How Much Does AC Repair Cost in Houston? (2026 Price Guide)
A breakdown of what Houston homeowners typically pay for common AC repairs in 2026, from simple capacitor swaps to full compressor replacements.
Read more →Why Won't My AC's Outdoor Unit Turn On?
Serving homeowners in The Heights and nearby Houston neighborhoods.
If your AC's outdoor condenser unit will not turn on, but your indoor fan is still blowing air, the most likely causes are a tripped breaker or blown fuse dedicated to the outdoor unit, a failed capacitor, a bad contactor, a faulty thermostat signal, or in more serious cases, a failing compressor. Because the indoor blower and outdoor condenser often run on separate circuits and components, it is common for one to keep working while the other fails completely, which is exactly why this is such a common troubleshooting scenario for Houston homeowners.
Why This Happens: Indoor and Outdoor Units Work Separately
Your AC system has two main working halves: the indoor air handler or furnace with its blower fan, and the outdoor unit containing the compressor and condenser fan. They are connected electrically and by refrigerant lines, but each has its own components that can fail independently. When the outdoor unit does not respond at all, even though your thermostat is calling for cooling and the indoor fan is running, the problem is almost always isolated to the outdoor unit's power supply or starting components.
Most Common Causes
- Tripped breaker or blown fuse: The outdoor unit typically has its own dedicated breaker in your electrical panel, and sometimes a fuse in a disconnect box mounted near the unit itself. Either one failing cuts all power to the outdoor equipment.
- Failed capacitor: The run or start capacitor gives the compressor and outdoor fan motor the initial power surge they need to start turning. A failed capacitor often means you will hear a faint hum but see nothing move, or hear and see nothing at all.
- Bad contactor: The contactor is an electrically controlled switch that sends power to the compressor and outdoor fan when your thermostat calls for cooling. A worn or pitted contactor can fail to close properly, leaving the outdoor unit with no power even though everything else in the system seems fine.
- Thermostat or low-voltage wiring issue: If the outdoor unit is not receiving the low-voltage signal from your thermostat at all, it has no reason to start, even though power to the unit itself is fine.
- Failing compressor: Less commonly, but more seriously, the compressor itself can fail internally, which sometimes trips a breaker repeatedly or causes the unit to hum without starting.
- Disconnect switch left off: Outdoor units have a manual disconnect box nearby, and sometimes this gets accidentally switched off during yard work or a previous service visit.
What You Can Safely Check
Confirm the breaker for the outdoor unit has not tripped in your electrical panel. Check the outdoor disconnect box, usually mounted on the wall near the unit, to make sure the pull-out switch or breaker inside is in the "on" position. Beyond these two checks, most causes involve electrical components that carry real risk if handled without proper training, so it is best to stop there and call a technician rather than opening the unit's electrical panel yourself.
What a Technician Will Check
Electrical Testing
A technician will use a multimeter to test voltage at the disconnect, check the capacitor's microfarad rating against its specification, and inspect the contactor for pitting or failure to close.
Thermostat Signal Verification
They can confirm whether the outdoor unit is even receiving a call for cooling from your thermostat, which helps rule in or out a wiring or control board issue.
Compressor Assessment
If the simpler components test fine, a technician can assess the compressor itself using amperage readings and resistance testing to determine whether it is the underlying cause.
Why This Is Urgent in Houston
With an outdoor unit down, your home has no cooling capacity at all, and in Houston's summer heat that can turn into an uncomfortable and potentially unsafe situation within hours, especially for households with young children, elderly family members, or pets. If your outdoor AC unit will not start, do not wait to have it checked. We offer free quotes and same-day, 24/7 emergency service across the Houston area to diagnose the cause and get your cooling back up and running as quickly as possible.
Avoiding a Repeat Failure
Once your outdoor unit is running again, ask your technician what caused the failure and whether it points to a broader maintenance need. Capacitors, for example, tend to weaken gradually before failing outright, and a technician can often spot a weak capacitor during a routine maintenance visit before it leaves you without cooling on a hot afternoon. Keeping the area around your outdoor unit clear of shrubs, mulch, and debris also reduces strain on the fan motor and helps the whole outdoor unit run cooler and more reliably through a long Houston cooling season.
Need AC repair and HVAC service in The Heights? Get a free quote or call (713) 999-0113 — 24/7.
Frequently Asked Questions
Why does my indoor fan run but nothing happens outside?
This is a classic sign the outdoor unit is not receiving power or cannot start, usually due to a tripped breaker, a blown fuse, a failed capacitor, or a bad contactor. The indoor blower and outdoor condenser run on largely separate circuits, so one can keep working while the other fails entirely.
Can I test my own capacitor or contactor?
Testing a capacitor requires a multimeter and knowledge of safe discharge procedures, since capacitors store electrical charge even after power is off. Unless you have HVAC electrical experience, it is safer to have a licensed technician test and replace these parts.
How quickly can a technician fix an outdoor unit that will not start?
Many common causes, like a failed capacitor or contactor, are same-day fixes once diagnosed correctly, since these are relatively small, commonly stocked parts. More involved issues, like a failing compressor, may take longer to resolve depending on parts availability.