I have an oil burner / furnace that have been giving me problems for a month now. I have had it serviced 3 times already and the problem is still happening. Before calling the service company back I would like to have a better idea of what the problem might be, since they seem to be having no luck solving this issue.

Here is what is happening: The heat is on and running, then all of a sudden it just stops blowing hot air and starts blowing cold air constantly, even though it has not warmed the house to what I have the temperature set to. This usually lasts for an hour or two (though it has happened for all day recently); then it starts up again, blowing hot air instead of cold.

I have oil and it is not low. I have tried turning the system off, letting it sit for about 45 min and then turning it back on. Sometimes when I do this, in about 15 min the heat starts again; but this does not always work. I also have tried hitting the reset button, this does nothing at all.

The services people have given me several different reasons for this problem, anything from a wire that came loose (?), which they said they fixed, to my oil lines needing to be insulated (my furnace is in a crawl space and the tank outside), which I have done. The last service man had no idea what was wrong and so did a full routine 'tune up'. I have spent a lot of money on this issue and the problem still keeps happening. Can anyone help?