Cooling Your Vintage Vette - Part 3

Reach up behind the dash from the driver side, and pull the control switch and cable free. The duct hoses are also visible in this shot.

This is 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 glovebox 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 crossmember. The A/C thermostat switch is located just below the crossmember, behind the VIN plate, within convenient reach. Though it looks (and is) pretty busy in here, the glovebox 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 wires can be connected to the positive battery terminal or to the battery terminal on the starter solenoid (we opted for the solenoid terminal).

The circuit breaker is 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 are 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 sticky; moistening your fingers with dishwashing 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 pounds for a half hour to check for leaks. When we were satisfied the system was tight and leakproof, we charged the system with 1.8 pounds (28.8 ounces) 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.