Front Windshield Defroster - Poor Performance

oregon2 · Nov 14, 2006

We came home from the football game the other nite- raining, 45 degrees, and 3 people in the car (a little wet- but not bad). The front windshield would not clear and by the time we got home (15 minute drive) it was only 1/2 defrosted -- plus the rear window was also only 1/2 defrosted. I have owned a ton of cars in 40 years of driving and have never encountered this problem. My wife (she is primary driver) said she has noticed this on several occasions.

'05 SE

Blak_on_Blak · Nov 14, 2006

It is possible something is blocking the airflow across the cabin filter element. Perhaps leaves or dirt have clogged it causing this to occur. I know I had a similar situation, where the windows kept fogging and a new filter solved that problem. No fog at all since...

Tyler_Canada · Nov 14, 2006

Did you turn the A/C off? It's needed even when not cooling the temperature in order to dry the air out and defrost the windows.

njjoe · Nov 14, 2006

oregon2-

Was it frost on the outside of the glass or moisture on the inside of the glass?

-njjoe

Eric L. · Nov 14, 2006

I find the defogger on my MO works great, provided you turn up the heat a bit (over 65) and make sure the AC is on.

oregon2 · Nov 15, 2006

njjoe said:
oregon2-

Was it frost on the outside of the glass or moisture on the inside of the glass?

-njjoe

It was moisture on inside of glass- not cold enough (45 degrees) for frost.

oregon2 · Nov 15, 2006

Eric L. said:
I find the defogger on my MO works great, provided you turn up the heat a bit (over 65) and make sure the AC is on.

We turned the heat up as high as 80 ----with no improvement.

Checked tonite- turn on Defrost and yes, A/C comes on. Can feel air out all 4 vents on top of dash.

njjoe · Nov 15, 2006

oregon2 said:
It was moisture on inside of glass- not cold enough (45 degrees) for frost.

Difficulty in removing moisture from the inside of the glass can be attributed to one of two things: 1) The HVAC is incorrectly set to RECIRCULATE, when it should be set to FRESH air; and/or 2) the A/C was not enabled.

Next time you encounter those conditions make sure the HVAC is set for FRESH air and the A/C light is illuminated.

That should do the trick.

-njjoe

oregon2 · Nov 15, 2006

njjoe said:
Difficulty in removing moisture from the inside of the glass can be attributed to one of two things: 1) The HVAC is incorrectly set to RECIRCULATE, when it should be set to FRESH air; and/or 2) the A/C was not enabled.

Next time you encounter those conditions make sure the HVAC is set for FRESH air and the A/C light is illuminated.

That should do the trick.

-njjoe

Checked tonite- when I turned on front defrost-- A/C and FRESH air automatically come on (buttons light up).

Gonzo · Nov 15, 2006

With the AC on have fresh air or recirc air doesn't really matter. The big thing is that the AC was on.

I would make sure your AC is working... sounds like it is not.

Eric L. · Nov 15, 2006

Gonzo said:
With the AC on have fresh air or recirc air doesn't really matter. The big thing is that the AC was on.

I would make sure your AC is working... sounds like it is not.

I agree. My window starts to clear immediately with the defog on. It does sound like the AC isn't working right above.

oregon2 · Nov 16, 2006

Gonzo said:
With the AC on have fresh air or recirc air doesn't really matter. The big thing is that the AC was on.

I would make sure your AC is working... sounds like it is not.

Checked operation - turn on front defrost - A/C compressor and electric fan come on for 5 seconds - then shuts off for 15 seconds- and continues to repeat this cycle. Is that NORMAL ??

Eric L. · Nov 16, 2006

oregon2 said:
Checked operation - turn on front defrost - A/C compressor and electric fan come on for 5 seconds - then shuts off for 15 seconds- and continues to repeat this cycle. Is that NORMAL ??

That doesn't sound normal - it should be on continuously when the defog is on.

oregon2 · Nov 16, 2006

Eric L. said:
That doesn't sound normal - it should be on continuously when the defog is on.

Would you mind if you get a chance to check yours and see if it does this same 5 sec on -15 sec off routine ?? Then we would know for sure if this is the problem.

thanks

Eric L. · Nov 16, 2006

oregon2 said:
Would you mind if you get a chance to check yours and see if it does this same 5 sec on -15 sec off routine ?? Then we would know for sure if this is the problem.

thanks

Ok I'll listen tomorrow. Its been raining lately so I've had defog on continuously.

njjoe · Nov 16, 2006

oregon2 said:
Checked operation - turn on front defrost - A/C compressor and electric fan come on for 5 seconds - then shuts off for 15 seconds- and continues to repeat this cycle. Is that NORMAL ??

O2-

Yes, that is normal. The A/C compressor will cycle to maintain a maximum temperature in the evaporator core. If it was to run continuously you would risk freezing-up the evaporator coils.

-njjoe

njjoe · Nov 16, 2006

Eric L. said:
That doesn't sound normal - it should be on continuously when the defog is on.

E-

No, it should not be on continuously.

Just because the compressor is not running does not mean that the A/C system is not cooling and dehumidifying the air. When the compressor cycles off there is still a cooling effect in the evaporator core because 1) the expansion valve continues to meter high-pressure liquid freon in to the lower-pressure core, and 2) the relatively cold evaporator acts as a heat sink and continues to absorb heat from the air.

-njjoe

Eric L. · Nov 16, 2006

I'll have to listen to mine more carefully, but honestly I've never heard the compressor cycling, only the second electric fan. If they both happen at the same time, then maybe the fan switch is louder than the AC clutch.

oregon2 · Nov 16, 2006

Eric L. said:
I'll have to listen to mine more carefully, but honestly I've never heard the compressor cycling, only the second electric fan. If they both happen at the same time, then maybe the fan switch is louder than the AC clutch.

Just open the hood and it is real easy to observe (and hear) the compressor cluch engaging and disengaging .........and yes, the fan comes on at the same time.

Gonzo · Nov 16, 2006

If you have a cooking thermometer, stick it in the vents... see what you get for a reading. Depending on the outside airtemp it should be significantly cooler than outside.

If it is cooler (this time of year at least 20°F) then you have just **GOT** to stop making out in the car while driving.

Eric L. · Nov 16, 2006

Had a look and a listen this morning - yeah you are right, the compressor clicks on the same time the secondary electric fan does. However, I did not have a 5 second / 15 second cycle, it was more random. Over two minutes, the compressor sometimes turned on for as long as 20 seconds, sometimes as short as 3 seconds, there didn't seem to be a pattern - but as joe says, its whatever it takes to keep the system pressurized.

Gonzo · Nov 17, 2006

As the car ages the compressor will run more due to leaks in the system developing. Then it will evendutally come to a point when the compressor is on all the time and you get nothing out of.

That will be a sad day for the MO.

njjoe · Nov 17, 2006

Gonzo said:
As the car ages the compressor will run more due to leaks in the system developing. Then it will evendutally come to a point when the compressor is on all the time and you get nothing out of.

That will be a sad day for the MO.

G-

With any luck, that will coincide with the day you are trading in the MO for another.

-njjoe

oregon2 · Nov 17, 2006

OK guys- we have been around the block once now and I am still searching for an answer. Here is what I know:

1) compressor and outside air functional when DEFROST on
2) might be plugged cabin filter - but at 10k miles- I rather doubt it
3) "If it is cooler (this time of year at least 20°F) then you have just **GOT** to stop making out in the car while driving. ............"
ELIMINATE THIS AS THE PROBLEM- THAT SHIP SAILED A LONG TIME AGO -BESIDES I AM NOT SURE WARRANTY WOULD COVER THAT

So where do we go from here --- except to the dealer......and you know what they are going to say.............

Eric L. · Nov 17, 2006

oregon2 said:
OK guys- we have been around the block once now and I am still searching for an answer. Here is what I know:

1) compressor and outside air functional when DEFROST on
2) might be plugged cabin filter - but at 10k miles- I rather doubt it
3) "If it is cooler (this time of year at least 20°F) then you have just **GOT** to stop making out in the car while driving. ............"
ELIMINATE THIS AS THE PROBLEM- THAT SHIPPED SAILED A LONG TIME AGO -BESIDES I AM NOT SURE WARRANTY WOULD COVER THAT

So where do we go from here --- except to the dealer......and you know what they are going to say.............

Does the windshield clear faster if you manually turn the fan to max?

oregon2 · Nov 17, 2006

Eric L. said:
Does the windshield clear faster if you manually turn the fan to max?

Turn the TEMP UP....... Turn the FAN to hurricane speed .......the results are the same: a half defrosted window.:1:

Front Windshield Defroster - Poor Performance

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