Factory air conditioning system performance

[Milsteads Garage]

I install vintage air systems on stuff like Camaros Mustangs and Broncos. I’ve never installed one on a Mark II and that’s because even though the evaporator box is small, there is no good place to install it under the dash without seeing the box. Another thing you are going to have to do is mix and match parts to get it to work. They might have a bracket kit that bolts to a 460 but maybe not.

[Barry Wolk]

If you have an early car with intakes on the rear fenders the A/C is pretty terrible. That's why the vents went away. Elmer Rohn designed a work-around that eliminated the intakes and ran a tube through the rocker cover with flex pipe on each end to feed fresh air to the trunk unit. Morgan's right, there's no room under the dash.

[Don Henschel]

The evaporator unit within the trunk is anything but small. The Frigidaire compressor is up to the task but you cannot leave the compressor continuously running without some sort of a way to control the temperature of the evaporator. If it gets too cold and you don't have a throttling valve for recirculation TO REDUCE THE FLOW TO EVAPORATOR your evaporator can get too cold and if you turn the blowers to low it can and will start to ice up on the outside due to freezing condensation. This causes the low side pressure to get extremely low as well. Modern vehicles have a cycling switch that senses low pressure which occures when your evaporator gets cold and shuts the compressor off allowing the evaporator too not only warm up but also defrost as well and as the evaporator warms up the pressure rises and click, the cycling switch turns the compressor back on. Of course not only have they eliminated the thermostat using the cycling switch, they use an air blend door to allow warmer air to mix with the cooled air if you want to control the air temperature. YOU NEED BOTH!! My suggestion is look for a newer Mercury Marquis or Lincoln with a throttling control valve that was used with the Frigidaire compressor or attempt to use your Mark II throttling valve by getting hoses made up to connect it to your Frigidaire compressor. Since somebody decided to install a 460 under the hood means you will now have to figure out how to make this creation of a mongrel work!! There was an obvious reason why they used the throttling valve instead of a thermostat switch when your evaporator is in the trunk. How do you reach over and adjust a thermostat that has the sensing probe inserted into the evaporator fins when it's located in the trunk? An evaporator under the dash can easily have a thermostat switch but there is no room for one along with the blowers on the Mark II and is why it was located behind the seat.
Is creation of these mongrels such a good idea??

[Don Henschel]

If you have an early car with intakes on the rear fenders the A/C is pretty terrible. That's why the vents went away. Elmer Rohn designed a work-around that eliminated the intakes and ran a tube through the rocker cover with flex pipe on each end to feed fresh air to the trunk unit. Morgan's right, there's no room under the dash.

And it is totally beyond me why anybody thinks installing these stupid "nostrils" is such a great idea?? Cooling was lousy and when driving in rain, the wind driven rain gets forced into them as well.