed systems on the first evening home from vacation, and it is not a coincidence.
The comfortable version of this: hold 85 while you are gone, then drop the setpoint the morning you fly home so the system recovers during the cooler hours. A smart thermostat makes that a two-tap job from the airport, and at $240 to $420 installed it tends to pay for itself in exactly these weeks.
If you are leaving for a month or more, it is worth a quick conversation before you go. Long-vacancy settings depend on the house, and the advice is free.
Still stuck? That's what the truck is for.
The diagnostic is $89, waived when you book the repair, with a written flat price before any work starts.