Selecting The Right Evaporator


Gen II Compac

The evaporator unit, which mounts inside the car, is called that because it absorbs heat from the warm air inside the cab which evaporates the refrigerant running through the evaporator coil. That heat is carried off with the refrigerant to be given off to the cool air flowing across the condenser at the front of the car. Whether the system is a built-in, behind-the-dash unit, or a below-the-dash style unit, the job is the same.
Since the rebirth of street rodding in the ‘70s, the goal of most car owners has been to conceal as much of the air conditioning system as possible purely for appearance considerations. Our challenge has always been to build a compact enough evaporator unit to fit behind the dash in smaller, early model classic cars, trucks and street rods. When component size was reduced, compensation for efficiency became necessary. Blower motors can turn faster and evaporator coils can be fed better, but in most cases when component size was reduced, capacity also diminished. However, after thirty-six years of engineering and testing, we have overcome most of the early limitations. Through our incorporation of computer modeled “virtual” flow testing, servo motor-driven air doors (a Vintage Air first), and


Gen IV Magnum

super efficient cooling and heating coils, we can now deliver performance far beyond the earliest aftermarket systems. Our proven Gen II and our revolutionary Gen IV systems can perform as well as any OEM system today. See Page 11 for further explanation of the benefits of our revolutionary Gen IV technology.

Installing The Evaporator

When installing the evaporator, it must be set in the car with the drain pan and tubes down so the condensation will drain. The dash air outlet louvers should be positioned so they blow on the driver and passengers directly, under or through the dash when possible. The louvers should be as close to the evaporator as possible. Other locations usually produce disappointing results. In all cases you must not block-off any air outlets on the evaporator case to avoid internal air turbulence and reduced performance. If used, the thermostat capillary tube should be inserted at least 4 inches into the evaporator coil fins. The blower should always recirculate the inside cabin air. Introducing outside air is not necessary and will cause the system to work much harder to maintain comfortable temperatures. Where your refrigerant hoses must pass through sheet metal, use either a refrigerant hose grommet or a bulkhead fitting. See Pages 78 and 80. Your drier should always be positioned to produce a “liquid seal” at the pick-up tube (this will be vertical for most driers). We also recommend mounting the drier inside the passenger area whenever possible. Where your suction line and liquid line run parallel, they can be tied together. The difference in temperature will actually help the refrigerant in each line do its job.

Insulation Is A Must

An air conditioner has to remove heat faster than it is added into the cabin of the vehicle, so it is important to reduce the heat entering the vehicle. Just like reducing weight on a race car so the engine can do more, we reduce heat load in a car by insulating thoroughly, sealing doors and windows, and even tinting the glass. This should be a mandatory step when adding an air conditioning system to any vehicle and will ultimately determine how well the system performs. (See Page 90-91)

This information should give you a basic understanding of automotive air conditioning and aid you in selecting the proper components for your particular needs. We encourage you to call one of our distributors or our technical staff with any questions you may have about air conditioning your classic car or truck, street rod or other special vehicle.