Are you having problems with your AC not blowing air inside when the AC fan and the outside condenser units are running? This is a great troubleshooting guide for you. In this guide, we are going to be looking at the 3 main scenarios your ac won’t blow air inside and the possible solutions for each of them.
Scenario 1. AC Condenser unit running but no air blowing inside at all
|POSSIBLE CAUSE||MAIN FIX|
|Tripped Breaker for air handler||Reset circuit breaker|
|Outdoor unit not connected indoor unit||Make sure the two are connected|
|Defective blower motor||Replace blower motor|
|Overheating motor||Check filter/replace it if necessary|
|Defective fan Relay||Replace fan relay|
|Defector blower motor capacitor||Replace capacitor|
|Defective circuit control Board||Replace circuit control board.|
|Leaky or broken Duct work||Seal off or mend duct work|
|Blocked Return air vents/ Registers||Remove objects from return vents|
1) Tripped Breaker for air handler
If your outside AC unit is running but there is no air blowing out of vents inside, you might want to check for a tripped circuit breaker.
In the circuit breaker box, there can be two circuit breaker switches for your HVAC system to check if there is a tripped breaker labeled air handler. If it’s tripped, reset it and turn on your air conditioner.
If you can feel air blowing out of vents, you have resolved the problem, if not, proceed to the next stage of our troubleshooting guide.
2) Outdoor unit not connected to power
Under normal operations when the outdoor condenser unit turns on , in a few minutes it will start the indoor unit fan too. But when the two are not connected things might now work the way they ought.
You should also make sure that the air handler has a power supply. Check if the switch is on and if it’s off, turn it back on.
Read also: AC condenser unit blowing cold air outside
3) Defective blower motor
The blower fan circulates the conditioned air( cool or warm) throughout the ductwork to the intended rooms.
If this component is defective, it will not blow air through the ductwork to the intended rooms and that’s probably why you have no air blowing inside.
To test whether or not the blower motor is defective or not, remove the leads from the control board to the motor, and apply 110 volt leads to the black and one other color wire.
If the motor doesn’t run, you may have a defective motor or (capacitor relay and the starter relay.)
4) Overheating motor
A motor has overheating sensors that turn it off when they sense overheating. Overheating of your blower motor can be caused by dirty air filters.
When you have dirty air filters, the motor will work hard to pull the air through and this overworking will cause it to overheat.
To resolve this issue, check the air filter typically located in the air handler. If filters are clogged, replace them and try starting your air conditioner.
5) Defective fan Relay
A relay sends power from the capacitor to the blower motor for it to run. In short, it transports power from the capacitor to the motor. When it is defective, that circuit will not complete and this will prevent the fan from starting. Relays are also replaceable if defective.
6) Defective blower motor capacitor
A capacitor supplies the needed power to start the blower motor. When it is defective, the blower motor will not run and no air will be blown into your home.
Usually when there is a defective motor capacitor, you can hear a humming sound, which comes from a motor trying to access starting power from a capacitor that is non operational.
If you are a DIY you can use a multimeter to test the capacitor for continuity. Depending on the results you might need to replace the capacitor. Capacitors are not expensive; you can get one for as low as $14 dollars online.
7) Defective circuit control Board
Does the fan run when switched to fan on mode on the thermostat? If yes,
It’s likely there is a problem with the circuit control board. The circuit control board is like the central processing unit for the AC. It coordinates all components of the HVAC system.
Many times if there are problems the control board is aware of, it will blink lights to tell you about a specific issue. If there is a window on the air handler, look into it with the system running. count the flashes for a pattern.
Then remove the door after turning off the power and compare the flashes with the list. Otherwise if the circuit control board is defective,it’ll need a replacement in which case I encourage you to hire a professional.
Also read: Furnace Running But Not Blowing Air [Fixed]
8) Leaky or broken Duct work
Over time, ductwork can become prone to wear and tear and when this happens, it can negatively affect how your air conditioner works.
And if you have a flex duct it might have an internal collapse and air flow could be blocked.
When your ductwork is leaky or broken, it will allow air to escape into the open spaces and that can prevent the air from reaching the intended rooms.
To fix the issues try inspecting the ductwork in the uninsulated spaces such as the attic and the crawl space for leaks or damage to the ductwork. If you find leaks, sealing them off should fix the problem. But the job can best be done by professionals.
9) Blocked Return air vents/ Registers
Another possible reason why no air is blowing out of the vents when your outdoor condenser is running outside is that you have locked vents or registers.
You might have closed the vents on a chilly day and forgotten to close them, or there could be something blocking the vents such as furniture and rags.
This can affect the airflow of your HVAC system, leaving you feeling stuffy and uncomfortable during hot weather.
Fortunately, this problem is easy to fix. Simply inspect all of the vents in your house and open those that are closed, or remove any obstructions that are blocking the airflow.
Scenario 2. AC fan spinning but no air blowing inside
|POSSIBLE CAUSE||MAIN FIX|
|Blocked Registers||Open/ unlock vents|
|Collapsed flex duct work||Fix duct work|
|Broken Duct work||Mend/ Seal off ductwork|
1) Blocked/closed registers
If you AC fan is spinning but you have no air blowing inside you could have blocked registers. Check the vents in the rooms and if there are objects blocking the vents, that may be preventing them from blowing air.
2) Collapsed flex duct
Another possible reason you have no air blowing from vents when your ac fan is spinning is that you have a collapsed flex ductwork. Take time to inspect ductwork and fix the ductwork where it has collapsed.
3) Leaky Ductwork
Other times it’s the leaky ductwork that could be causing the problem. As I said earlier, over time ductwork can become weak. While this is an unlikely cause, take time to inspect the ductwork for any possible leaks.
Scenario 3. AC condenser unit running but no cold air blowing inside
|POSSIBLE CAUSE||MAIN FIXES|
|Blocked AC condenser||Remove objects from condenser unit|
|Thermostat settings||Adjust thermostat appropriately|
|Dirty Air Filters||Replace dirty filters|
|Low / Leaking refrigerant||Recharge AC|
1) Blocked AC condenser
If your condenser unit is running but not lowering temperature inside, you could have a blocked condenser unit. The condenser ejects the heat from the compressor and that helps with the cooling of your indoor air.
If there are objects surrounding the condenser unit or merely shrubs surrounding it , there wouldn’t be much heat that will be disposed of and that could prevent the cooling in your home.
Ensure that you clean the condenser coils coils, if possible you can even use a hose for cleaning. If there are shrubs surrounding the condenser unit you can trim them to create enough clearance space from the condenser for proper air flow.
2) Thermostat settings
Another possible reason why there is no cold air blowing from vents is that your thermostat is not set to cool. You might have forgotten to set your fan to cool mode. If your thermostat is not set to cool, air could be blowing but there won’t be cooling inside.
3)Dirty Air Filters
Filters play a major role in the operation of the air conditioning unit. And because of that they need to be taken care of properly to ensure an efficient running of your AC.
If the air filter is dirty or clogged there would be restriction of air getting to the evaporator coils and that will stop cold air from blowing into your home.
The best fix to this problem is to replace a dirty or clogged air filter with a clean one. As a courtesy, always remember to replace filters on time.
4) Low/Leaking refrigerant
Another reason your outside ac unit would be running without cold air blowing inside is a low charge on your AC system. The refrigerant(AKA freon) is a chemical that is used in air conditioning systems to cool or heat your home by the process of evaporation and condensation.
When it is leaking and there is little of it left then you wont have cooling in your home even if you set your thermostat to ‘cool.’
It’s very hard to diagnose a leaking refrigerant from an AC system so I would recommend that you hire someone for this job unless you really know what you are doing.
In a nutshell, there could be several issues that could be preventing the AC from blowing inside when the condenser is running outside or when the AC fan is spinning.
However, all the issues that we have seen in this guide are the most common ones.
If you can fix the problems after trying out tips given in this guide, we strongly believe that you call a local licensed professional for help.
To prevent future problems with your air conditioning system, we encourage you to observe annual tune ups to ensure that you remain in great working condition all the time. Annual tune ups prevent unforeseen breakdowns of HVAC systems which can really be costly.