I have a Trane XL80 gas furnace. It also has a heat pump for ref. Today, the temp in our home dropped and I noticed that the furnace was not working. I opened it up, and vacuumed it out, and have no idea why it started working. All was good!

However, hours later, the temp is again dropping. I opened it up again and noticed that on the right side there is a white plastic box (model 50E-47-60)with a bunch of wires running out of it at the bottom. On the left side bottom of the box, there is a small red light blinking. It states that if the red light is steady to replace the box. It also states that if the red light is blinking to consult the owners manual. Our home is 18 years old, and we are not the first owner. NO MANUAL.

Does anyone have an idea what the problem is? Is there a fuse, circuit breaker somewhere or?? Earlier this morning, a ribbon or?? Turned red hot to ignite the gas after a few moments. This evening, the ribbon or heating element does not turn on.