Electric AC compressor?

[serialk11r]

Have you done everything you can to reduce heat in the cabin first? E.g. heater control valve doesn't leak any heat into the cabin, window film, maybe vinyl wrap the roof in silver/white (my dark gray car's roof gets insanely hot, I can feel the heat through the headliner).

[EcoCivic]

Originally Posted by serialk11r

Have you done everything you can to reduce heat in the cabin first? E.g. heater control valve doesn't leak any heat into the cabin, window film, maybe vinyl wrap the roof in silver/white (my dark gray car's roof gets insanely hot, I can feel the heat through the headliner).

I have taken a few simple and cheap steps to reduce heat such as sealing the firewall around wiring, throttle cable, clutch cylinder, etc and getting good window tint, both of which made a large enough difference to be worthwhile. Still need to replace my trunk weatherstripping, it's pretty badly torn up. The right side of the trunk gets pretty hot from the muffler, so wrapping the muffler in exhaust wrap would probably help too.

I need to figure out some type of heater control valve setup. Unfortunately the oil cooler/warmer I added complicates heater control because I installed it in series with the heater core and I need coolant to flow through the oil heat exchanger constantly without flowing through the heater core. For now I just bypass the heater core in the spring and reconnect it in the fall. Not a great solution, but it's effective.

I think sealing/insulating the cowl from the engine compartment as much as possible would be a big improvement too as the air blowing out of the vents has always been noticeably warmer than outside air if the AC isn't on even when the heater core is completely bypassed.

[ksa8907]

I agree with and would recommend going the route of reducing heat intrusion. Modifying the mechanics of the a/c system seems very time and money intensive. Reducing heat intrusion would mean less need to run the a/c and it would cycle off more.

[cRiPpLe_rOoStEr]

Reducing heat intrusion is a good point. On a sidenote, considering some motorcoaches are now fitted with an air-cycling setup more similar to what is found on modern airliners instead of the vapour-cycling more commonly fitted to cars, that's something I would be quite tempted to try.

[serialk11r]

Originally Posted by cRiPpLe_rOoStEr

Reducing heat intrusion is a good point. On a sidenote, considering some motorcoaches are now fitted with an air-cycling setup more similar to what is found on modern airliners instead of the vapour-cycling more commonly fitted to cars, that's something I would be quite tempted to try.

Air cycling? That sounds like it would be extremely loud in a car!

I think the OP has done pretty much everything reasonable to reduce heat intrusion. Cars just get hot and you gotta run the A/C I guess.

[cRiPpLe_rOoStEr]

Originally Posted by serialk11r

Air cycling? That sounds like it would be extremely loud in a car!

I would be more concerned about packaging.

[EcoCivic]

I think I figured out a large part of why the air coming out of the vents always feels much warmer than outside air or cabin air- half of the HVAC system's fresh air intake is under the freaking hood! I can't believe I just noticed that. As a test I taped over the under hood part of the wiper cowl to see if that makes a difference. The airflow does seem to be slightly less in fresh air mode with the under hood vent covered, but that should be easy enough to fix by enlarging the vent openings by the wipers and covering the openings with some type of screen to keep crap out.

The other thing I noticed is that even with recirculate on (and it usually is), there is still some air being pulled in through the exterior fresh air intakes. I also notice that some outside air gets forced in through the vents when driving down the highway with the blower off. I'm not sure if that's normal, I would think it should be blocked off. But my blend doors are slightly screwed up, so I wouldn't be surprised if that has something to do with it.

[Ecky]

Originally Posted by EcoCivic

The other thing I noticed is that even with recirculate on (and it usually is), there is still some air being pulled in through the exterior fresh air intakes. I also notice that some outside air gets forced in through the vents when driving down the highway with the blower off. I'm not sure if that's normal, I would think it should be blocked off. But my blend doors are slightly screwed up, so I wouldn't be surprised if that has something to do with it.

That happens in my car as well unless I turn on recirculate.

[Hersbird]

Just running your a/c is the least expensive solution by a factor of 100 I bet. What exactly do you mean kills your MPG? Going from say 40 to 35 isn't that big of a deal. Maybe $100-$200 a year. However you charge the battery will take some energy too. If you really want to get 40+ and run your A/C just buy a used Prius for probably less than any wierd conversion would cost. Plus I bet adding 300 pounds of battery might also hurt your MPG similar to running the A/C on the belt.

[EcoCivic]

Originally Posted by Ecky

That happens in my car as well unless I turn on recirculate.

Thanks. If I turn on recirculate the outside air doesn't stop entering the cabin. It stops coming out of the vents; instead it comes out of the interior air intake for recirculate behind the glovebox.