Window "tint" saves fuel through reduced AC load (duh, but nice to see quantified)

[Super22LL]

It's funny that I should see this two days after I tinted the windows in my S10. I did it because of the heat here on the Mississippi coast. Using the AC on my truck drags my FE down about 2 MPG. Since I have tinted the windows I am able to turn the AC off at times and still have the truck cabin cool enough to be comfortable. I "pulse and glide" it as mentioned by one of the previous posters. My next mod will be to identify which wire supplies power to the AC compressor and install a toggle switch on it. S10's do not have an on/off switch for the AC and I would like to be able to run the AC on "max cool" recirc mode with the compressor off recircing the cool air .

[Seek]

To get the most from this WOULD require setting up an a/c switch to turn on/off as necessary and it is true that most cars just adjust the hvac doors inside the dash. Even with it on 100% of the time though, there is some misinformation in this thread. The a/c compressors cycle on and off based on refrigerant pressure. Heat exchange is what causes refrigerant to switch between gas and liquid states, low and high pressure. When less heat is transferring into the evaporator in the vehicle cabin (due to less cabin heat), the pressures do not change/rise as much on the low pressure line as in a warmer cabin. This in turn requires the compressor clutch to cycle on less to retain the proper high and low pressure in the a/c system. Because it is a closed system that uses an orifice for phase change, pressures do even out between the low and low side with time so there are other variables involved but basically, you will save energy from the a/c compressor being engaged on less.

Noticeable at the pump, likely not at all.

[dremd]

cooling Load does affect A/C horsepower use; my dad had an 84 dodge 3500 van when I was a kid; when we painted the roof white not only did FE improve, but hill climbs were posable with cruise on (with A/C) that were not posable (without downshifts) on similar days before. I know poor data.

More data; my new central A/C draws ~2000 watts with the inside blower on low and ~4100 watts blower on 3 ton. (borrowed TED installed on exterior unit only).

In the TDI I can see a 3 hp difference (on sgII) when changing blower speeds from low to high (more pronounced with variable displacement compressor).