I live in an a later 1970's manufactured home with a Intertherm MAC 1199 furnace. For a couple of years I have had the following problem with the furnace.
Initially the regulator went bad and it was replaced by a local HVA contractor. The contractor told me that the exact replacement part could not be purchased any longer but they could adapt a modern regulator. The HVA contractor installed new regulator and the furnace seemed to work just fine. There was a much more pronounced window rattling start ignition but everything seemed just fine.
However, ever since the new regulator was installed the pilot goes out when and only when the temperature drops below approximately 20 degrees!
The HVA contractor came out several times and kept turning up the pilot light. The problem persists and the HVA contractor now on longer returns my calls...
So I have personally replace the thermocouple and made sure that I have a correctly adjusted pilot flame. The gas company tells me that the pressures are correct.
This morning I woke up to a very cold house and 18 degrees outside.
The VERY interesting thing I noticed this morning when I went to light the pilot was that my long neck lighter kept blowing out when I put it into the access door to light the pilot!
In fact there was a very pronounced draft running into the little access door. Enough air flow such that I could not maintain a flame on my lighter when placed just outside of the access door nor could I strike a flame on the lighter if it was inserted into the pilot area!
Once I had a fire going in the wood stove and the sun came up (warming the roof?) I went back and the air flow into the furnace was minimal, the lighter could strike a flame when in the furnace and the pilot light worked perfectly!
The furnace has been running fine all morning and I am REALLY STUMPED!
Am I nuts or what?
All info and comments Greatly Appreciated!