We have an 18-year old Carrier Weathermaker 58 SXC 080. Twice the blower has kept running after the temperature has been reached and the flames have gone out. The house temperature goes down as the furnace blower blows cold air through the house. Turning off the thermostat does nothing to stop the problem.

I called a local HVAC person after the first time, and he was kind enough to help me over the phone. Basically, I banged in between two red wires with the butt of a screwdriver, turned the gas and electricity back on, pressed the manual reset switch, and trned on the thermostat. After the first time, I hoped it was a one-time thing due to a dirty filter (though not terribly dirty). After replacing the filter, it happened again a couple of days ago. I got the furnace to work again without problems over the weekend, but I'm starting to think that a switch may need to be replaced. Any guesses as to what's wrong/cost to fix (I'm in the Washington DC area)?

In the U.S. there's a tax credit right now for installing high-efficiency equipment (30% of the total cost to install, up to $1,500). Should I replace the furnace and A/C (also 18-20 years old) now, as well as the 19-year old hot water heater?

Thanks for your advice on these specific and general questions.

Vaandjay

P.S. If all these things should be replaced, any recommendations on where to get a home equity loan? ;)