A stock Mustang in summer is a test of endurance. The factory heater barely works. Factory A/C, if your car even has it, uses R-12 refrigerant (illegal to buy, impossible to recharge) through a system designed when "adequate cooling" meant "not dying." Modern drivers expect modern comfort.
Vintage Air's Gen IV SureFit system is the correct solution. It's engineered specifically for the 1967–68 Mustang, uses modern R-134a refrigerant, puts out genuine cold air, and installs without cutting the firewall or modifying factory sheet metal. This guide walks through the complete installation.
Most aftermarket A/C kits require cutting and welding. Vintage Air SureFit kits use application-specific mounting brackets and pre-formed hoses that follow factory routing paths. Everything fits where it's supposed to go. No fabrication required.
The Gen IV Magnum evaporator is significantly more efficient than older Gen II systems. It moves more air volume at lower fan speeds, which means quieter operation and better cooling in stop-and-go traffic where heat soak is worst.
System capacity: The Gen IV system is rated at 40,000 BTU/hr — enough to cool a full-size SUV. In a Mustang's small cabin, it will get uncomfortably cold at anything above half fan speed on a hot day. That's a good problem to have.
The Vintage Air PN 961380 SureFit kit for 1967–68 Mustang includes:
- Gen IV Magnum evaporator assembly with built-in heater core - Sanden SD508 compressor with mounting bracket - Parallel-flow aluminum condenser (20" x 24") - Receiver-drier assembly - All refrigerant hoses (pre-formed, #6 and #8 barrier hose) - Expansion valve - Wiring harness with relay - Control panel (temperature and fan speed) - Dash vents (round, fits factory openings) - Vent ducting - All mounting hardware, firewall grommets, and templates
What you supply: refrigerant (2.5 lbs R-134a), installation labor, and someone to vacuum and charge the system.
Mechanical tools: - Floor jack and 2 jack stands - 3/8" and 1/4" drive ratchets, standard and metric sockets - Set of combination wrenches (8mm through 19mm) - Two sets of #6 and #8 AC line wrenches (one to hold, one to tighten) - Step drill bit set (for firewall penetrations) - Hole saw set (2.5" for refrigerant line grommets) - Wire fish tape for pulling wires through firewall - Rubber mallet - Torque wrench
Electrical tools: - Multimeter - Wire stripper/crimper - Solderless connectors (butt splices, ring terminals) - Heat shrink tubing
Refrigerant tools (if DIY charging): - 4-valve AC manifold gauge set - Vacuum pump (3 CFM minimum) - R-134a service port adapters - 2–3 cans of R-134a (12 oz each, system takes ~2.5 lbs total)
Before you open the kit box, spend 30 minutes in the engine bay.
Cooling system check: The condenser mounts in front of the radiator. Adding a condenser reduces airflow to the radiator by 15–20%. If your cooling system runs warm now, it will run hot with the condenser in place. Address this first: new thermostat, flush the system, and verify the electric fan is moving adequate CFM. Vintage Air recommends a 2,500 CFM electric puller fan mounted behind the radiator.
Belt routing: The SD508 compressor adds roughly 5–7 horsepower of parasitic load when engaged. Verify your accessory belt is in good condition and the belt routing is clear of the new compressor mounting location.
Power steering clearance: The SureFit kit's compressor bracket is designed to coexist with factory power steering. Verify your power steering pump and bracket are stock — aftermarket setups sometimes conflict.
Remove the glovebox. This is three screws and a friction fit on the 1967–68 Mustang — takes five minutes.
The evaporator assembly mounts under the passenger side dash using three bolts through the toe board. The kit includes a paper template for drilling these holes. Tape the template in position, confirm it's level, and drill 5/16" holes.
The evaporator has two refrigerant fittings that penetrate the firewall. Using the included template, mark and drill two 2.5" holes in the firewall. The holes land in the factory-blank area below the A/C delete plate. Install the rubber firewall grommets included in the kit — they protect the refrigerant lines from chafing and seal against engine compartment fumes.
Don't tighten the evaporator mounting bolts until you've positioned the refrigerant lines and verified they route cleanly through the firewall holes. Once the lines are through the firewall, bolt the evaporator in place from underneath.
The condenser mounts in front of the radiator using four brackets that bolt to the radiator support. The kit includes a cardboard template for positioning. The condenser sits approximately 1" in front of the radiator core. Drill four 5/16" holes in the radiator support per the template.
With the condenser bolted in, verify the hood closes and the fan shroud doesn't contact the condenser. Turn the steering lock-to-lock and verify nothing contacts the condenser through the fan path.
Install the receiver-drier on the passenger side of the engine bay using the included bracket. The receiver-drier goes on the high-pressure (liquid) line between the condenser and the expansion valve. Position it vertically with the sight glass facing you.
The SD508 compressor uses a bracket that bolts to the driver's side of the small block using the existing accessory mounting holes. The kit is specific to small block Ford (221/260/289/302). If you have a big block or non-factory engine, contact Vintage Air tech support before ordering.
Install the bracket with the supplied hardware. The compressor body should sit with the oil fill plug accessible and the clutch coil facing forward for wire access.
Measure the required belt length with the compressor in final position before ordering — the distance varies based on whether you have power steering and alternator positioning.
The SureFit kit includes pre-formed hose assemblies that follow the 1967–68 Mustang's factory routing paths. Route them as the instructions show — don't force a hose to a shorter path. The pre-formed bends exist for clearance reasons.
Line connections: - Compressor to condenser: high-pressure discharge line (#8 hose) - Condenser to receiver-drier: high-pressure liquid line (#6 hose) - Receiver-drier to evaporator (expansion valve): high-pressure liquid line (#6 hose) - Evaporator to compressor: low-pressure suction line (#8 hose)
All connections use O-ring face seal (ORFS) fittings. Install new O-rings (included) and lubricate lightly with refrigerant oil before assembly. Use two wrenches at every connection — one to hold the body, one to tighten the nut. Torque #6 fittings to 12 ft-lbs, #8 fittings to 18 ft-lbs. Finger-tight plus 1/4 turn is not adequate. Under-torqued ORFS connections leak refrigerant immediately.
The Vintage Air wiring harness is color-coded and labeled. The system has three circuits:
Compressor clutch: Switched 12V through the included relay. Run the relay ground to a chassis bolt with good paint-free contact. Run the relay power from the fuse box on a dedicated 15A fused circuit.
Blower motor: Variable voltage from the control panel's blower speed switch. The motor draws 8–12A at high speed — use 14 AWG minimum for this circuit.
Control panel: 12V ignition-switched power from the fuse box (10A fuse). The panel needs constant ground to chassis.
Route all wires through existing firewall grommets where possible. Seal any gaps with silicone to prevent exhaust fumes from entering the cabin.
Verify before proceeding: with ignition on and A/C switch engaged, you should have 12V at the compressor clutch wire (at the relay output). If not, trace the control panel wiring before charging the system.
The kit includes four 2.5" round dash vents that fit the factory defroster and A/C vent openings. Route duct from the evaporator to each dash vent. Keep ducts as short and straight as possible — every 90-degree bend reduces airflow by approximately 15%. Use the included duct clamps at each connection.
Install the control panel in the factory heater control opening or the center console depending on your preference. The Gen IV panel has separate controls for temperature blend and fan speed.
This step requires proper equipment. The refrigerant system must be evacuated to remove all air and moisture before charging. Moisture in the system reacts with R-134a to form hydrofluoric acid that destroys the compressor and expansion valve.
Connect your manifold gauge set to the system's service ports (high and low pressure). Pull vacuum with the vacuum pump for a minimum of 45 minutes with a 3 CFM pump. The low-pressure gauge should hold at 29 inches Hg vacuum.
Vacuum hold test: close the manifold valves and shut off the pump. Wait 15 minutes. If the vacuum holds (gauge doesn't move more than 1" Hg), the system has no leaks. If vacuum rises, you have a leak — find it before charging.
With vacuum confirmed, charge with R-134a. The 1967–68 Mustang SureFit system takes approximately 2.25–2.5 lbs (36–40 oz) of R-134a. Charge on the low-pressure side with the system running and the A/C on max.
Target operating pressures at 90°F ambient: low side 28–38 psi, high side 200–250 psi. Vent temperature at the dash should reach 38–45°F within 5 minutes of startup.
Once the system is charged and confirmed operating:
1. Run the car at idle for 30 minutes with A/C on max. Check all refrigerant line connections for oil staining (indicates a leak). 2. Verify the condenser fan (if electric) cycles on when compressor engages. 3. Check that blower speed control gives linear speed increase from low to high. 4. Measure vent temperature with a thermometer — 38–45°F at max cool in moderate ambient conditions.
System doesn't cool (compressor not engaging): Check voltage at clutch coil. If no voltage, check the relay — test by applying 12V directly to the relay trigger terminal. If relay clicks and clutch still doesn't engage, check the low-pressure cutoff switch on the receiver-drier.
System cools initially then fades: Low refrigerant charge or a restriction in the system. Check the sight glass on the receiver-drier — bubbles indicate low charge.
Blower motor runs but no cold air: Compressor is probably not engaging. Verify clutch operation. Alternatively, verify the expansion valve is in the correct orientation — installing it backwards is a common error.
Water dripping inside car: The evaporator drain line is kinked or clogged. The evaporator produces several ounces of condensate per hour in humid conditions. This drains through a rubber drain tube that exits through the firewall — verify it's clear and routed downward.
- Vintage Air Gen IV SureFit kit: ~$2,200 - Vacuum pump kit: ~$150 - R-134a refrigerant (4 cans): ~$40 - Step drill bits: ~$25 - Wiring supplies: ~$30 - Professional vacuum/charge (if not DIY): ~$150
Total parts: approximately $2,445. Professional shop charge for vacuum and charging adds $100–$150.
This is the most complex install covered in these guides. Plan for a full weekend. Have an extra day in reserve for unexpected issues. The payoff is a classic car you can actually drive in summer without melting. Your passengers will thank you.
The investment is approximately $2,400 in parts plus 20–25 hours of installation time. A properly climate-controlled Mustang gets driven more, shown more, and enjoyed more than one that sits in the garage from June through September.
Do this install once. Do it correctly. Enjoy it for the next 20 years.
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