I have a HEIL SP80 gas furnace. When I turn it on the ignitor comes on and the flame is there, but it doesn't ignite the burner and the blower doesn't come on and start blowing warm air. If I disconnect a relay wire it resets and will come on, sometimes it takes a couple of times doing it. After the set temp is reached, and it kicks off, it doesn't come back on. It will keep cycling through but the blower will not come back on by itself again. Can anybody please help?