The Problem
Possible Reasons
What You Can Do
The unit won't come on.
The thermostat is set incorrectly.
Check that thermostat is set to “HEATING” or “COOLING” and that the temperature is set for the unit to come on.
The thermostat is in the time delay mode.
Wait 5 minutes for the thermostat to complete the time delay.
The circuit breaker is tripped.
Check the circuit breaker.
The reset button has tripped.
On some outdoor units, there is a red reset button on the outside of the unit. Press it to
reset the system.
The fuse is blown.
Check the fuses in the disconnect or have them checked at a hardware store.
Furnace is unplugged.
Plug furnace in.
Many furnaces have a safety switch on the blower panel. The panel must be installed properly for the unit to operate.
Replace panel properly.
The indoor fan won’t shut off.
Thermostat fan switch is set to “ON” instead of “AUTO”
Change the setting on the fan switch.
The outdoor unit is running but there is no air blowing out of the registers.
The coil may be iced up.
Turn off the system for a few hours to allow it to defrost. Then turn it on again. While it is off, check the filter. If
it is dirty replace it or clean it.
Water leaks on the ceiling, floor or walls.
The drain pipe or hose may be clogged.
Make sure the pipe is opened at the termination point.
The air conditioner doesn’t get cool enough.
The air conditioner doesn’t get cool enough.
Turn off power to the outdoor and clean the coil with a garden hose. Clean leaves and other debris from the coil.
The return grill is blocked.
Move furniture and other obstructions away from the return grill opening.
The registers are dirty.
Clean the registers.
The registers are closed off partially or fully.
Open the registers.
Window or door to the outside may be opened for long lengths of time.
Be sure the windows and doors stay closed when
possible.
The insulation may be less than adiquate or missing above the ceiling.
If possible, inspect the attic insulation level
and add more if needed.
The rooms are not warm enough or cool enough.
The filter is dirty.
Replace the filter with the same size or clean it if is cleanable.
The return grill is blocked.
Move furniture and other obstructions away from the return grill opening.
The registers are dirty.
Clean the registers.
The registers are closed off partially or fully.
Open the registers.
Window or door to the outside may be opened for long lengths of time.
Be sure the windows and doors stay closed when
possible.
The insulation may be less than adiquate or missing above the ceiling.
If possible, inspect the attic insulation level
and add more if needed.
Unit is not blowing hot air in the heating mode.
Unit is not blowing hot air in the heating mode.
Switch to “HEAT”
Gas is not turned on.
Have gas turned on.
On gas furnaces equipped with electronic ignition, the system may have gone into safety mode.
Turn room thermostat “OFF”, allow 5 minutes to pass, then set thermostat back to “HEAT” to reset the ignition system.
Thermstat “FAN” switch is set to the “ON” position.
Switch “FAN” switch to the “AUTO” position.
Unit is not blowing cold air in the cooling mode.
The coil may be iced up.
Turn off the system for a few hours to allow it to defrost. Then turn it on again. While it is off, check the filter. If
it is dirty replace it or clean it.
There is ice on the pipes at the evaporator coil in the cooling mode.
The filter is dirty.
Replace the filter with the same size or clean it if is cleanable.
The return grill is blocked.
Move furniture and other obstructions away from the return grill opening.
The registers are dirty.
Clean the registers.
Too many supply registers are closed off.
Open the registers.
Steam or smoke is coming from the outside unit occasionally during the heating mode.
The unit may be a heat pump and is in the defrost mode. This is a normal function in order to melt the built up ice.
Steam may be produced during this cycle for 5 to 15 minutes.
Allow the unit to finish its cycle and return to the heating mode. If this takes longer than 30 minutes, turn the unit
off at the thermostat and call for service.
During the heating mode, my unit is blowing cold air for 5 to 15 minutes during the night or early morning hours.
The unit may be a heat pump and is in the defrost mode. This is a normal function in order to melt the build up of ice
on the outside coil. It will return to normal heating operation within 15 minutes.
Allow the unit to finish its cycle and return to the heating mode. If this takes longer than 30 minutes, turn the unit
off at the thermostat and call for service.
During the heating mode, my outdoor unit is leaking water onto the roof or surrounding ground area.
The unit may be a heat pump and is in the defrost mode. The water is the result of the melting ice. This is a normal
function in order to melt the built up ice on the outside coil. It will return to normal heating operation within 15
minutes.
Allow the unit to finish its cycle and return to the heating mode. If this takes longer than 30 minutes, turn the unit
off at the thermostat and call for service.
During the heating mode operation, I sometimes here a whoosh sound from the outdoor unit or when standing by the filter
grill in the house.
The unit may be a heat pump and is shifting into or out of the defrost mode.
The unit may be a heat pump and is shifting into or out of the defrost mode.
Why won’t my air conditioner turn on?
The main reasons why your air conditioner might not be turning on are:
- The circuit breaker is tripped.
- The air filter is dirty.
- The thermostat is faulty or set incorrectly.
- The AC motor is faulty.
How come my air conditioner is not cooling my home?
Some reasons why your AC may not be cooling your home include:
- There is a refrigerant leak.
- The thermostat is incorrectly set.
- The air filter is dirty.
- You have an air duct leak.
- The condenser unit is blocked.
Why won’t my AC fan turn off?
There are many reasons why your AC fan might not be turning off, but the main reason is usually because the thermostat is set to “on” instead of “auto”. If the thermostat is set to “on,” your AC fan will run continuously. Other common problems can include a dirty air filter, low refrigerant and a faulty fan limit switch.
