Looking inside most of the customized classic trucks found at events across the country would lead the casual onlooker to believe they all came equipped with factory air conditioning. But while Packard became the first car to introduce factory air conditioning in 1939, most pickups weren’t so blessed until the ’60s. Fortunately our friends at Vintage Air began developing aftermarket systems in 1976 that made it easy to retrofit any car or truck with a contemporary climate-control system.
While adding A/C to an early truck isn’t anything new, something that is becoming more common is replacing an original factory system with something more efficient, and our 1973 Ford is a perfect example. While the heat and cool system in our truck was fine when new, time and lack of technology have caused it to be trouble prone. The first problem became apparent when the vacuum-activated dash control developed a mind of its own. Due to what seemed to be miles of rubber hose, all of which had deteriorated, and a dicey vacuum motor, the system would change from defrost to floor outlets then maybe to the dash registers. But the most annoying behavior was when the flapper door would open sporadically, allowing cold air into the cab when heat was desperately needed.
If the control issues weren’t bad enough, the heater core began seeping, which soaked our new carpet—meaning the entire underhood unit had to be removed for repair. Of course that meant the A/C would have to be disconnected and that meant we’d have to convert to 134A refrigerant from the original ozone depleting R-12. With all things considered, it was time to update to a new Gen IV Vintage Air heat and cool system.
In operation, the heater portion of any heat and cool system passes hot water through a mini radiator and a fan blows air through the core to provide warmth for the passengers. While that’s simple enough, cooling the air is a little more complicated, but essentially air conditioners make the air cold by removing heat.
The major components of an automotive air conditioning system are the compressor, evaporator (inside unit), condenser (outside heat exchanger), hoses, fittings, drier, safety switch, and, of course, refrigerant. In operation, liquid droplets of refrigerant flowing through the evaporator absorbs heat and turns to a vapor, the compressor draws the low pressure vapor from the evaporator and pumps it through the condenser where the heat that has been absorbed dissipates in the ambient air and as the refrigerant cools it becomes a high-pressure liquid. From the condenser the refrigerant goes to the receiver/drier where the vapor and moisture are removed, it then passes through the expansion valve, which atomizes the refrigerant and turns it into a stream of cool, low-pressure droplets—and the cycle begins again.
Gen IV Technology
Vintage Air’s Gen IV units include a long list of features that were previously found only on modern OEM systems, such as fully electronic servo operation that eliminates vacuum motors or control cables for operation, increasing reliability and ease of installation. By using electronically controlled servo motors the air doors can travel further, which allowed Vintage Air to design evaporator cases with increased air volume in both the heat and cool modes. Thanks to these to solid-state controls warm and cool air can be blended for precise temperature control and the optimum dehumidified defrost mode. And for those with engines that have lumpy cams and low-manifold vacuum at idle, electronic servos will eliminate the tendency of vacuum controlled units to behave erratically with a mind of their own. Typically these engines have low-manifold vacuum at idle, which can make vacuum-operated accessories like A/C systems seem to have a mind of their own—servo motors eliminate any such erratic operation.
When installing any A/C system something that should be included is a safety switch. There are two types, the binary pressure safety switch (Vintage Air PN11078-vus), which disengages the compressor clutch in case of extreme low system pressure resulting from a loss of refrigerant (extremely important since an A/C system relies on refrigerant to carry lubrication through the system) or excessively high head pressure (406 psi) to prevent compressor damage or hose rupture. The second type of safety switch is the trinary (PN 11076-vus) that combines high/low pressure protection with an electric fan operation signal at 254 psi.
With the Vintage Air Gen IV system securely mounted under the dash we were able to connect to the original dash outlets and mount the new control panel where the original had been. An unexpected benefit of the new system was the elimination of the huge factory box of climate-control parts under the hood. It makes spark plug and rocker cover access much easier, and for show trucks (which this is not) the firewall can be cleaned up considerably.
Our Vintage Air Gen IV system works perfectly, hot or cold temperature in the cab is easy to control, and the defrosters work great. And best of all the system does not have a mind of its own.
Vintage Air has universal heat and cool systems for virtually any application, as well as their Sure Fit line for specific vehicles, such as this one for 1961-1966 Fords.
For our 1973 Ford we used universal components. We fabricated a filler plate to mount the new Vintage Air control panel and cover the hole for the system’s original vacuum controls.
This is the big, bulky original housing for the heater core, A/C evaporator, and the blower motor. The entire assembly was removed.
We wondered why the original A/C was working poorly. It was plugged with a combination of sealing foam from the inside flapper door and hair from our constant companion, Babe the Wonder Dog.
This is the new Vintage Air Gen IV heat and cool unit. Owing to its more efficient components it’s more compact yet more efficient than the OEM system.
Thanks to these electronic servomotors the doors inside the evaporator housing can travel further for increased airflow and warm and cold air can be mixed for precise temperature control.
Shown here are the new Vintage Air defroster ducts and the massive factory version. Getting rid of it and all the vacuum hose the original system required cleaned up the area behind the dash
This is the original air intake from the plenum in front of the windshield that connected to the heating system. We made a cover plate to close it off.
To retain the original dash outlets we had to modify the hose connections by making adapters with oval holes from flat plastic.
The original ducts for the dash outlets had rectangular ends. We used epoxy to attach oval connectors from Vintage Air to flat plastic and then epoxied the “adapters” to the original registers.
With the new control panel installed and the original dash vents in place the conversion isn’t noticeable until you turn the system on and the improvement is obvious.
A cover plate was made to fill the huge hole left by the original heater-A/C box. It has a small hole to allow access to the new heater and A/C hoses.
Vintage Air supplied a small panel and rubber grommets to route the heater and A/C hoses through.
This is the electronic heater control valve. It is directional and must be oriented correctly in the hose leading to the heater core.
The new Vintage Air condenser has two different fittings—when installing it the #6 line should be located on the bottom and the #8 at the top.
This is the receiver/drier. We mounted it behind the grille on the core support. It should always be changed whenever the A/C hoses are disconnected and the system is drained of refrigerant.
We had previously installed a new Sanden A/C compressor with the serpentine belt system, but it had never been run. Note the new hoses: a #6 is the high-pressure hose from the condenser/drier to the evaporator; a #10 hole comes from the evaporator to the suction side of the compressor; a #8 hose connects the discharge side to the compressor to the condenser.
When crimping hoses a hole in the ferrule of beadlock fittings ensure the hose is seated properly.
Beadlock fittings have a ferrule that is attached to the tubing; crimping the ferrule locks the hose in place.
This is a hydraulic crimping tool from Vintage Air. It comes with a complete selection of dies and will make safe, secure crimps.
This is how a properly crimped beadlock fitting appears. The metal barrel on the fitting should be crimped evenly all the way around.
To prevent damage and ultimately refrigerant leaks when installing fittings, the O-rings must be lubricated with the proper compressor oil.
Part of every A/C system should be a safety switch—this is the binary type. It will have two connections and is placed in the wire leading to the compressor clutch.
This is a trinary safety switch. It performs the same function as the binary switch and will also activate an engine cooling fan. Even with a mechanical fan it’s wise to use a trinary switch in case an electric fan is added later—it eliminates the need to drain and recharge the system to change the switch.