Would you trade your AC for some extra MPG??

[tjts1]

Originally Posted by jamesqf

Just a thought: for those who live in hot climates and use A/C regularly, why not look into adding more insulation to the passenger compartment? The roof, for instance, with just a cloth headliner & some sheet metal, has got to be a major heat source. Styrofoam insulation would weigh next to nothing...

Most of the radiant heat gets into the car through the windows, not the metal roof. Either way its a moot point when the outside air temp is 95f and you're sitting in stop and go traffic for a couple of hours on the 405 freeway. Trust me. You'll be crying for AC.

[Xringer]

Originally Posted by tjts1

Most of the radiant heat gets into the car through the windows, not the metal roof. Either way its a moot point when the outside air temp is 95f and you're sitting in stop and go traffic for a couple of hours on the 405 freeway. Trust me. You'll be crying for AC.

My last car had a black roof, and I could notice the heat coming off it sometimes at the end of the day.
I would park facing the setting sun and use a solar reflective sheet behind the windshield and keep the windows rolled down a few inches, so it never got super hot.. (Like in Texas w/ 209 deg steering wheels).


But, if I put my hand up on the head liner, I could feel the heat.

On a real sunny day, you could fry eggs on the top of that roof!

Silver cars are nice. My kid has a black BMW X3 and that thing is like a freaking oven inside during the summer..

[NiHaoMike]

Originally Posted by Xringer

Someone here has already added some pipe insulation on the AC tubing under his hood. IIRC, some of his AC pipes were getting frosted up..

Sounds like the evaporator coils are dirty, the expansion valve is bad, or the system is a little low on charge. None of the pipes in an A/C should ever get cold enough to frost, as it would indicate liquid return to the compressor.

[Xringer]

Maybe it was the low pressure side to the compressor??

[greenitup]

my a/c is broken (the air never gets cold) so the decision is easy for me in my truck.

[Xringer]

Originally Posted by greenitup

my a/c is broken (the air never gets cold) so the decision is easy for me in my truck.

How big is your compressor? Is it located up near the top of the engine?
Is it a good candidate adding a little electric assist?
(Meaning do you use it for making mostly short trips)?

[NiHaoMike]

Originally Posted by Xringer

Maybe it was the low pressure side to the compressor??

In A/C, the suction line should not get cold enough to ice up. It is normal for it to get wet, but if it frosts up, it indicates liquid in the line.

[Curly1]

Here in the United States of Texas air conditioning is mandatory not optional. Often it is over 100* outside and hotter than that in the cars. (maybe 125*?)

[Clev]

Originally Posted by jamesqf

Just a thought: for those who live in hot climates and use A/C regularly, why not look into adding more insulation to the passenger compartment? The roof, for instance, with just a cloth headliner & some sheet metal, has got to be a major heat source. Styrofoam insulation would weigh next to nothing...

I drove from Southern California to Phoenix and back this past weekend in a white exterior/light grey interior Buick Lacrosse. It is pretty heavily insulated and has some kind of coloring in the glass. In 96-99 degree weather, I was able to "P&G" the A/C compressor (keeping it on for 2 minutes, off for 8-10 minutes, with the switch set on recirculate and the fan blowing at med-high.) My dark blue Honda usually is 2 minutes on, 4 minutes off at that temperature. The trip back, with the sun at the driver's side window, was a bit worse--probably 2 minutes on, 6 minutes off. I averaged 33.6 mpg there and 32.6 mpg back with no P&G--not bad for a big 4-door with an auto and no P&G.