Troubleshooting your AC problems is not an easy task. But surprisingly there are many which you can actually take care of yourself. You need not be an engineer to get a handle on them. Instead, all you need is a helping hand in the form of a useful and informative guide. In that context, here is a little guide which will help you understand the AC contactor failure symptoms and what to do when that happens.
What Is AC Contactor?
Yes, we know you must be wondering “what on earth is an AC contactor”? A contactor is an electrical transmitter or relay in the AC. It regulates the flow of electricity to various parts. For example, the contactor sends current to the condenser as well as the outdoor fan motor. Basically, a contactor allows or prevents power to the AC unit.
In layman terms, it is an electrically controlled switch which is used for switching an electrical power circuit. Usually, a contactor is controlled by a lower power level circuit than the switched circuit. For example, a coil electromagnet of 24-volt controls a motor switch of 230-volt.
What Does The Contactor Do In AC?
In an AC the contactor closes to create an electrical circuit. This allows your AC unit to start when the thermostat sends the signal for cooling or heating. When the thermostat calls for heating or cooling, a magnetic action occurs. This forces a connection between the contactor’s volt side (line side) and the load side. The load side is one where the compressor and fan motor are coupled. When the thermostat halts calling for action, the contactor opens. When the contactor opens, it stops all power to the AC.
What Happens When The Contactor Is Faulty?
When the contactor develops a fault or goes bad, it may need replacement. In such a case, it will not pull close. When that happens, the two ends do not connect with each other even when the current is directly run to it. In case your thermostat is clicking on; however, the unit itself isn’t operating, the contactor is most likely completely gone. If that is not the case, it is not getting the much-needed electric current.
AC Contactor Failure Symptoms
There are 3 main signs which indicate a bad contactor in your AC. These are –
1. Chattering – the plunger tends to chatter when the contacts are dirty or when the coil has become weak. The chattering sound can be heard when the plunger is trying to make contact but is unable to do so completely. It fails to engage and instead produces the sound.
2. Humming – When the AC is turned on, you hear a humming sound; however, it does not power on. The humming sound is made by the coil, but the contact is still not made as the button isn’t being pulled in. Manually pushing in the button will get your AC unit functioning normally. The humming sound is also an indicator of weak coils or dirty contacts.
3. Melting – In really extreme cases, you may see that the plastic molding or the plastic casing on the contactor has melted. This too points towards the fact that the contactor needs immediate replacement.
Repairing Or Replacing A Contactor
One thing pretty evident from the above discussion is that there are 3 main reasons for the AC contactor failure. These are –
1. Dirty contacts
3.Complete breakdown or burnout.
In either of the above cases, it is possible to carry out repairs, but ideally, they are not worth the effort. It would be much better to replace the defective component. In the long run, it is a more financially feasible decision. These days replacements are readily available and that too for a fraction of the cumulative repair cost.
Dirty Contacts – On a contactor, there are points of contacts which become corroded, charred, and sometimes even dirty. These can easily be cleaned with the help of some contact cleaner. Go light on the cleaner as the points of contact are really small; there is no need to douse them in the cleaner.
Weak Coils – In case of coils repairing is not possible. They can only be replaced. Replacing just the coils in the contactor is a tedious and troublesome task. It involves taking out the contactor from the AC and then dismantling it to reach the coil. A much more feasible and quick approach is to replace the entire contactor. Residential unit contactors are relatively cheap and cost anywhere between $20 to $30.
Complete Burnout – Complete burnout means there is no life left in the component. That is why it cannot be repaired; instead, it can only be replaced.
While replacing keep in mind the specifications of the original component and replace with one which matches all those. Replacing is easy; all you need is a flathead screwdriver. Switch off the power to the AC unit. From the contactor, disconnect the wires. Remove the feet from the unit by unscrewing. Now, on the new part, screw the feet back on the unit.
Finally, reconnect the wires and the job is done. This job you should do only if you are sure that you can do it properly. Else, call an AC technician to take care of the problem for you.
Save Your AC
Had all air conditioner problem solving been easy, you would never need an AC technician or for that matter the various HVAC companies. The fact remains that your AC is a delicate piece of equipment and needs to be handled carefully. This is why it is strongly suggested that instead of taking matters in your own hands, you should let people who are trained for the job take care of them.
If however, you have the technical know-how to deal with the issues, you can save a great deal in repairing and replacement costs. Whatever you decide, always remember to switch off the power supply to the AC unit whenever carrying out any activity related to repair and maintenance. Also, have your electrical safety knowledge up to date and be extremely cautious.