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.

Flame sensor will be a small steel rod in front of farthest burner away form igniter and have a single wire (usually orange) going to it. No heat, no gas, no ignition. Two green lights and fan does ... We just had a power outage and it is now restored.

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.

The system should have a reset switch. Turn it to “OFF,” and wait 5-10 minutes to give the gas time to dissipate. Hold in the reset switch and use either a match or lighter to relight the pilot light. Try to do this step relatively quickly so too much gas doesn't dissipate around the furnace.

Turning the power off for approximately 20 seconds and turning it back on again will reset most modern gas furnaces. Some furnace models can power on again after leaving the lockout for 1-2 hours. The cleanliness of the flame sensor of a furnace is very important.

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.

If the thermostat clicks but the AC or furnace doesn't turn on, most often it's because the filter is clogged. A blocked filter will restrict airflow. The particles it's designed to trap eventually clog the filter media, and the system will be unable to generate heat or cool air.

Broken Flame Sensor

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.

Why won't my pilot flame ignite? ›

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.

Check the Spark Igniter

If gas is coming out of the pilot but it still won't light, the spark igniter could be the problem. You should clear out any debris between the igniter and thermocouple. Blow compressed air into the pilot area, wait a couple of minutes, and then try again to see if this fixes the problem.

The first step in diagnosing the issue is to check your thermostat settings. Ensure that it's set to “Heat” mode and the desired temperature is higher than the current room temperature. Sometimes, the thermostat might be accidentally set to “Cool” or “Fan Only,” causing the furnace to run without heating.

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.

Look Out for Fuel & Ignition Issues

You may have an ignition system or fuel supply issue if your furnace doesn't produce heat after turning it on. You can check if you have fuel issues through the following steps: Look at the gas supply line to make sure the gas valve is open.