The short answer
When a Trane AC runs but won’t cool in Northern Virginia, start with three things you can check yourself: the thermostat on Cool with the fan on Auto, a clean filter, and an outdoor unit that isn’t caked with grass clippings or pollen. If the air is still warm after that, look for ice on the indoor coil or the copper lines, listen for a hiss, and check whether the outdoor fan spins. Those point to low refrigerant from a leak, a failed part, or an airflow problem, and that’s a call.
Check these first
From Trane’s own page on an AC not blowing cold air:
- The thermostat. Set to Cool, a few degrees cooler than the room, with the fan on Auto. On On, the fan keeps blowing between cycles, and that air isn’t cooled. Fresh batteries if it takes them.
- The filter. Trane says every 1 to 3 months (filter guide). A clogged one starves the coil of air (which filter to buy).
- The outdoor unit. Dirt, grass clippings and pollen build up on the coil and choke the airflow. Keep plants 2 feet back.
- The drain. Many systems have a safety switch that shuts cooling off when the drain pan backs up. Water in the pan is the sign, and the fix is a tech’s job.
Trane also warns that repairs past these checks can void the warranty if you do them yourself.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Cleaning the outdoor coil
Trane’s page on cleaning condenser coils keeps the homeowner part simple: plants trimmed 2 feet back on all sides, debris off the top, and if you want, a gentle rinse from the outside with a garden hose. No jet setting and never a power washer; the force bends the fins, and bent fins block air just like dirt does. Cleaning inside the unit is tune-up work for a tech.
If you see ice
Ice on the indoor coil or the cabinet, frost on the copper lines, or water puddling around the indoor unit means the coil froze. Trane’s page on a frozen evaporator coil says to switch the thermostat from Cool to Off and let it thaw, and never chip the ice off. The causes, from that page: a dirty filter, blocked return vents, a dirty indoor coil, low refrigerant, or a thermostat problem.
Low refrigerant means a leak
An AC doesn’t use up refrigerant. If it’s low, it leaked, or the install left it short. Trane’s refrigerant leak page lists the signs: the house feels humid, some rooms cool and others don’t, the power bill climbs, oily spots show on the lines, or you hear a hiss. A top-up runs $190 to $740; if it needs one again, the leak itself gets found and priced in writing. Newer Trane systems run R-454B (what R-454B means for you).
What the outdoor unit is telling you
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Swipe to see all columns →
| What you notice | What it usually is | Typical repair |
|---|---|---|
| Hums but won’t start | The capacitor | $240 to $370 |
| Silent while the thermostat calls for cool | The contactor | $290 to $425 |
| The fan on top won’t spin (AC fan not spinning) | The condenser fan motor or its capacitor | $1,100 to $1,500 |
| Runs, but the larger copper line isn’t cold | Low refrigerant | A top-up runs $190 to $740; the leak is priced in writing |
If it won’t start at all, that’s a different checklist: Trane AC not turning on.
If it’s a heat pump
A Trane heat pump uses the same outdoor unit to heat and cool. Trane’s page on a heat pump that won’t cool has a useful test: switch it to Heat. If it heats but won’t cool, suspect the reversing valve, and leave that one to a tech, since working on it yourself can damage the valve and cause a leak. If it does nothing in either mode, call. A tripped breaker is a call too. In winter, see Trane heat pump not heating and Trane emergency heat.
A drain that keeps clogging has its own guide (condensate drain clogs), and our AC repair page covers what we fix.
Book it
Call (703) 997-9757 or book from our AC repair page. The diagnostic is $99, and you get the problem and the price in writing before any work starts. If your Trane is a heat pump, the same outdoor unit heats the house all winter, and our heating check is $67 per system; book that one from goswiftpro.com/cookiesoffer and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why is my Trane AC running but not cooling?
Start with the thermostat on Cool and the fan on Auto, a clean filter and a clear outdoor coil. If it’s still warm, it’s often ice on the coil, low refrigerant from a leak, or a failed capacitor or fan motor.
Why is my Trane AC blowing warm air?
If the fan is set to On, it blows uncooled air between cycles, so set it to Auto. If it blows warm air while it’s cooling, check the filter and the outdoor coil, then call.
What should I do if my AC coil is frozen?
Switch the thermostat from Cool to Off and let it thaw. Don’t chip the ice. Then check the filter, since a clogged one is a common cause.
Can I hose off my Trane outdoor unit?
Yes, gently, from the outside with a garden hose, per Trane. No jet setting or power washer, which bends the fins.
How much does it cost to recharge a Trane AC?
A refrigerant top-up runs $190 to $740 in Northern Virginia. If it needs refrigerant again, there’s a leak, and finding it is priced in writing.
The system we put in first
Built to take a beating. Put in by our crew.
Heat lamps, snow and rain on one outdoor unit: that’s Trane’s own film. We’re a Trane Comfort Specialist, on Trane’s own dealer locator, and when you pick a Trane, our crew puts it in.
Films: Trane’s own.
