ll_45

I have a 66 mustang convertible and the heat coming from the floor is uncomfortable esp. in summer. I have adjusted the cables and can hear the metal door open and close when I move heater controls, yet when I drive sometimes the heat feels like it is on. Sometimes it is on left side and others the right. Where do I start???

JamesW

There are a couple of things you can do to improve this. The heater box over the years lose their ability to seal when doors close. This can be rebuilt. The whole heater box can be removed relatively easily and a small rebuild kit can be ordered from most Mustang parts suppliers. These kits have precut foam patterns that are glued to the doors and sealing surfaces. This will substantially cut down the hot air blowby.

Another option, which is actually used in later models, is to install a valve in line to the heater hose. If you turn off the hot water, the interior will stay cooler. This may be easier and faster to accomplish.

You can go to an auto parts store and ask a mid 80s heater line switch. Both vacuum and mechanical were made. I preferred the plastic style as opposed to metal, because they do not corrode as fast.

YOu can see the line value in this photo, just above the Pass side valve cover.

ll_45

Thank you.

tx65coupe

I agree with what he said. I had actually thought about doing this to mine. I completely rebuilt my heater box and even with the heat off a small amount of warm air makes its way into the car.

Also, If you really can't control the heat at all, then one of the cable might be broken or have come off of the heater box.