Of all the street rod topics we deal with, the one that generates the most questions is cooling-all sorts of cooling. It's a big subject that can include everything from the parts under the sheetmetal to the passengers who ride inside.
To address a topic this large, we put together a series of the most frequently asked questions to present to experts in their various areas of expertise. This month, we begin with air conditioning and radiators-two subjects that are near and dear to most street rodders. In future issues, we'll deal with fans, fan controls, water pumps, insulation, and all the other hot topics concerning cooling.
Air Conditioning1. How is the size of an air conditioner evaporator determined?
Hot Rod Air
The basic concept is to install the largest-capacity unit possible. We match evaporator coil to blower assembly and case design for maximum performance. Several factors also come into play. First and foremost is the size of the interior you are trying to cool (a coupe will require less Btus than a four-door sedan). The second factor would be the amount of physical space behind the dash-in some cases, you may need to have the evaporator hang down below the dash area a bit if space is tight. Keep in mind that when the system is on high and working to its maximum capacity-say, on a 100-degree day-it is easier to turn it down than to turn it up.
Southern Air
Our first heat and air unit was a mere 16 inches wide and 7 1/2 inches deep, and we soon learned that this fit tons of small rods, such as A models and most '30s cars. This unit would heat and cool these cars, but when it came to the '40s sedans, it was a little small so we began matching units to the size of the vehicle. We dyno-test all of our new units before we put them into production; so, if the customer gives us the car make and model, we have a unit for it based on the inside cubic feet of space in that car.
Vintage Air
We always recommend selecting the largest-capacity evaporator that will fit in the customer's vehicle. You can turn down the fan and adjust the temperature on a system if you get too cool inside your car, but you cannot make a unit that is too small cool a large area. Think about the climate-control system in the early stages of car construction. We manufacture mock-up units to not only determine fit, but to make it easy to fine-tune mounting brackets before hanging the actual unit. Many of our dealers loan these units for a nominal fee.
2. How is the size of the condenser determined?
Hot Rod Air
Condenser size is very simple: The larger the better; fill as much of the radiator core size as possible. You cannot oversize a typical street rod condenser. You should have a minimum of 230 square inches of condenser.
Southern Air
The size of the condenser is determined by the core size of the radiators. We use only parallel-flow condensers, and the salesperson will ask the year and model of the car when the kit is ordered. We will then supply a condenser that will fit.
Vintage Air
All of the components must be sized properly and matched. The evaporator absorbs the heat from inside the vehicle, and the condenser dissipates the heat to the air. We recommend selecting the largest condenser that will fit within the dimensions of the radiator core, and the use of parallel-flow condensers.
3. What engine/cooling system modifications are necessary to add air conditioning?