Tinted windshield

[texasguy]

I live in Texas where it's pretty hot and I can vouch for the AC problems that have been reported.

First of all, a 4 cylinder engine is not going to cool as well as a 6, particularly at idle. Second, the CX-7 has a large windshield with a steep slope. That lets in a lot of heat. I have the black interior.

Needless to say, after sitting in the hot sun all day at my parking lot at work, this car was very hot and took a long time to cool down.

I went to my local tint dealer and got the front windows tinted. They had the latest solar blocking tint that really worked. It turns out they had one for the windshield, too. this has made all the difference for me. Make sure the tinter is a reputable one and has experience with doing windshields. technically it's illegal to tint your windshield, but I went with the lightest tint possible, so it's hardly noticeable. it does block a lot of heat and the AC has less work to do.

Another issue with the large windshield is that it's hard to find a sun shade that will match. I ended up buying one from the mazda dealer for $32.

So for anyone that has complaints about the AC, I highly recommend getting the best solar blocking window tint you can find and tinting the windshield as well. Sure they could have put in a heavier engine, but that would sacrifice the handling. It is frustrating that the sales people don't acknowledge it's a weaker AC - but common sense tells you it's not going to cool as good as a V-6 that has a box shaped windshield.

[IntegraRC]

it shouldnt matter between 4 and 6 cylinders because air conditioners are powered by the same 5-10 hp anyways. The only difference is that in an underpowered car, having 10 hp eaten up by an air conditioner may slow you down, but that does not mean the air conditioner is getting less power. If the air conditioner isnt good, it's probably more of the design of the air conditioner itself rather than if it gets its 10 hp from 4 or 6 cylinders. However, what you're saying about the huge windshield is true, and the black interior probably doesnt help.

[texasguy]

at idle speeds, a 4 cylinder power output can get as low as 40hp. at higher RPM's the cooling is the same for any car. it's no surprise that a 4 cylinder doesn't power as much at idle as a 6.

[IntegraRC]

it shouldn't matter if a 4 cyl only has 40 hp at idle. If an air conditioner requires only 10 hp max, then it's not being deprived of power. I am not arguing that a 4 cyl does not make as much power as a 6, but in this case it should not matter. If a tv required 100 watts and you are able to supply both a 100 W source or a 1000 W source, the tv will still only use 100 W either way.

[texasguy]

the engine also has to power the alternator, crankshaft, and whatever other electrical load it has. sure it can run with only 40hp, but everything is much happier when the rpm is higher. a lot of folks when they test drive are going to start a hot car and then sit there in idle while they look over all the controls - this is why you get reports that the AC is weak. plus there are other design factors that make a car hard to cool.

if you're still not convinced, go sit in a car at idle and compare the AC to when you rev the engine. this has to be done in a hot vehicle when the engine is first started. now a 6 has the same problem, but it can produce more hp at idle.

once at steady state, i agree it won't make a big difference whether its a 4 or a 6.

[IntegraRC]

It only "appears" like it's weak because when sitting still, the condenser coils in the air conditioner do not have wind blowing through them. In a sense, it's like trying to radiate heat into a metal box with a running engine inside...not efficient at all. When the car is actually moving, air can flow through allowing the heat to radiate out of the coils more efficiently. What you're talking about in revving the engine is that some cars have a fan that is related to the rpm of the engine which increases flow, but many cars now have electric fans anyways.

With everything being "happier" at high rpm might apply when actually driving the car, I do not agree that it applies when sitting still. 40 hp is something like 30,000 watts, so unless you're powering hundreds of lightbulbs, toasters ovens, or microwaves, the engine shouldn't be straining too much. As a matter of fact, the alternator would not even be able to convert that much power to electricity; many hybrid electric generators/motors can't even convert that much power!

[texasguy]

you can easily test it out for yourself the next time you start your car. all the facts you state are true. I'm just saying the car will cool better at higher rpm's regardless of whether it's moving or not and that, as a general rule, a 6 cylinder will cool better at idle than a 4.

the CX-7 uses an electric fan as do most japanese cars.