Installing Old Air Products’ Hurricane Heat & Cool System

By Ron Ceridono – Images by the Author

When our buddy, Paul Willis, decided his new project would be building a 1955 Ford F-100 from the ground up he had two goals: one was to incorporate some classic mild-custom features like a tube grille, quad headlights, a rolled rear pan and early Ford taillights, among other modifications; the second was to include modern mechanicals, like a Chevy Gen V direct-injected L83 V-8, 6L80 automatic, and independent suspension on both ends. Of course, a climate-control system would also be part of the modernization effort, and for that he turned to Old Air Products for one of their Hurricane A/C, heat, and defrost units.

02 1951 Chevy underdash AC unit black plastic HVAC heater evaporator core housing — Old Air’s Hurricane heat/cool/defrost system is compact, which allows an operational cowl vent to be retained, if desired. The top two outlets supply the defroster ducts while the four below supply the center and side louvers on the dashboard.

Old Air Products was established in 1989 with the intent to produce a compact climate-control system that would fit any vehicle, be easy to service, and install. The result of their efforts was the popular Hurricane series that met all those goals. There are three variations of the Hurricane, the differences being where the connections exit the case to go through the firewall. The kit Willis chose was Old Air’s CAP-5100 series that is specifically designed for 1953-56 Ford F-100s. It provides A/C, heat, and defrost functions.

03 1951 Chevy AC evaporator core ports heater core lines front view HVAC unit — The Hurricane system for 1953-56 F-100s have A/C and heater connections that fit through the firewall, simplifying the connections. The three threaded inserts accept the mounting plate that attaches to the firewall.

Included in the complete Hurricane kit is the heat, cool, and defrost unit, mounting hardware, switches, wiring, electronic heater control valve, receiver/drier, duct hose, hardware, compressor, custom fit condenser with custom tubes and brackets, and A/C hoses—everything necessary for installation. Old Air kits come equipped with a binary switch to protect the A/C system from excessive high or low system pressures. An optional trinary switch is available (PN 24-0103) to protect the compressor from head pressure that is too high or low, but will also activate the electric engine cooling fan as needed.

04 1951 Chevy AC evaporator input output port close up fittings heater core plumbing — Here the mounting bracket has been attached to the evaporator assembly. Note the four studs that will secure the assembly to the firewall.

Old Air offers pre-crimped, universal hose kits but for our application we opted for new Simple-Crimp hose kit. It comes with a reduced-diameter hose that is easier to install and route compared to standard barrier hose and comes with a variety of fittings and the required clamps.

When selecting an A/C compressor, Old Air has several to choose from, including the popular and reliable Sanden 508. These compressors have five cylinders and a displacement of approximately 8.4 ci per revolution. However, for LS applications Old Air recommends using the Sanden 709, which has seven cylinders and a slightly larger displacement of 9.36 ci. These compressors put out more volume at idle and are suggested to eliminate possible vibration issues and better cope with potentially high engine operating speeds. Since the L83 Chevy didn’t come from the factory with a power steering pump (which was needed), Willis used brackets from LSX Innovations that mount both a power steering pump and will accept a Sanden 508 or 709 compressor.

05 1951 Chevy AC firewall template cutout heater core access port custom install — Included in the Hurricane kit is a template for the 1-1/4 inch hole necessary for the evaporator drain hose—that’s the only modification to the firewall required.

Installing the Old Air Hurricane interior unit containing the A/C coil and heater core couldn’t be easier. It mounts to the firewall using factory holes; the heater and A/C hoses pass through the existing opening in the firewall for the original heater blower motor. The discharge louvers and switches to operate the fan, A/C, and heat normally mount to the lower edge of the truck’s dash. However, in this case the optional electronic slide control was found to be a perfect fit in the 1957 Ford passenger car dash Willis had gone to great lengths to make fit.

06 1951 Chevy AC firewall port fittings installed LS engine bay view — Here the evaporator has been bolted in place. A rubber grommet for the A/C and heater hoses fits the factory heater motor hole in the firewall; a grommet for the drain hose is also included.

In most cases the custom condenser assembly Old Air offers for F-100s is the way to go. It includes mounting brackets that use the OEM bolts to mount the condenser, receiver/drier, and pre-formed aluminum lines to pass neatly through the core support. However, the aluminum radiator the truck was already equipped with included a condenser that was the proper size for the application, so that’s what was used.

07 1951 Chevy AC evaporator unit mounted underdash interior HVAC wiring visible — The compact evaporator assembly fits easily behind the dashboard and is virtually hidden from view. The hose at the bottom of the case drains any moisture that accumulates in the case.

Installing the heater and A/C hoses is quick and easy. The heater control valve can be located anywhere that is convenient. It is important for LS and Coyote engines; a bypass heater valve is used to recirculate the coolant/antifreeze back to the motor. We particularly liked the Easy-Crimp A/C hoses as they could be cut to the exact length needed and the ends installed without the crimping tool the standard hose requires. Old Air’s Jose Balderas points out, “When using reduced-diameter barrier hose it is important that they make sure to keep it away from hot components underhood. It can affect the performance of the system because with the hose having a smaller diameter, it is more susceptible to heat and can start to change the high-pressure liquid in the liquid line into a gas before it reaches the expansion valve. With the standard hose kit that is not as much of a worry because of the hose thickness.”

08 1951 Chevy AC floor vent assembly with capillary thermostat temperature control — This is the air inlet grille for the system. It mounts the adjustable thermostat for the A/C system that cycles the compressor to prevent the A/C coil from freezing.

As the purpose of a climate-control system like the Hurricane is to control the temperature of the passenger compartment, it’s always advisable to add insulation to the roof, floor, and firewall to optimize the performance of the heater and A/C. Make sure the weatherstripping around the doors and windows is in good shape; tinted windows will help reduce interior heat gain in the summer, making the A/C more effective. There are also mechanical considerations when installing a heat and cool system. The engine must be equipped with an effective fan (mechanical or electric) that provide sufficient air through the radiator and condenser. In addition make sure the charging system is capable of handling the increased electrical load and is properly grounded to ensure proper operation of the electronic controls.

09 1951 Chevy AC floor vent grille mounted to underdash HVAC housing interior view — With the inlet grille in place, the thermostat’s capillary sensor tube (that coil above the knob) is inserted into the A/C coil at a designated location.

Once all the components are in place all that is left to do is charge the system with refrigerant. This is a job for an experienced technician as it requires evacuating the system with a vacuum pump for a minimum of 45 minutes, then adding 28-32 ounces of 134a refrigerant. Once charged, a dedicated set of A/C gauges should indicate the pressure on the high side of the system (the discharge and liquid lines) to be approximately 2-1/2 times the outside air temperature. On the low side (suction line) the system pressure will initially be 35 to 45 psi then and drop lower as the passenger compartment cools.

10 1951 Chevy AC heater core lines routed through firewall LSX engine swap — The heater hose connections on the L83; the heater control valve has 5/8-inch connections. Old Air Products includes hose adapter sleeves for 3/4-inch heater hoses with their bypass heater valves. NAPA offer a hose that is 3/4 inch then necks down to 5/8 inch under PN NBH 10083.

Old Air’s complete Hurricane package includes everything necessary for the installation. It comes with detailed instructions and their helpful tech experts are a phone call away, if needed. It’s an easy way to make your F-100 cool.