Heating & Cooling Combined Unit: Why is my furnace not blowing hot enough?

Check the thermostat settings. If the furnace is fan is set to run constantly but the temperature setting isn’t set high enough to call for enough heat, adjust the thermostat. If the thermostat isn’t working properly, replace it.

If the thermostat is set properly and working as it should, check the air furnace air filter. A dirty filter will block air flow through the heat exchanger and air vents in your home. Replace the air filter if it’s dirty.

If these tips don’t help, then a problem with the furnace burners or the blower fan could be causing the heating problems. Have a service technician examine and repair the furnace if you’re not able to restore proper heating.

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 3, 2022By Lyle Weischwill

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
Replace the furnace air filter

Replace the furnace air filter

Replacing the furnace air filter regularly to keep your furnace heating efficiently.

A dirty air filter inhibits air flow through the furnace heat exchanger and your home’s air vents. If your furnace isn’t heating as it should, check the air filter and replace it if it’s dirty.

To replace the air filter, shut off the furnace and allow the blower fan to stop if it’s running. Open the filter access door and pull the old air filter out. Position the new air filter according to the air flow arrow on the side of the filter and slide the new air filter into the filter housing. Close the filter access door. Turn the furnace back on to restore heating.

Furnace air filter

Find the required part specific to your product.

Symptoms common to all heating & cooling combined units

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

Dirty air filter, clogged condenser coils, low refrigerant charge, faulty compressor
Thermostat problem, clogged air filter, burner failure
Dirty flame sensor, failed flame sensor, damaged burner, bad high limit switch
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 failures.

Repair guides common to all heating & cooling combined units

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

March 16, 2022
By Sears PartsDirect staff
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 dripping below the inside air conditioner unit. Follow the steps in this guide to unclog the drain pipe.

Repair difficulty
Time required
 15 minutes or less
March 16, 2022
By Sears PartsDirect staff
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 stay on for a few seconds.

Repair difficulty
Time required
 15 minutes or less
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

Articles and videos common to all heating & cooling combined units

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

February 22, 2022

Why is my furnace not igniting?

By Lyle Weischwill

Find out why the burner on your furnace isn't igniting.

February 22, 2022

Can a furnace be repaired?

By Lyle Weischwill

Learn about furnace repairs and how much they cost.

February 23, 2016

What to check if your air conditioner isn't cooling video

By Sears PartsDirect staff

If your central air conditioner isn't cooling as it should, we'll show you how to check for a tripped float switch and clogs in the drain pipe.