Thread: Aftermarket A/C - Blows cold, but doesnt cool off the car

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I'll add a few things to what Bill said.

What is the condition of your door seals? Air leaks will have a big affect on cooling.

What is the color of the car? Dark colors will add a lot of extra heat.

Does it start out blowing a lot of cold air and then drop off? The evaporator can freeze up when the charge is not quite right. Also, most of the aftermarket manufacturers I have seen do not recommend setting the thermostat to max cold to prevent the coil from icing over.

How much insulation is in the car? Older cars usually don't have much if any. Just the firewall can radiate a lot of heat that the AC has to deal with. This goes with what Bill said about the inlet temp of the air to the unit. If it's near the firewall, it could be having to cool very hot air.

How big is the condenser? If it was originally an R12 unit that has been converted to 134A, the condenser may be too small to reject all the heat. It was learned early when 134A started being used that the condenser needed to be at least 20% larger and/or much more efficient to get rid of the heat in the refrigerant. Look at new cars. They have very efficient cross flow condensers.

If it was an R12 unit that has been converted to 134A, the expansion valve should have been changed out for the higher pressure refrigerant.

How far is the condenser from the radiator? It needs to be spaced off the radiator about 1/2" to 1". No more. Too close and it picks up heat form the rad, too far away and it becomes a flow restriction for the whole cooling system.

I feel your pain, too. The Airtique(spelling?) AC in my black 46 coupe will just barely keep you from sweltering in really hot weather. The dark color and less than great insulation, as well as a weak AC unit are the culprits, I think. Will be getting the largest Vintage Air unit I can fit when I redo car. Along with lots of insulation.