I have a Day & Night furnace w/ an A/C unit attached. This summer the A/C unit stopped working. I did have an A/C guy come out and verified it needed some sort of coolant. Once that was charged up, it seemed to work for awhile, but soon it stopped again. I am suspecting a leak. Right now it's winter so I don't care so much about that.

The A/C problem seemed to start when my 15 year old decided it was time to troubleshoot the problem on her own, so she took the original 1985 thermostat apart. Thinking perhaps THAT caused the problem, I bought a new Home Depot RiteTemp model. I was careful to get the G and Y and RH, etc. wires connected properly.

MY PROBLEM: The unit when set to heat starts up for a second (you can hear it) but quickly shuts down again. This happens about once every 15 minutes, never staying on.

The fan does run when I turn that on. My pilot light is automatic and the gas is on.

I appear to have 110v coming into the unit because I can turn the fan on and I can see the small blower fan on the unit spin when it's on heat and it fires up momentarily.

Is it possible this new thermostat is not broken out of the box? My old 1985 unit did work the heater before I took it off and replaced it.

I've uploaded photos of the unit, but I'm not sure if they made it.

UPDATE: I took the two sheet metal screws out that hold the igniter assembly so that it can drop down for me to see if it's firing when the unit turns on, and it is. I see spark jumping across the small gas opening, but gas ignites. The gas is turned to on.