Michael T

On an 85 degree day after running the AC on the second fan speed with car moving for five minutes, what sort of center vent temperature do you get?

dr bob

In the dry L.A. climate, I could easily see 18ºF with fan on 2 after all the heat-soak heat is dissipated, with the freeze switch jumpered. Freezes fingers on the steering wheel on extended rides, to the point where I'd pull the freeze switch jumper when touring. Black car with no tinting, front system running only.

Humidity borrows pretty massive amounts of system capacity, and the amount of heat you need to pull out from sitting in the sun can also be massive. I'm not sure you'll find a fitzall performance number, especially considering the oppressive humidity that Houston enjoys once or twice a year... for months at a time it seems.

Michael T

Thank you for the response. I would be interested in other views, especially in high humidity.

SwedeInSiam

I don't know what temperature I get but the car gets freezing cold when I'm driving. And that's in Thailand's tropical climate with very high humidity (and a Midnight blue car).
The car have a fairly new compressor and running on R12 with disconnected heater hoses (no need in Thailand).
The AC system in my '80 928 is just as effective as in the modern Honda's I have.

griffiths

Michael,

Assuming a black shark as opposed to silver or white, and relative humidity levels noted by Doc Bob, I'd imagine you are going to find a range of vent temps. Add to the puzzle, the amount and intensity of sky sun light (clear day, overcast, early summer or mid summer)the angle of the sun, and how long the shark has been cooking out there.

Can't say I ever observed the vent temp at such an early point in the ac cool down process (only 5 minutes into the drive) on either of my past sharks; 1978, 1984s and 1989s4. The later also had dual air (two evaporators) which tends to raise the front center vent when the rear ac is turned on.

Most of the measurements we took were in this scenario, for example:
August in NJ
Shark cooks outside for 3 hours or more.
Noon to 3pm.
85-95F ambients
Relative humidity 30-60+%
1) Get in the toaster and open all windows and sunroof.
2) Start the beast.
3) Drive at least 2 minutes or more before turning on the AC
because mother nature at 85-95F can do a better job to suck
out 130F out of the cockpit.
4) Turn on AC to max cold and start to close up the windows when
vents feel colder than ambient.
5) Drive for 5 to more minutes and I'd say in all model years, running
R134a, rear off because its useless, the center vent range anywhere
from 32F to 38F easily. Sharks cool well.

In terms of a more important temperature,
I'd focus on something more relative to driver comfort,
say what is the temperature at the driver's head or chest level in the cockpit.

And, assume you are measuring apples and apples. Not comparing a vehicle that has a perfectly running AC system as opposed to one that has issues with the fresh air mix, under charged, etc.

Don Carter

Michael,

In Houston, running R12, I get about 42 in the center vent.

zekgb

After I did my R134 conversion this summer I had no problem bouncing the thermometer off the freeze switch at 38F with ambient at 100+ (but low NorCal humidity.)

FredR

At this time of year we typically see day time temps around the number you quote and RH 60% - sometimes more. The car is now kept in my garage and more or less straight away blows nice cold air running R134 [R12 was better] noting that I quickly get onto a good carriageway doing 75 mph [when I am a good boy]. I would estimate the centre vent temp to be around 5C and it can quickly make my fingers feel a bit uncomfortable running at anything but the lowest fan speeds.

Put the thing outside in our summer heat and it can take ages to cool down, especially so in traffic. By the way the best way to get rid of heat soak is to run with the windows open for a few minutes - over here at least static cabin temps can and do hit 80C if no shade.

Rgds

Fred