My '84 242 (non turbo) heater is always on (not the fan... the air is always _hot_). I read about the 700 series fix for 'Heater Won't Completely Shut Off Hot Air' but after removing my glovebox I think the 240 is different. The Haynes manual diagrams are terrible and I can't seem to figure it out. From what I can see the hot/cold slider is operating the cable and attached to a flap which seems to go through its entire range of movement. Sorry for all the technical terms ;-)

This board has been very good to me in the past and I know someone else has had the same problem... any ideas?

Thanks again!

-John

Use the link that Mike sent you. Remove the drivers inner kick panel or sometimes called the center console panel. The valve is located to the right of the gas pedal. The sensor is inserted into the blower housing and the valve is right below it. Good luck. You might want to check the cable that attaches to the slide control at the center console. Also check the end that connects to the healer valve.

The valve probably needs simple adjustment. Problem is that valve body is made of flimsy sheet metal which bends at the thermocoupling tab. (The thermocouple itself never goes bad unless someone breaks it.) Luckily, the sheetmetal tab has a small adjusting screw to compensate for metal fatigue and to adjust temperature control at the dashboard lever. This small screw, usually phillips or sometimes hexhead, when turned clockwise, tightens the thermocouple piston against the spring/valve assembly, and thus tightens the water valve, and thus hot water entering the heater core is turned off. DON'T DISSASEMBLE ANYTHING until you've tried this; the screw head can be seen, look closely, within the assembly, it faces the driver. Experiment. Turn on engine; turn on heater fan. Place dashboard control in MIDWAY position; turn the screw in one turn to take up the slack on the thermocouple piston. Look carefully to see whether the thermocouple piston barely TRIPS the spring mechanism/valve plunger,stopping the flowing hot water. You may need to turn in screw more or less. Without hot water the fan-air cools down the thermocouple, releasing its piston, which in turn relaxes the plunger and opens the valve, introducing hot water again. It cycles over and over again, producing an AVERAGE temperature in the heater core according to how the screw and dash lever is set. Very good system and simple adjustment once you get the hang of it.

http://www.brickboard.com/RWD/index.htm?id=781119

Another inexpensive fix to a bad heater valve is to just take it out and put a ball valve in line with the system where the coolant comes through the firewall. Cost me about $4 for the valve (from the plumbing section of home depot - I think the 3/8 one fits standard heater hose well) and another $5 or so for the heater hose which you may as well replace while you're in there. It controls the (hot) coolant flow to the heater core as well as the fancy and expensive gate valve, which tends to corrode open.

Look by the drivers right knee after you remove the kick panel. Either the cable is loose or the heater valve is broken.

I'm leaning towards the heater shut off valve, only cause I had one go bad on a rust bucket 245 years ago. New ones weren't cheap at the time and because of the condition of the car, I simply pinched off the coolant "in" line in the engine compartment near the firewall with two 1 inch dowels and 2 worm clamps. I removed them in the winter as needed. It cost 20 minutes of time and no cash. Good luck!
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It's Jim (in Hartford CT)