Front defrost, engine power fluctuations

[ISP_guy]

Hi folks -

2015 DE

I notice when I put my front defrost on in the mornings the car has a pulsing/surging effect driving down the road, as if it's working harder to power the heater or something. If I kick it off of defrost and into the main upper/floor vents the problem disappears. It seems to happen no matter which temperature I set it at, and only on front defrost. (I don't use AC, not sure if that has a similar issue).

I don't have my headlights on in the mornings and no electronics enabled - only the radio, and not really that loud. Car is all factory - no mods besides front LED parking lights.

I don't notice any lights dimming or other electrical power issues, just sort of an engine surge/pulse. Car starts up every morning and runs fine otherwise. Rear defrost doesn't seem to trigger any problems either.

I'm stumped as to why it surges only on the defrost setting, and not on ALL vent/heater settings. Something to be concerned about, or functioning "as expected"?

[inuvik]

Hi folks -

2015 DE

I notice when I put my front defrost on in the mornings the car has a pulsing/surging effect driving down the road, as if it's working harder to power the heater or something. If I kick it off of defrost and into the main upper/floor vents the problem disappears. It seems to happen no matter which temperature I set it at, and only on front defrost. (I don't use AC, not sure if that has a similar issue).

I don't have my headlights on in the mornings and no electronics enabled - only the radio, and not really that loud. Car is all factory - no mods besides front LED parking lights.

I don't notice any lights dimming or other electrical power issues, just sort of an engine surge/pulse. Car starts up every morning and runs fine otherwise. Rear defrost doesn't seem to trigger any problems either.

I'm stumped as to why it surges only on the defrost setting, and not on ALL vent/heater settings. Something to be concerned about, or functioning "as expected"?

It's your AC compressor kicking on and off to dry the air. I avoid using the button for this reason and just change the mode for air flow to the split floor/windshield setting and turn up the fan. If I do have to use it I'll keep the mode mix the same push the button and as soon as the window clears shut th defrost button off

[ISP_guy]

I will give that a try tomorrow morning. Thank you for the info! I also noticed a hazy film developing inside my windshield which is super noticeable when the sun hits just right or the windshield fogs up. I don't smoke or carry any smokers in the car. I'm curious where this might have come from... the car is only 6 months old from the dealership. Maybe just some junk on the heater core or whatever that is blowing up inside the car when I kick the defrost on? Or condensation/goo from the AC compressor?

[MightyMirageMpg]

Yes the auto air controls are simply not what ide consider an option. More of a dilemma.

Someone once said you can turn off the ability for it too turn the a/c on automatically by pressing the snowflake button from 10 seconds. I tried this and my car signaled a responsee, but it still does it.

Maybe someone could post a quick video or a better explination of how to alter this?? Kind of a frequent question

[Eggman]

It's one of the first changes I made to my Mirage. Give it a try yourself.

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Personalizing the air conditioning switch (Changing the function setting)

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You can change the following functions to match your preference.
• Enable automatic air conditioning control:
When the AUTO switch is pressed, or when the temperature control switch has been set to the minimum temperature, the air conditioning switch is automatically controlled.
• Disable automatic air conditioning control:
The air conditioning switch is not automatically controlled, unless the air conditioning switch is used.
• Changing the settings:
Press the air conditioning switch for about 10 seconds or longer. When the setting has changed, the system will beep and the “❄” indicator will flash.
•When the setting has changed from enabled to disabled, the system will beep three times and the indicator will flash three times.
•When the setting has changed from disabled to enabled, the system will beep two times and the indicator will flash three times.

Note

• The factory setting is “Enable automatic air conditioning control”. • When the defogger switch is pressed, the air conditioning will run automatically, even if the system is set to “Disable automatic air conditioning control”, in order to prevent windows from fogging up.

[MightyMirageMpg]

It was indeed that basic, huh? I must have goofed up the first time i did it (or did it twice lol). Thanks

[Eggman]

Keep in mind the note at the bottom that says if defogging is selected - that is, to clear the windshield - the AC compressor will turn on to help the process. This describes manual selection of defogging, not automatic operation.

It's been some months since I have had to do it, but I remember during colder weather I left my system in Auto and let the car manage climate control. Upon a cold start, the fan ran slow until warmup. Then the fan speed would increase and direct air over the windshield for a bit, until the cabin reached the temperature called for then the fan would slow. I thought it worked great, and I don't remember the AC compressor cycling as ISP_guy describes.

In these warmer days, I have forgotten about this operation. I guess I'll have to use it this morning to see how it works.

[ISP_guy]

I used the windshield/floor setting this morning as MightyMirageMpg suggested and it seemed to work well enough. Thank you Eggman, I will give that a try as well!