Air Conditioner Repair Checklist
1. AC Won’t Turn On
There can be several explanations why your AC unit won’t start: a tripped circuit breaker, incorrect thermostat settings, a shut off switch or a full condensate drain pan.

Overloaded Circuit Breaker
Your air conditioning won’t run when you have a tripped breaker.
To find out if one has tripped, locate your house’s main electrical panel. You can spot this silver device on the wall in the basement, garage or closet.
- Ensure your hands and feet are dry before you check the panel or breakers.
- Locate the breaker marked “AC” and make sure it’s in the “on” position. If it’s triggered, the switch will be in the "off" position.
- Quickly move the switch back to the “on” position. If it instantly flips again, leave it alone and call us at 303-452-4146. A fuse that keeps flipping may indicate your home has electrical trouble.
Incorrect Thermostat Settings
If your thermostat isn’t telling your system to start, it won’t switch on.
The first part is making sure it’s set to “cool” and not “heat.” Otherwise your air conditioner might not turn on. You may also have hot air blowing from vents being the furnace is going instead.
If you rely on a regular thermostat:
- Replace the batteries if the monitor is empty. If the readout is showing jumbled letters, get a new thermostat.
- Check the proper option is displaying. If you can’t change it, override it by dropping the temperature and pushing the “hold” button. This will force your AC to work if scheduling is wrong.
- Attempt to set the thermostat 5 degrees colder than the space’s temperature. Your AC won’t cool if the thermostat is set the same as the house’s temperature.
Once your thermostat is set properly, you should receive cold air quickly.
If you’re using a smart thermostat, such as one made by Nest, Ecobee, Lux, Honeywell or Bosch, check the manufacturer’s website for troubleshooting. If it still won’t work, reach us at 303-452-4146 for support.
Shut-Down Switch
Your system typically has a shut-off device by its outdoor unit. This device is commonly in a metal box hung on your house. If your equipment has recently been repaired, the device may have inadvertently been turned off.
Blocked Condensate Drain Pan 
Condensate drain pans keep the additional water your system pulls from the air. This pan can be positioned either below or inside your furnace or air handler.
When there’s a clog or clogged drain, water can accumulate and prompt a safety feature to stop your system.
If your pan has a PVC pipe or drain, you can clear the surplus water with a custom pan-cleaning tab. You can buy these capsules at a home improvement or hardware retailer.
If your pan involves a pump, locate the float switch. If the switch is “up” and there’s water in the pan, you might have to get a new pump. Contact us at 303-452-4146 for support.
2. AC Blows Warm Air
If your AC is on but not cooling, its airflow could be obstructed. Or it might not have sufficient refrigerant.

Obstructed Airflow
Your equipment’s airflow can be restricted by a blocked air filter or dirty condenser.
How to Replace Your Air Filter
A dusty filter can cause numerous problems, like:
- Limited comfort
- Frozen refrigerant lines or evaporator coil
- Inconsistent cooling
- Larger utility costs
- Making your system break down faster
We suggest changing flat filters every four weeks, and pleated filters every three months.
If you aren’t sure when you last replaced your filter, shut off your system fully and remove the filter. You can find the filter in your furnace or air pump’s blower compartment. It may also be found in an adjoining filter case or wall-mounted return air grille.
Angle the filter up to your light fixture. If you can’t see any light, you need to buy a new filter.
4 Steps to Cleaning Your AC Unit
Weeds, grass and leaves can get in the way of your condensing equipment. This could limit its airflow, make it less energy efficient and impact your comfort. Here’s a way you can get your unit operating well again.
- Switch off electricity fully at the breaker or outdoor lever.
- Remove plant debris around the AC. Once you’ve cleared all the clutter within a two-foot space, you can use a paint brush or vacuum to gingerly remove dust from the equipment’s fins. Misshapen fins can also impact effectiveness.
- Use a hose nozzle to carefully take off dirt on the fins from inside the equipment. Don’t get liquid on the fan motor.
- Turn on the power.
Not Enough Refrigerant
When cooling units don’t have ample refrigerant, they’ll struggle to remove heat and humidity from your rooms.
Here are several flags that your unit is losing refrigerant:
- It takes a long time to cool your home and you’re continually lowering the thermostat.
- Air coming through the registers isn’t as cold as it should be.
- You’re noticing whistling or gurgling noises when the AC is on.
- Your evaporator coil is icy on account of having an issue taking on humidity.
Worried your unit is leaking refrigerant? You need a certified heating and cooling service professional to repair the leak and restore the correct level of refrigerant in your equipment. Call us at 303-452-4146 for assistance.
3. AC Not Blowing Enough Air
When it appears like you’re not receiving adequate amounts of cool air, there’s probably a clog or separation somewhere in your cooling unit.
- The initial stage is checking your air filter. Get a new one if it’s soiled.
- Make sure the vents are open throughout your residence.
- If you’re still not getting sufficient cold air, you should have your duct system inspected by a professional like Northglenn Heating & Air Conditioning, Inc.. Your duct system might need to be repaired or reconnected in limited space locations like your attic, basement or crawl space.