Just wondering...is it normal that the air conditioning kicks in whenever you switch to defrost mode on the front windscreen? It seems kind of odd, that this happens regardless of the outside temperature. But what do I know?

 

The reason is that you don't want humid air going onto something that is already fogged due to humidity. The AC turns on to deliver "dry" air so that the windows will defog faster. And it indeed works. Once the window has defogged I would turn off the air and see if the window stays clear. Most likely it will fog up because there is too much moisture being blown onto the window. If it stays clear keep the AC off.

So you can defrost using ac or turn ac off and it will still defrost the windows.

 

The A/C helps to "dry" the air and in a defrost mode that is exactly what you want to have happen - I have read here that some prefer not to use the A/C to defrost, but I don't really care because I would rather have the defrost work as designed...

 

Out here with Mississippi humidity, I have yet to find a happy medium on how to best use the HVAC system. Also, on very humid days, the AC does not cool as well. I only have problems on VERY humid mornings, and even in the BMW and the wifes car, same problems....just nature, nothing I can do about it.

 

Most cars (including my previous Maximas) turn on the AC whenever the defrost is turned on, as nothing defogs better than DRY air.

The only complaint I have is that, once I turn off the defrost, the AC compressor continues to run, even if I turn off all HVAC functions, until I actually turn the ignition off. The driver's manual confirms this is the way the system operates, but . . .

 

I'm still trying to get used to this, and this time of year it's the worst around here (NYC area). It's not cold enough outside at night to have the heat on, but it's not warm enough to use the AC... but the windows fog up during the 50-60° that we see at night. So you kind of end up with AC during the day and then kick up the temp at night if you want to use the defroster.

What I would have liked was a "full blast" high heat defroster... hit the button and the thing literally thinks your car is frozen solid. That's what I get on my other car (more of a "de-icer" ) and it works exceptionally well -- especially in the winter time.

Oh well... I guess that's the breaks though.

 

So as soon as the compressor is engaged either by AC or for defrost, the compressor continues to run regardless of HVAC controls until the vehicle is actually turned off. Damn thats just silly. I'll use AC or defrost for a bit and then shut it down to conserve fuel. Guess I was just fooling myself. Grrr.

CM.

 

You might be surprised at how little difference is made in your gas milage by running your AC. Studies have shown that AC units in today's cars are so efficient that it causes no more stress on your engine than drag caused by driving with your windows down.

 

That might be so, but I think the point some people argue is that when you close your windows, they stay closed. With the AC, even when you turn it off, the compressor is still going... kinda like your windows being cracked even after you "closed" them...

I can see the benefit though... not having to start/stop the whole system cuts back on wear and tear. I for one some times start it up, then kill it later only to start it up again later on in the trip, so I suppose it makes sense.

 

Yeahn what he said. And its TRUE!

(BTW, do you notice a film on the inside of the windshield? Like an oil? i thought my windshield was getting dirty, but it was the inside. I don't smoke. And someone told me its normal as the AC produces this. And humidity condenses on the inside (even if the AC dries it) and attracts dust and airduct particles. So when does one replace the vent air filter?)

 

I notice it too! I guess it's not just me. Thanks for the explanation.

 

Yep, I have the same thing on the inside of the window. This car has it more noticable than any other I have owned. Looks like I have been smoking in the car after a week.

 

So if the compressor never turns off, then why bother turning the A/C off? Just leave it running all the time, since Nissan seems to thing it does nothing for the fule economy. Unfortunately in my 2000 Max, I feel a huge power loss when turning the A/C on and I rarely use it. Hope this is not the case with the 04/05's?

 

I have not noticed any power loss when running the AC, but my butt is not very sensative and I haven't had it calibrated lately Also I have to admit, if challenged at a stop light by a car I think might give me a run for my money, I'll turn the AC off, just to be sure.

 

I can feel a small difference when switching the AC on and off. Most newer car though.....well at least my Z28 with the LS1, at wide open throttle, the compressor will shut down. Not sure on the Maxima, but sure on WOT, the Maxima does the same. If I remember, it is a safe mode for the AC. Anyone have any info on this?