Air conditioners have come a long way from the first Carrier units. There are now different types of AC units, most of which have thermostats that help control the cooling system. The thermostat is a convenient component of any heating and cooling system as it allows the homeowner to adjust the furnace or air conditioner settings to their preferences.

An HVAC system may have a smart thermostat that regulates the temperature of the unit based on the weather, or a programmable thermostat that allows customization of the furnace and air conditioner. However, if the thermostat is faulty, then it can be a hassle to operate the unit as the component may cause the AC to go haywire.

Diagnosing a Faulty Thermostat

Faulty thermostats can cause a multitude of problems, especially as it is the control panel of the AC unit. A faulty thermostat can cause the temperature to fluctuate, or cause the unit to short cycle as it turns the unit on and off. Here's how to diagnose a faulty thermostat:

#1 Malfunctioning Unit

A faulty thermostat will cause the unit to malfunction. More often than not, you may notice fluctuations in the temperature of the HVAC system, or a spike in cooling bills. The air conditioning unit may shut off unexpectedly, or operate at different temperatures, fan speeds, or modes than what you've programmed.

#2 Thermostat Won't Work

If your thermostat has new batteries but still won't work, then it may be time to replace your existing thermostat. A programmable thermostat may have locks on the buttons, so it is best to check first if the thermostat won't work because the commands are locked. Otherwise, have a technician check your device.

Smart thermostats may link to a Wi-fi connection to get updates on the weather and other information that will help it create a more comfortable environment around the house. As such, check that the Wi-fi is working properly, and that the smart thermostat is connected to it to know whether the problem is with a faulty thermostat, or simply a connectivity issue.

How to Replace Your Thermostat

Replacing a thermostat will require some basic electrical knowledge, but this can be done at home without the help of a licensed professional. Thermostat replacement is similar to thermostat installation, and you'll need a couple of tools such as pliers, wire cutters, screwdrivers, and extra wires for good measure.

Step 1: Remove the Existing Thermostat

First, power down your HVAC system, and unplug the unit from its power source. Open the front panel of the mounted thermostat, and use the screwdriver to remove the unit from the wall plate. Disconnect the wires from the unit.

Step 2: Label the Existing Wiring

Separate the wires, and label them with some tape and a pen. This will help you organise your new thermostat installation, and make it easier for you to properly connect the correct wires later on.

Step 3: Install a C-Wire as Needed

If necessary, install the c-wire. This is most common in modern units, and allows homeowners to install smart thermostats into their HVAC systems. Connect the c-wire to the proper links, and label the wires as well.

Step 4: Install the New Thermostat

Install the new thermostat by connecting the correct wires to the proper links, and securing the connections. Mounting the back of the thermostat on the wall plate should help make the process easier.

Step 5: Secure the New Thermostat

Secure the thermostat on the wall, and place the face panel back on. The thermostat should not be wobbly, and the wires should be connected properly without much movement when the unit is used.

Step 6: Test Out Your Thermostat Installation

The last step is to check your thermostat: power on the air conditioning unit, and test the thermostat replacement. If the thermostat is working fine, then you've successfully replaced the thermostat. If the thermostat is still faulty, then you will need to unplug the unit and check the wiring connections again.

Air Conditioner Thermostat Replacement Cost

The cost of replacing an air conditioner thermostat greatly depends on the type of thermostat, and the model of the air conditioner. Most thermostats are priced at around $175, but more advanced models can go as high as $220 or more. 

Where to Buy Replacement Thermostat

#1 Home Improvement Stores

Thermostats can be found in most home improvement stores, and there are multiple models that work with different types of air conditioning units. Programmable thermostats are great for standard models, while smart units are good for automated cooling. There are also universal units that can work on most AC models.

#2 Aircon Repair

Getting your replacement thermostats at aircon repair shops is the best option when it comes to scouting for a thermostat. Not only do aircon repair shops have access to a wide catalog of HVAC components, they can also do the installation for you professionally!

At Luce Aircon, we pride ourselves in bringing only the best AC unit services across Singapore. Call us today, and let's see what we can do to give you a better cooling comfort with your air conditioning unit!