Is your ac compressor not working but fan is running? There are quite a few issues that could prevent your compressor from running. These issues can range from ‘easy to fix’ to more complex ones that can require a licensed Technician to come and have a look.
Some reasons your compressor is not working but your fan running include, bad compressor capacitor, bad starter relay, low refrigerant levels, power issues, bad thermostat wiring, bad contactor and a dead compressor. Shortly, we’ll be looking at these issues in little bit in details.
Air conditioners are typically installed with two fans. One fan that is installed inside your home blows air throughout your home, and the other one found in the ac condenser unit blows away heat from the coils.
Let’s now look at what can cause your compressor not to run when your fan(s) are running.
Read also: Home AC Compressor Not Turning On [Solved]
Why Is My AC Compressor Not Working but Fan Is Running?
Your AC system has two fans so, lets start by looking at what can cause your indoor fan to run when your compressor unit is not working. Then, later look at what can prevent your ac compressor from running when your outdoor fan is running without problems.
Case #1: AC Compressor Not Working but Indoor Fan is running
If you have an ac compressor that is not working but your air handler fan is running properly, look out for the following things:
1. Problems With Power
Power and electrical related issues are common causes for your ac compressor not working. When your compressor and the whole condenser unit is not turning on, this is a clear sign of a power issue. In order to troubleshoot and fix power issues, you should start by checking with the following things:
- Circuit breakers and power switches for both the outdoor unit and your indoor unit. Check the air conditioner circuit breaker and verify that it is not tripped. Reset the tripped breakers. If the breaker trips again, you definitely need to call in HVAC professionals.
- If the disconnect is pulled out. A disconnect is a small device planted on the wall of your house near the refrigerant lines. It acts as a switch to cut off power from your condenser unit for any reasons you have. A disconnect can also cut power if it’s inserted upside down or in the other way. If everything is fine with it, lets move to the next step.
2. Bad AC contactor
A defective ac contactor can be the reason your compressor is not turning on. A contactor conducts electricity to all other components of your condenser unit. It has a coil inside and can get magnetic when there is a signal to do so.
When the coil inside the contactor gets burnt out, it will not close the circuit and the condenser unit will be cut off from power. Meanwhile, your air handler inside will not be affected, and fan can be running quiet fine.
To rule out an ac contactor, get a screwdriver and manually push a metal plate against the other one to complete a circuit. If the unit starts running, then the problem is with the contactor. If it doesn’t, then something else could be messing with you. At this point, you need to look at your compressor capacitor.
3. Bad Compressor Capacitor
A compressor capacitor that is defective could be the reason your ac compressor is not turning on. A capacitor is an important part of your ac condenser unit because it powers your compressor and fan motor. Among all the top issues that can stop your compressor from running, a defective capacitor is the most common one.
The good part is compressors are usually cheap to buy and easy to fix. Just make sure before touching the capacitor, you discharge it of all voltage.
Sometimes, you can tell when a capacitor is defective if it has a swollen top but other times, there could be no signs at all. In this case you will need a multimeter to test it for continuity.
4. Bad Thermostat Wiring
A thermostat that is not properly wired can fail to make cooling calls to your HVAC system. This could be why your compressor isn’t working. Pull off your thermostat from the wall and check its wiring.
Make sure there is a jumper between R terminal(power) and the Rc terminal (power for cooling). Without Rc terminal connected, your compressor won’t turn on to start cooling.
Other thermostat issues that could affect the working of your compressor include thermostat settings. For your AC compressor to start running, your thermostat has to be adjusted to the temperature that is lower than the room temperature reading.
5. Low Refrigerant
If the refrigerant is leaking out of your ac system, the low-pressure switch will detect this and can shut off the compressor over at the contactor. The low-pressure switch ensures that there is enough refrigerant in your ac system.
6. High pressure Switch
The high-pressure switch will shut off the compressor if it detects high pressure in your system That is, if the condenser can’t eject heat for some reasons like, when its blocked or has lots of build up on it. If the fan motor is defective, much of the heat absorbed from your home won’t be ejected and the pressure is going to rise and cause high pressure switch to kick in and discontinue the pressure from rising.
Case #2: AC compressor Not Working but Outside Unit Fan is Running
Sometimes, you might notice a compressor that is not working but your condenser fan is working without issues. Most of the time, the problem is caused by a dead compressor capacitor.
A dual ac capacitor powers your compressor on one side and your fan motor on the other side. If one side that powers the compressor becomes defective, your compressor won’t work but your fan will run.
In that case you need to replace your ac capacitor. Compressor capacitors these days are readily available in the market. If you are not comfortable with doing all the stuff yourself, it’s in order to call professionals for help.
Bad Starter Relay
A starter relay works in hand with a capacitor. It transports the energy from the capacitor to your compressor. In cases where your starter relay becomes defective, it won’t send energy to the compressor to start running.
A Dead Compressor
Overtime, your ac compressor can age and pass its life span. Usually, a compressor can work for about 10-15 years. But if you have been taking care of it well, it can stay little bit much longer than that. However, when it dies, that’s it. Compressors are expensive to replace. If yours dies, consider replacing the whole system.
The general rule of thumb is, if replacing your compressor or other parts of the ac system costs more than 50% of the amount you would spend to get a new HVAC system, replace the whole system.
If you have an ac compressor not working but fan is running, try out our tips in this guide. But if you can’t figure out or solve the problem, it’s best to call in professional services.
We’d also advise you to have your air conditioning system checked and maintained regularly. You can have scheduled maintenance in the fall and spring. This will ensure your system running in the best condition and prevent unforeseen problems. Thanks for reading.