April 20, 2023

Heating & Cooling Combined Unit: Why isn’t my air conditioner cooling?

When your central air conditioner runs but doesn’t cool, the problem could be caused by something as simple as bad thermostat settings. If the thermostat is set to run the fan constantly but the temperature setting isn’t low enough to initiate cooling, then you can fix the cooling problem by adjusting the thermostat settings. If the thermostat is faulty and won’t signal the air conditioner to start cooling, then you’ll need to replace the thermostat.

If thermostat settings are okay, then the outside compressor and condenser unit may not be working. Check to see if the condenser fan and compressor are running. If not, check the house circuit breakers for the outside unit. Resetting the house circuit breaker may restore cooling. A bad capacitor can prevent the compressor and condenser fan from running. Many AC systems use 1 dual capacitor to help start the compressor and condenser fan. If the capacitor is bad, you’ll need to have it replaced.

If the compressor and condenser fan both run, then lack of refrigerant or a bad compressor may be preventing the air conditioner from cooling.

Several other problems such as a wiring failure or a bad compressor fan motor can prevent the AC from cooling. If you’re not able to diagnose and fix a cooling failure yourself, have a service technician repair your air conditioner.

heating & cooling combined unit

THESE REPAIRS MAY HELP SOLVE YOUR HEATING & COOLING COMBINED UNIT PROBLEM

Thermostat replacement

Replace the HVAC system thermostat

The thermostat controls the heating and cooling system in your home. The thermostat senses the temperature inside your home and cycles the system on and off to maintain the set temperature. When your HVAC system control thermostat quits working, replace the thermostat.

Hvac system thermostat

Find the required part specific to your product.

HVAC Thermostat
March 03, 2022

How to replace a heating and air conditioning system thermostat

If the buttons on your HVAC system control thermostat don't work or if the display panel doesn't light up, the thermostat may need to be replaced. This DIY repair guide explains how to replace a thermostat in less than 30 minutes.

Repair difficulty
Time required
 30 minutes or less
Air conditioner dual capacitor

Replace the compressor/condenser fan capacitor

When the central AC circulation fan inside your home runs but the system won’t cool, the dual capacitor that helps the compressor and the condenser fan start may have failed. You may hear a buzz coming from the outside unit when the dual capacitor is bad. This typically indicates the compressor and condenser fan are getting power but the failed capacitor isn’t helping the motors start.

You’ll need to have a service technician replace the capacitor when it goes bad. The capacitor can retain an electrical charge even after you disconnect electrical power from the outside unit. The technician will short an insulated screwdriver across the capacitor leads to dissipate any stored electrical charge before replacing the capacitor. The technician will also check for additional problems that could be preventing the air conditioner from cooling.

Compressor/condenser fan capacitor

Find the required part specific to your product.

Most common symptoms to help you fix your heating & cooling combined units

Choose a symptom to see related heating and air conditioning system repairs.

Thermostat problem, clogged air filter, burner failure…

Dirty air filter, clogged condenser coils, low refrigerant charge, faulty compressor…

Thermostat problems, bad compressor/condenser fan capacitor, lack of refrigerant, failed compressor…

Main causes: errant thermostat settings, lack of electrical power, clogged drain line, wiring failure, control failure.…

Main causes: Errant thermostat settings, lack of power, bad interlock switches, lack of exhaust ventilation, wiring fail…

Dirty flame sensor, failed flame sensor, damaged burner, bad high limit switch…

Most common repair guides to help fix your heating & cooling combined units

These step-by-step repair guides will help you safely fix what’s broken on your HVAC system.

How to unclog the air conditioner drain line

How to unclog the air conditioner drain line

The condensate drain line for your central air conditioner can clog with mold and mildew. Water will back up and start d…

Repair difficulty
Time required
 15 minutes or less
How to replace the furnace flame sensor

How to replace the furnace flame sensor

The flame sensor detects when furnace burner flames are lit. You may need to replace the flame sensor if flames only sta…

Repair difficulty
Time required
 15 minutes or less
How to replace a heating and air conditioning system thermostat

How to replace a heating and air conditioning system thermostat

The control thermostat for your HVAC system can stop working. This repair guide shows how to replace it.…

Repair difficulty
Time required
 30 minutes or less

Effective articles & videos to help repair your heating & cooling combined units

Use the advice and tips in these articles and videos to get the most out of your HVAC system.

Maintaining your air conditioner

Maintaining your air conditioner

Learn how to maintain your central air conditioner to keep it running smoothly all summer long.…

How to prevent the 2 most common AC failures from ruining your summer

How to prevent the 2 most common AC failures from ruining your summer

Get tips to help keep your central AC running all summer long…

Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…