Classic/Antique Car Repair: 1951 Heater, shut off valve, hoses

Question
QUESTION: I'm restoring  1951 deluxe, and coming out of the firewall on the passenger side is a red hose and a black house and it is connected to a housing with a switch that looks like a by pass? What is this switch, and how does it mount, mine is hanging there with a pull cable that goes back under the dash. I cant find in any book this part of the car to show me what it is or how to mount it back to the car. Please help.

ANSWER: Tony, a 1951 what? The make and model would make my job a little easier. Let me know.

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QUESTION: 1951 Chevy deluxe, four door, with a 216 engine.

Answer
The color of the hoses only means that whoever replaced the hoses in the past used hose from two different manufacturers. The device that you are talking about is the temperature control for the heater. It is simply a shut off valve that is controlled by the Temp lever on the heater. Now there is another problem here. Id the heater an original GM heater? If so it should have the words Harrison on it some where as this was the division of GM that made it. In that time cars could be purchased without heaters and then the dealer would add a heater if the customer so desired. As a result there were a lot of cars out there with aftermarket heaters. Is the heater a factory installed? Let me know.