AC Running But Not Cooling in Boise
The fan is going, air is moving, nothing is cold. In the Treasure Valley this is the most common summer call, and it is usually one of three parts.
In Boise, a failed run capacitor is the most common cause of an air conditioner that runs but does not cool, and replacement typically costs $160-320.
A failed contactor costs $150-300 to replace in the Treasure Valley and takes under an hour.
Low refrigerant is never normal wear - a sealed system does not consume refrigerant, so low refrigerant always means a leak, and repair runs $240-1,400.
Match the symptom to the part
| What you notice | Most likely cause | Typical Boise cost |
|---|---|---|
| Outdoor fan not spinning, humming | Run capacitor | $160-320 |
| Outdoor unit silent, indoor fan runs | Contactor or capacitor | $150-320 |
| Weak cooling, longer run times | Low refrigerant from a leak | $240-1,400 |
| Weak cooling during a smoke stretch | Filter loaded with particulate | $0-40 |
| Ice on the copper line | Airflow starvation or low refrigerant | $0-1,400 |
| Warm in some rooms only | Duct leak or blocked return | $140-750 |
Two things to check before you call
- Pull the filter and hold it up to a light. If you cannot see light through it, that is very likely your whole problem - and during a Boise smoke summer it can load in weeks rather than months.
- Look at the outdoor unit. In this valley the fins pack with dust, cottonwood fluff and agricultural chaff. With the power off at the disconnect, rinse gently with a garden hose from the inside out.
About the capacitor
The run capacitor is a small cylinder that gives the compressor and fan motor the jolt they need to start. It is a wear part and sustained heat shortens its life, which a valley summer supplies. The classic sign is an outdoor unit that hums while the fan blade sits still.
It is also, unfortunately, the part people most often get overcharged on. The component itself is cheap and the work takes under an hour, so if the number in front of you is well past $320, the reasonable question is simply: what else are you replacing while you are in there?
Common questions
Can I just top up the refrigerant each summer?
You can, but you are paying to refill a system that is leaking into the atmosphere. Locating and sealing the leak is a bigger bill once, and then the bills stop. Anyone recommending an annual top-up without ever looking for the leak is selling a subscription.
Why does my AC cool overnight but not in the afternoon?
That pattern points to a marginal system rather than a broken one - low refrigerant, a dirty condenser, or capacity that no longer matches the load. Boise's big day-night swing masks it until the afternoon peak.
Is a hard-start kit worth it?
On an older compressor struggling to start it can buy time for around $120-240. It is a stopgap, not a repair, and an honest technician will say which one you are buying.