Can someone give me advice on the heater problem in my 1987 Toyota Celica GT convertible ? The car has 95,000 miles on it. After the car has warmed up, if I slide the Cold/Heat lever to Heat it will sometimes put out hot air, and some times it won't. If it is putting out hot air and I drive down the road all of a sudden the heat will go off and become cold. Then as I drive on with cold air, PERHAPS it will revert back to hot air, but most of the time it stays cold. Other times it will revert back to hot and stay hot for the duration of my trip - maybe 2 hours. At the times that the heat goes off, the hot water valve under the hood is still in the "hot" position, (the valve lever position is still nearest to the firewall). I am not using the "Automatic" button, but using the manual push buttons, such as floor only, floor and upper, upper only, etc. I live in a small town and my mechanic shop doesn't mess with "foreign cars" much he says and definitely he does not mess with anything under or behind the dash. His solution was to install a modified choke cable under the dash, hooked to the hot water valve under the hood, disconnecting the original push-pull cable that ran thru the firewall to the valve from somewhere under the dash. HORRIBLE AND IT DIDN'T SOLVE THE PROBLEM. Apparently there is a motor/device under the dash that must control airflow to or away from the heater core as it also moves the hot water valve to heat or off. As far as I know the mechanic DID NOT check the heater core for any form of blockage. The mechanic also said that the car is so old that probably I won't be able to locate the under-dash motor/device even if I knew what it was called, or where to look for it. So, he shrugged his shoulders and sent me on my way, apparently expecting me to use the car in the summer months only. My closest Toyota dealer is about 4 hours away, and I'd like to know what is causing the problem and what the motor/device is called, where is it located, and where I might find and buy one, before I leave it with Toyota and rent a "loaner". Or.......if there is some other problem than this mysterious device. Also what it might cost if still available. ANYBODY ELSE HAD THIS PROBLEM ?? Winter is coming on and I NEED the heater........................... Thanks for any help any of you might offer. I'm located in southern Iowa.