I have a Lennox electronic air cleaner, which is about 17 years old. There are two indicator lights. One is green for input voltage and one is red for output voltage. Both lights are always on. Even so, I do not think the unit is working. I do not hear any sparking or zapping of dust and I find that the house is dustier lately. How can I tell for sure if it is working or not? (I do clean the unit regularly)
Tika