A/C Blowing Through Defrost Vents Constantly

[Mr.Smith79]

I'm having a problem with my windshield fogging up and developing condensation on the exterior when using the A/C. I live in Texas and it's close to 100 degrees in the day time and 80 to 85 degrees at night. The problem is that my windshield starts to fog up no matter what I have the A/C set on. I have to repeatedly use the windshield wipers to see, especially at night. Is there anything anyone knows about this problem? I love the car, but can't live with this annoyance.

 

[EdP]

I'm having a problem with my windshield fogging up and developing condensation on the exterior when using the A/C. I live in Texas and it's close to 100 degrees in the day time and 80 to 85 degrees at night. The problem is that my windshield starts to fog up no matter what I have the A/C set on. I have to repeatedly use the windshield wipers to see, especially at night. Is there anything anyone knows about this problem? I love the car, but can't live with this annoyance.

There was a recent thread about this but no conclusive answer. Some get it, other don't. Also depends on weather.

Funny thing is, I said I don't see it but the very next day I had a little bit of condensation. It was just a couple of inches above the defrost vent. That evening, it was 75 degrees and 100% humidity. Not enough that I needed wipers and it formed when I stopped for gas; went away as I drove. .

Is this something new? Could be the dampers for the air are not moving properly and sending a lot of cold air on the windshield. There should be little to none.

Until you find a good fix, try turning the heat on with the defroster for a minute and see if it heats it enough to stop the condensation.

 

[Mr.Smith79]

There was a recent thread about this but no conclusive answer. Some get it, other don't. Also depends on weather.

Funny thing is, I said I don't see it but the very next day I had a little bit of condensation. It was just a couple of inches above the defrost vent. That evening, it was 75 degrees and 100% humidity. Not enough that I needed wipers and it formed when I stopped for gas; went away as I drove. .

Is this something new? Could be the dampers for the air are not moving properly and sending a lot of cold air on the windshield. There should be little to none.

Until you find a good fix, try turning the heat on with the defroster for a minute and see if it heats it enough to stop the condensation.

Thanks for the reply, EdP. This is my 4th Equus and neither of my previous cars produced condensation on the level I'm experiencing now. I'm getting to where I hate to drive it, and am flabbergasted at how a nearly 70k car when new can have issues that cars costing 1/3 of the price never have. I'm going to try your fix to see if it helps.

 

[EdP]

Thanks for the reply, EdP. This is my 4th Equus and neither of my previous cars produced condensation on the level I'm experiencing now. I'm getting to where I hate to drive it, and am flabbergasted at how a nearly 70k car when new can have issues that cars costing 1/3 of the price never have. I'm going to try your fix to see if it helps.

Based on your past experience, good change the defrost damper is not closing all the way. Like I said, a small section is all I had and barely noticable, but to have the entire windsheld fog would bug anyone. Good luck .

 

[DSXMachina]

Based on your past experience, good change the defrost damper is not closing all the way. Like I said, a small section is all I had and barely noticable, but to have the entire windsheld fog would bug anyone. Good luck .

I agree with that possibility. The OP could try putting newspaper (remember them) or some other impervious material over the defrost vents to see if the condensation is gone. Seems likely. That would certainly identify air 'leakage' from the vents as the culprit.
FYI almost all cars, maybe all, have some vent flow no matter what setting you use. There may be no 'fix' possible because it's the way it was designed. Houston in the Summer? Probably the worst conditions for AC in the US.

 

[ancdmd]

I'm down in McAllen, TX and its hot as hell here too but not nearly as humid as Houston. I haven't had any fogging issues. However, I've noticed that when the climate is on auto (I always leave it on auto), the LED light on the A/C button only lights up occasionally, or if the temperature is set well below the interior ambient temperature, but the fan continues to blow at a high setting as if the system is trying to reduce the interior temperature. During my 5-mile commute to and from work the fan will intermittently blow hard, then soft, then hard, then soft again, but the A/C light won't illuminate along with the increase in fan speed. The only way I can get the A/C light to come on is if I drop the temp setting at least 5 degrees or so. After a while I tire of the noisy high fan speed.

Normally cars have a higher fan speed and the a/c is activated as the interior is cooled down to the desired setting. Then the fan slows and the a/c stays on as needed. The climate control system in this car doesn't seem to be able to make up it's mind.

 

[DSXMachina]

I'm down in McAllen, TX and its hot as hell here too but not nearly as humid as Houston. I haven't had any fogging issues. However, I've noticed that when the climate is on auto (I always leave it on auto), the LED light on the A/C button only lights up occasionally, or if the temperature is set well below the interior ambient temperature, but the fan continues to blow at a high setting as if the system is trying to reduce the interior temperature. During my 5-mile commute to and from work the fan will intermittently blow hard, then soft, then hard, then soft again, but the A/C light won't illuminate along with the increase in fan speed. The only way I can get the A/C light to come on is if I drop the temp setting at least 5 degrees or so. After a while I tire of the noisy high fan speed.
Do you smoke in your car? How many miles on it? Is McAllen a dusty area?

 

[EdP]

I'm down in McAllen, TX and its hot as hell here too but not nearly as humid as Houston. I haven't had any fogging issues. However, I've noticed that when the climate is on auto (I always leave it on auto), the LED light on the A/C button only lights up occasionally, or if the temperature is set well below the interior ambient temperature, but the fan continues to blow at a high setting as if the system is trying to reduce the interior temperature. During my 5-mile commute to and from work the fan will intermittently blow hard, then soft, then hard, then soft again, but the A/C light won't illuminate along with the increase in fan speed. The only way I can get the A/C light to come on is if I drop the temp setting at least 5 degrees or so. After a while I tire of the noisy high fan speed.

Normally cars have a higher fan speed and the a/c is activated as the interior is cooled down to the desired setting. Then the fan slows and the a/c stays on as needed. The climate control system in this car doesn't seem to be able to make up it's mind.

That does not sound at all normal. There are a few reasons the AC would cut out, such as the low pressure switch. I'm going to assume the cabin filter has been changed recently enough also. I'd get it checked out.

 

[ancdmd]

I don't smoke. Car is a 2014 with only 18k miles on it. McAllen is a bit dusty since it's usually windy here, 10-25mph wind on almost a daily basis. Cabin filter is changed regularly.

I've resorted to turning off the Auto function, putting it in recirc mode, setting the temp to LOW for driver/pass/rear, and just modulating the fan speed as I see fit.