1985-1998 [Subscribe to Daily Digest] |
I have been riding around with a thermometer in the center vent for the past 3 summers. My conclusion is that performance is too variable to quantify because cool down is so heavily influenced by the inside temperature of the car and humidity.
Remember that ac does not put cool air in the car, it sucks the heat out. Therefore, when the inside temperature of the car is 140F, it will take some time to cool down. Even the heat absorbed by the seats and plastic interior parts has to be sucked out. One thing I do when it's really hot is to drive with all windows open for 5 minutes or so. The reduces the air temperature in the car to the outside air temperature which is often 20-40 degrees (f) cooler than the interior of the car. The helps speed cool down since cooling from 100 (f) is a lot easier than from 140(f). In fact, if you watch the recirculation function of the ACC, it does not come on until after a couple of minutes. This is an attempt to bring cooler air into the car from outside before trying to really cool.
In my experience the factory r134a cars cool down faster than r12 cars which were converted. However, 1992 is a possible exception to this rule since it had many of the r134a parts, including the block type expansion valve.
Generally, I expect to see an ultimate vent temperature of 48-50 (f) before the ac compressor starts cycling. 45F is doing really well for a converted car and may be a function of the ACC software, being a 1992 model year or window tinting. I will sometimes see 45F on a hot night, but that is rare. As I said, usually the compressor will cycle off at 48 (f). The time it takes to get to the ultimate vent temp really depends on how hot the inside of the car is, as much as on the outside air temperature. For instance, on a cloudy 95 degree day, the car can sometimes cool faster than on an 80 degree sunny day since the inside of the car gets much hotter in the sun even though the air temperature is less. I would say that on average, with an interior temp of more than 110F but less than 130F, I can get to the lowest vent temp within 10-15 minutes if I start with the windows open for a few minutes.
posted by 24.50.58...
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