We’ve got some exciting news from Classic Auto Air. The longtime vintage Mustang air-conditioning experts now offer a true climate control system for ’65-73 Mustangs. It doesn’t clutter the dashboard, transmission tunnel, or foot well area. Best of all, CAA’s new Perfect Fit climate control system delivers air-conditioned comfort in summer and warm feet in winter.
As its name implies, Classic Auto Air’s Perfect Fit climate control system goes behind the ’65-’73 Mustang dashboard and glides right into place for a snug installation hidden from view. Not a one-size-fits-all system, the CAA unit is designed specifically for classic Mustangs, replacing the factory behind-dash heater/defroster assembly and operating like a late-model climate control system to provide heating, air conditioning, and defrosting via the factory heating controls.
When you contact Classic Auto Air for a Perfect Fit system, chat with the representative about what you’d like your system to do and how you’d like it to look. For this article, we’re installing a ’65-’66 CAA Perfect Fit system into our Project Reclaim ’65 Mustang fastback from Mustangs Plus and The Restomod Shop.

Classic Auto Air’s Perfect...

Classic Auto Air’s Perfect Fit system is designed specifically for ’65-’73 Mustangs; there’s a system for each generation. Perfect Fit tucks nicely behind the instrument panel with no surprises. It functions from your Mustang’s factory heater controls, which keeps the original factory appearance. Like factory air conditioning systems, there’s a thermostatic compressor switch to activate the compressor, which operates in concert with the Perfect Fit fan switch.

Mustang firewalls from ’65-’73...

Mustang firewalls from ’65-’73 generally look like this, with one opening for the factory fan motor and two passages for heater hoses. Between the heater hose passages and fan motor opening is the evaporator drain passage located 13⁄8 inches toward the tunnel and 5⁄8 inches down from the heater attachment bolt hole. There’s a template in the kit to help you get it right. Classic Auto Air recommends a 5⁄8-inch hole for the drain hose. Use a rubber grommet around it to prevent chaffing.

Perfect Fit refrigeration,...

Perfect Fit refrigeration, heater hose, and drain lines look like this prior to installation. Refrigeration lines are at 9 and 3 o’clock. Heater hose connections are at 12 and 6 o’clock. Evaporator drain line is at 5 o’clock. You can use the clear hose provided or you can also use a ’67-’73 factory in-dash evaporator drain hose with a spring clamp.

Richard Bramlett of The Restomod...

Richard Bramlett of The Restomod Shop installs our Perfect Fit system. A couple of 3⁄16-inch holes need to be drilled for the mounting brackets. Use sealer on the screw threads to keep cowl vent moisture out. Classic Auto Air provides a cowl vent plug, which installs in a matter of minutes to permanently close off vented air on the right-hand side.

Once installed, Perfect Fit...

Once installed, Perfect Fit stays clear of feet and flush with the dashboard.

On the engine side of the...

On the engine side of the firewall, Perfect Fit looks like this, with heater and refrigeration lines protruding through the firewall opening that originally accommodated the blower motor. This is a nice, compact package that doesn’t consume space on either side of the firewall.

This escutcheon dresses up...

This escutcheon dresses up and seals the firewall connections. Once in place, 3⁄16-inch screw holes are drilled at 12 and 6 o’clock positions.

Air-conditioning line O-ring...

Air-conditioning line O-ring seals must be treated carefully and lubed with refrigeration oil to ensure a good seal. Do not overtighten. Be very careful joining lines to prevent seal damage because it’s so easy to pinch and damage these little guys. Make sure your fingers are hospital clean.

The receiver tank installs...

The receiver tank installs behind the right-hand shock tower. What makes the Perfect Fit system ideal is its clean installation where key components like this receiver tank are installed out of sight.

The hot water control valve,...

The hot water control valve, which is cable controlled, installs like this in the heater hose that runs to the water pump. Coolant flow must be toward the water pump, not from.

The condenser is installed...

The condenser is installed next, which is a perfect fit for the ’65-’66 radiator support. Where it gets complicated is Reclaim’s fiberglass front valance, which creates some clearance issues that we will have to work out later.

We’re going to install a 90-degree...

We’re going to install a 90-degree connection at the condenser, which calls for a 1-inch hole in the radiator support just above the framerail. The valance must be modified with a grinder to make room for the 90-degree bend.

The valance must be modified...

The valance must be modified with a grinder to make room for the 90-degree bend. The reason this installation differs from what you will see in the Perfect Fit kit is the front dress we used on Project Reclaim’s 331ci engine, which relocated the air conditioning compressor lines to the right side of the engine.

Completed condenser installation...

Completed condenser installation looks like this, with the 90-degree line out of sight and through the radiator support.

Richard routes the air-conditioning...

Richard routes the air-conditioning suction line along the right side. If you’re going with the stock V-8 compressor location used in the Perfect Fit kit, these lines are routed on the left-hand side across the firewall to the right side.

Richard secures the lines...

Richard secures the lines with rubber-lined Adel clamps for optimum line security.

Because we’re running an aftermarket...

Because we’re running an aftermarket billet front dress with serpentine belt drive, compressor lines are relocated on the engine’s right-hand side. The Restomod Shop will fabricate lines from our Perfect Fit kit to tie the compressor and system together.

Richard swages lines and fittings...

Richard swages lines and fittings together to get our compressor on line.

The Restomod Shop is equipped...

The Restomod Shop is equipped to perform just about any restoration task, including refrigeration and hydraulic line fabrication.

The receiver tank is installed...

The receiver tank is installed with all lines and connections complete. This is the system pressure switch, which prevents system start-up when there’s not enough refrigerant.

Fan motor power is three different...

Fan motor power is three different resistances to ground via a three-position switch, which is exactly like the Mustang’s original switch. Where it differs is air-conditioning compressor clutch power via a micro switch activated by the factory heater control. The micro switch is closed mechanically, which gets power to the thermostatic switch at the evaporator. If temperature warrants, power then travels to the high/low pressure switch. If the high/low pressure switch is closed, the compressor will engage. Power must be switched and only when the ignition switch is on. It must also be fused.

This is the switched resistance...

This is the switched resistance to ground, which controls fan speed.

The Perfect Fit unit is anchored...

The Perfect Fit unit is anchored at the cowl as well as other locations. When you position the unit, these locations will speak for themselves. Use 3M Rope Caulk to prevent leaks.

Perfect Fit cables install...

Perfect Fit cables install a lot like the Mustang’s original cables. However, operation is smoother and adjustment simple.