Ruud Achiever 90 Plus Not Igniting (2024)

FAQs

Why is my furnace turning on but not igniting? ›

If your gas furnace initiates the start cycle but does not fire up, it's likely because of a faulty, damaged, or dirty ignitor/sensor. This is a very common furnace problem — you can try to clean the sensor and replace the ignitor.

Defective Igniter or Pilot Light

If it makes a clicking noise but your furnace won't ignite after its combustion cycle, then it's more than likely going to need to replace the electronic ignition systems.

Check if the gas supply is on, the pilot light is lit (if applicable), and there are no blockages in the gas line. If everything seems okay, it might be a problem with the ignition system or the thermocouple. It's best to have a professional technician take a look to ensure it's safe and properly fixed.

Reset The Furnace Ignitor

Find the burner door on the furnace and look behind it to find the ignitor. Turn it to “OFF” and wait for five minutes. After you wait, turn it back on and return the door to the burner. It is important to make sure the switch on the door is properly engaged.

If the igniter is glowing, but the burner is not lighting, the igniter may be weak and still be at fault because it requires a certain amount of current draw to open the valve. This check requires the use of an amp meter and should be performed by a qualified person.

The Short Answer Is: Warning signs of a bad furnace ignitor include the furnace not starting or heating, a noticeable clicking sound without ignition, or frequent short cycling where the furnace turns on and off rapidly. Additionally, if the ignitor appears cracked or discolored, it may need replacement.

Most likely, your furnace is making a clicking noise and not providing heat because your furnace's spark igniter is trying to ignite your pilot light or burners but is failing to do so. In other words, there's an ignition system malfunction that needs to be fixed. Otherwise, your furnace won't start.

This is usually due to your AC's relay turning your AC on and off. If that clicking is loud and/or continues for more than a few seconds, you probably have an issue with a broken relay or a worn wire in your thermostat. Contact a professional technician to identify and fix the problem.

If your furnace is not turning on you should first check if the filter is clean. Dirty filters cause insufficient airflow and can prevent the furnace from starting. Other reasons it won't start can stem from improper thermostat settings, forgetting to turn on the gas line, or faulty pilot light.

Why is my furnace not lighting a flame? ›

If your furnace won't ignite, the source of the issue may be a broken flame sensor. The sensor is responsible for turning off the gas burners to avoid gas buildup. Once this component starts to malfunction, it may stop the burners from igniting altogether.

In many cases, the reason that you can't get your pilot light to ignite is that the pilot tube is clogged. This is a small metal tube that supplies the gas needed to ignite the pilot and keep it lit. The pilot tube often becomes clogged with debris, and this will prevent gas from flowing to the pilot light.

Clogged or Dirty Air Filters

A dirty or clogged air filter can restrict airflow, causing your furnace to overheat and shut off the burners. In such cases, the blower fan will continue running, but no warm air will be distributed throughout your home.

For your furnace to ignite, the thermostat must be set on heat mode. If it's not, your furnace won't ignite the burners. Another possibility is that the thermostat's connections or sensors are faulty. First, make sure the thermostat is set to heat mode.

If the hum occurs when the motor is on but not turning, the capacitor may be damaged and, if so, should be replaced. This could result from a poor quality capacitor or a blocked filter. Humming when the blower is off usually indicates that the pilot light needs to be readjusted to the appropriate level.