Disable A/C in defrost?

[saskdiesel]

Originally Posted by John_H

By "defrost" this owner is referring to "turning the upper vents on" which - it turns out - appears to run the A/C. I want the option to turn A/C on myself if the windshield doesn't clear quickly. Heated outside air in cool weather is superb at clearing a windshield; under some conditions, I'll turn the A/C on in my car that doesn't think for me. Personally, I just like to move the stale air out of the window area - it helps make a warm car feel cooler without A/C (unless the A/C is on anyway even though I want it off).

Yes!
And when there is cold dew on the outside of the window that smears when you wipe it.
I like the heat coming out with no need to run the AC compressor as I don't need any humidity taken out of the air.
Cars never used to be like this. And I wonder why they went this route.

[saronian]

I agree with saskdiesel, there are good advantages having all the airflow directed to the windshield, but not often is the AC required. It would be something I would want to disable.

[mdfortwoguy]

If you get cold dew on the outside of the windshield, move the temperature selector up a bit...

Have you ever tried to defog a window on a rainy day without A/C? It's damn near impossible without baking yourself in the car, and then the humidity causes the other windows to fog up.

[Maxwell/GA]

There's another reason for running the compressor in the defrost mode. If the compressor sat idle all winter long in colder climates, the seals in the compressor would dry out from lack of use and the freon would leak out. When the compressor runs, oil is distributed throughout the compressor.

[John_H]

I'm confused by some of these responses. WHY does the care have to do the thinking FOR me?! Why can't *I* have the option of running my A/C to help the defrost when I want to?!

Why not deliver all the claimed benefits of running the AC in defrost simply by cranking the AC on automatically whenever it's humid? Or perhaps whenever the driver makes a right hand turn? The selection of turning on the AC during defrost SHOULD BE under driver control and users should be educated that humidity can be knocked down immediately by hitting the A/C.

THis is a car that's trying to be frugal with gas but if the car forces the gas-hogging AC during the simple act of blowing air on the window, we're screwed.

[a2jack]

Originally Posted by Maxwell/GA

There's another reason for running the compressor in the defrost mode. If the compressor sat idle all winter long in colder climates, the seals in the compressor would dry out from lack of use and the freon would leak out. When the compressor runs, oil is distributed throughout the compressor.

Maxwell is right. The auto mfg's did not build in the AC/Defrost mode to make your windows happy, it's there to lube the AC system.

The Smart ACs have a poor track record and I think, like the Canadians, we can expect a trip to the dealers each Spring to refill the R-134. ($100 +). A2Jack.

[saskdiesel]

Originally Posted by a2jack

Maxwell is right. The auto mfg's did not build in the AC/Defrost mode to make your windows happy, it's there to lube the AC system.

The Smart ACs have a poor track record and I think, like the Canadians, we can expect a trip to the dealers each Spring to refill the R-134. ($100 +). A2Jack.

As a mechanic I say bull to this.
In the cold winter months the pressure switch will not let the compressor kick in. Even if you push the button the AC is not going to cut in in cold temps. My Ford truck is 8 years old and every year the AC works fine.
This is a mandated safety thing and I will figure this out when I get my CDI.
And all the Smarts I know have AC trouble every year but some believe its a series of o-rings that can't keep a good seal. Others think its the vibration of the diesel.

[saskdiesel]

Originally Posted by mdfortwoguy

If you get cold dew on the outside of the windshield, move the temperature selector up a bit...

Have you ever tried to defog a window on a rainy day without A/C? It's damn near impossible without baking yourself in the car, and then the humidity causes the other windows to fog up.

Your right.
But I can surely push the button if I need to dehumidify!
Last night I drove home at 1AM with the defrost/floor position selected in my Fit. I had heat on the windshield and my feet. Nice.
It was +7C.
And since I disconnected this "feature", the compressor doesn't cut in.
Maybe its just a Canadian thing.............

[a2jack]

Saskdiesel. I have been following this issue over a year on CsC.

To update. The service manager of Smart Bloomfield MI. specifically told me the new 451's do have the AC linked to the defrost mode.

Your CDI's do have a thermo cut off to not allow the compressor to engage below a set outside temp. According to the Smart SM this has been changed for NA451.

I see no reason to believe the "Gaser" will be less prone to leaks, as the AC line runs are just as long. No one knows how the NA451's AC will perform until a couple of years go by.

I am picking up a couple of cans of "Duracool" at Canadian Tire this week end...Just in case. A2Jack.

[saskdiesel]

Originally Posted by a2jack

Saskdiesel. I have been following this issue over a year on CsC.

To update. The service manager of Smart Bloomfield MI. specifically told me the new 451's do have the AC linked to the defrost mode.

Your CDI's do have a thermo cut off to not allow the compressor to engage below a set outside temp. According to the Smart SM this has been changed for NA451.

I see no reason to believe the "Gaser" will be less prone to leaks, as the AC line runs are just as long. No one knows how the NA451's AC will perform until a couple of years go buy.

I am picking up a couple of cans of "Duracool" at Canadian Tire this week end...Just in case. A2Jack.

+1 on the Duracool.
This seems to be the fix for the Smarts here. One of the guys had his recharged twice but with the Duracool it seems stable now.
Is Duracool available in the U.S?