by Tom Benford
I wanted to install air conditioning in my 1967 big block Corvette coupe but, since this is a numbers-matching car, I didn't want to cannibalize the interior or engine compartment to do it. Vintage Air had the solution I was looking for: a custom-made air conditioning system that was very close in appearance and fit to the original GM factory air that was offered as an option in 1967. I particularly liked the fact that it was a "non-invasive" system that could be uninstalled if some future owner of this car wanted to put it back to its original condition (of course, I'm keeping all of the original parts for this eventuality). Vintage Air has a network of dealers nationwide who will install their A/C systems for you, and this is probably the best way to go if you're not a skilled mechanic. As with most other Corvette projects, the working quarters are quite cramped and often difficult to access. For that reason, lots of patience, sweat and persistence are essential ingredients of an installation like this one. Now that the caveats are out of the way, here's how to proceed.
These are the interior components of Vintage Air's air conditioning system for Mid-Year Corvettes (the company also makes direct-fit systems for C1s and C3s). New side console ducts are provided, along with a new defroster duct; the under-dash ducts look and operate like factory originals. All components are clearly labeled and the instructions are clear and well illustrated. The only items not supplied with the kit are replacement heater hoses, the compressor belt and the 134a refrigerant.
The glove box is removed as the first installation step. Save the Philips screws, since they'll be required for re-securing the glove box at the end of the installation.
The side-panel vent knobs are removed by loosening the set screw, and then removing the cable-retaining nut allows the control cable to be freed from each panel.
All control-cable clips are removed from the OEM heater box, as well as the bolt that goes through the firewall to secure the unit. The wiring harness plug is also removed from the blower motor at this time.
A long-bladed screwdriver is used to loosen the hose clamps on the heater inlet and outlet hoses. Be sure to use a suitable container to catch the coolant that evacuates the system when the hoses are pulled. Precautions are in order, since antifreeze is toxic to household pets.
The factory heater box cover can be removed after disconnecting the harness connector and ground wire attached to it in the engine compartment. Once the cover is removed, the hoses can be disconnected from the heater core as well.
Here's the heater core with the box cover removed.
From the engine compartment, this is what you'll see after the heater box and squirrel-cage fan have been removed.
The Vintage Air unit contains the A/C evaporator as well as the heater core and fan. It sandwiches between the firewall and the dashboard cross-member.
Here's the evaporator sub-case in position prior to attaching duct hosing and making wiring connections. A bolt through the OEM hole in the firewall secures the rear of the case, while one of the lower glove box retaining bolts supports the front of the case via a bracket.
The duct hosing must be cut to specific lengths: the 2-1/2" hosing is cut to an 18" length for the driver's side duct and a 56" length for the passenger side; the 2" hosing is cut to 16" for the driver's console duct and 8" for the passenger console. The defroster duct uses an 8" length of 2-1/2" hosing.
The cut hoses are attached to the sub-case outlets and routed to their respective ducts, being careful to avoid kinks and squeezes that will restrict air flow. The passenger's duct is attached to the lower blower housing and the kick panels with self-tapping screws.
The driver's side duct is secured to the kick panel and with a supplied bracket to the underside of the steering column. Depending on your year, it may be necessary to relocate the headlight motor activation switch and/or the hood release. We lucked-out with the '67 and didn't have to move either one.
Here are the under-hood components of the Vintage Air A/C system. The compressor is a Sanden unit, and all hoses, fittings and O-rings are specifically designed for 134a refrigerant.
It's necessary to remove the hood to gain access to the front of the radiator to install the condenser and drier. It's a good idea to scribe or mark the hinge positions before removing the hood to simplify realigning it when you put it back on later. Remove the 3 bolts on each hinge bracket as well as the two bolts securing the hood support. This is not a one-person job — have a helper support the opposite end so you don't damage the hood.
The old heater hoses are the next items to be replaced. Again, a long-bladed screwdriver is used to loosen the hose clamps.
It's necessary to replace the original 3/4" hose fitting (left) on the big block with a 3/4-to-5/8" fitting, since both intake and outlet hoses are 5/8" on the Vintage Air unit.
A vacuum-operated heater valve is inserted in the heater hose and controls the flow of hot water into the core. The small-diameter hose that controls the valve connects to the intake manifold vacuum line via a "T" fitting inserted into the distributor vacuum line.
Three bare-steel brackets are supplied for mounting the compressor. To forestall rust, we gave them a coat of black POR-15 rust-preventative paint before mounting them.
Lower and upper condenser brackets are attached to the condenser using the supplied bolts.
The fresh air cover is installed on the passenger-side firewall under the fender to cover the hole formally occupied by the OEM squirrel-cage fan.
The two lower OEM bolts from the bottom of the radiator support rods are loosened enough so that the two condenser brackets can slide down on them; the two OEM bolts from the front side of the radiator support are used to secure the upper condenser bracket.
The drier is attached to the passenger side of the condenser using the supplied mounting brackets.
O-rings are used for all A/C connections, and the supplied tube of refrigeration oil ensures an air-tight seal for these connections. This is a very important detail to prevent refrigerant leakage.
This shot shows the condenser with attached drier in place in front of the radiator.
The upper condenser #8 hardline which goes to the compressor is installed next, followed by the #6 hardline from the drier through the core support.
A supplied 3/8"x2-1/4" bolt secures the front bracket, with a 1/4" spacer between the bracket and the water pump flange.
The second compressor mounting bracket is attached using a 7/16"x2-3/4" bolt that runs through the front bracket, through a 1-3/4" spacer and into the head.
The compressor adjusting bracket attached to the compressor using three 3/8" bolts with nylock nuts. The compressor is then attached to the mounting brackets with the supplied bolts and nylock nuts.
Here's a view of the mounted compressor prior to making any electrical or refrigeration connections and before the belt was mounted.
The instructions advise that a 61-62" belt will work. We found that a 61" belt was ideal and we adjusted the tension on the alternator belt after the compressor belt was mounted and tensioned.
Back inside the passenger compartment it was time to finalize the electrical connections. This purple wire is the key-on power lead that connects to a 5-amp fused source, in this case, the radio fuse. The red wire is a short 'jumper' connection, as the purple wire was a couple of inches shorter than needed to reach the fuse panel.
All of the white leads (3 in total) on the Vintage Air harnesses are grounds. We found one of the windshield wiper mounting lugs to be a good ground.
A second ground was also attached to the wiper lug. The third ground, coming from the blower motor control switch, had to be attached to the dashboard cross-member since the length of the wire was too short to use the wiper lug.
The lead from the A/C microswitch connects to the binary-type compressor safety switch. This connection is important, since it prevents the compressor from engaging or disengages it in the event of extreme low pressure (refrigerant loss) or excessively high head pressure (380 lbs.) to prevent compressor damage or hose rupture. The A/C system relies on refrigerant to carry lubrication through the system.
Here's a shot of the compressor with all hoses attached and electrical connections made under the hood. The system is evacuated and charged using the red- and black-capped valves on the engine-side of the compressor.
The existing OEM fan control switch is used. The first step is to remove the knob's set screw using a 5/64" allen wrench.
A spanner wrench is the used to remove the control retaining nut. If you don't have a spanner this size, a pair of needle-nose pliers will suffice.
By reaching up behind the dash from the driver's side you can pull the control switch and cable free. The duct hoses are also visible in this shot.
Here's a better look at the control switch with the new harness wiring in place prior to reinstalling it back in the dash.
Here's a view of the passenger side glove box cavity. The two black rectangular boxes with the wiring harnesses attached are relays for the system; one is the power relay (with the heavy red wire) and the other is the high blower relay. Note the third white ground wire connected to the center portion of the dash cross-member. The A/C thermostat switch is located just below the cross-member behind the VIN plate within convenient reach. Though it looks (and is) pretty busy in here, the glove box still mounts without a problem.
The heavy red lead from the power relay is connected to a 30-amp circuit breaker, shown here. The eyelet end of the wire connects to the positive battery terminal or to the battery terminal on the starter solenoid.
The circuit breaker was secured to the lower part of the firewall with two short self-tapping screws after connecting it to the positive side of the starter solenoid. Cable ties were used throughout the installation to keep both the wiring and hoses tidy.
The metal fittings of the suction line at the evaporator and the expansion valve are wrapped with insulating press tape. This stuff is very sticky, so moistening your fingers with some dish washing liquid makes handling it a bit easier.
The hose cover is secured to the firewall using the supplied nuts and bolts in the original OEM holes that previously retained the heater box cover.
A suction pump is used to evacuate the system for 35-45 minutes at a temperature of at least 85 degrees. On a cooler day the components can be heated with a hair dryer or by running the engine with the heater on before evacuating.
We pulled and maintained a vacuum of -28 lbs. for a half hour to check for leaks. When we were satisfied the system was tight and leak-proof, we charged the system with 1.8 lbs. (28.8 oz.) of 134a refrigerant, using a digital scale to get the weight exact.
Here's the completed installation, all charged and ready to enjoy.
The proof is in the pudding and, as this digital thermometer shows, the pudding is comfortably chilled at 57.9 degrees. The reading was taken from the driver's console vent while idling. At higher revs the temperature gets a couple of degrees colder.
Here's how the controls operate:
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