Came out to call for a system not heating properly. Customer stated that over the weekend the unit stopped working and wouldn’t come on at all. I checked the system over and found unit to have no power from plug. Customer checked the breakers and reset a furnace breaker. I plugged system back in and the unit started to operate again. After letting it go through heating sequence, I noticed the ignitor was still glowing and the blower took longer than usual to kick in. Found the control board is sending constant power to ignitor and the blower relay is potentially failing. Let customer know that the control board needs to be replaced. Unit is over 20 years old, so I discussed repair vs replacement. He has a home warranty company and wants to see what they can do about the issue before moving forward with repair or replacement.