can't defog PA


PA93
12-27-2005, 12:47 PM
When it's snowy weather or it rains I can't defog my PA (93 with auto climate ctrl) - I turn on the 'defrost' or 'defog' high temp and max speed of the fan but there is still a lot of fog. Why?Is it normal in PA?

wrightz28
12-27-2005, 01:07 PM
Could be:

1-Leaky heater core

2-Stuck blend door to outside air

3-evaporator core problem (clogged drain plug?)

PA93
12-27-2005, 01:24 PM
thanks!!
how can I check it all?Any tips?My PA is in great shape and there is only 92k miles on it.I thought that fog on windows may be normal for PA when it's cold and there's a lot of snow/rain.I'm not sure but it looks like there is more fog on windows on left side of the car.

Mad9C1
01-05-2006, 08:28 AM
thanks!!
how can I check it all?Any tips?My PA is in great shape and there is only 92k miles on it.I thought that fog on windows may be normal for PA when it's cold and there's a lot of snow/rain.I'm not sure but it looks like there is more fog on windows on left side of the car.

The front window defogger/defroster relies on the a/c compressor to kick on. Although we require heat in the winter, the a/c compressor is used to dry the air blowing on the front window, which reduces the moisture that causes the fogginess.

Can you confirm your compressor kicks on when you turn on the front window defogger? I would make sure of this before moving on to other possible issues, as this is the issue with my 1997 PA, and was an issue with a couple other cars I've had in the past. Like many, there may be a leak in the a/c system. The leak causes low refrigerant pressure, and the sensor won't allow the compressor to kick on.

Beyond that, I would like to know if this problem persists when the car warms up, and the front wndow is recieving hot air. Even if the a/c compressor isn't operational, once there is warm air available, you should be able to clear the window's fog pretty easily. If this seems to get worse, instead of better with heat, I'd assume your heater core is leaking, and steaming up your window. I'm assuming for now, this isn't your problem though.

This may sound stupid, but my friend's wife had a similar problem, and he issue was not fog on the inside, but rather, hers was outside, and all she needed to do was turn on the wipers to clear the outside of the window. I assume this isn't your problem either.

Good Luck..

Sam B.

imidazol97
01-05-2006, 09:45 AM
The compressor won't kick on below something like 40 or 45 degrees so check it when the outside temp is warmer.

Don't use the air conditioner compressor (if it works ) on days when the temp is about 40- or so. That puts moisture into the bottom of the box. Your drain may be stopped up that drains the water out that the compressor collects.

If you park your car indoors, leave the windows open to help evaporate the stuff out. IF ourside leave windows down slightly when possible to help dry out the moisture.

Mad9C1
01-05-2006, 09:53 AM
The compressor won't kick on below something like 40 or 45 degrees so check it when the outside temp is warmer.

Don't use the air conditioner compressor (if it works ) on days when the temp is about 40- or so. That puts moisture into the bottom of the box. Your drain may be stopped up that drains the water out that the compressor collects.

If you park your car indoors, leave the windows open to help evaporate the stuff out. IF ourside leave windows down slightly when possible to help dry out the moisture.


This gives me hope mine might not have any issues at all. My 96 bonneville's a/c compressor came on in cooler temps though, which puzzles me now. On the climate control on the bonneville, any time i turned on the heater, or anything, the a/c compressor would go on, and it had a light on the dash to let me know this. I always found myself hitting the auto button for heat, and then i'd hit the a/c button to shut that off. I had the bonneville until a week before christmas when a careless driver smashed it on me. This is why I'm here reading about the PA. Maybe the bonne was malfunctioning, because my brother's 97 bonne's a/c doesn't turn on lately, and we assumed trouble. I now assume it's not going on due to the cooler temps here.
Thanks for the input, I now have something to ponder.

Sam B.

wrightz28
01-05-2006, 10:41 AM
Anytime a deforst setting is selected the a/c compresspr will come on. As shown by this problem, cooler/DRIER air clears a window much more effectively than blowing normal air accross it.

Mad9C1
01-05-2006, 10:48 AM
Anytime a deforst setting is selected the a/c compresspr will come on. As shown by this problem, cooler/DRIER air clears a window much more effectively than blowing normal air accross it.


What you are saying, is what I've believed until the post that said I was mistaken.

Which is correct?

If you are right, then my smashed bonne's system worked fine, and i can confirm the a/c blew ice cold in the summer, and it would also seem my current car, 1997 Park Ave, as well as my brother's 1997 bonne, both have malfunctioning a/c systems.

I do have a noisey clutch on mine, so, I assume I'll be replacing it, with the compressor, and probably the condenser. ...or so I'm told..

Thanks for any info and help..

Sam B

imidazol97
01-05-2006, 01:01 PM
Anytime a deforst setting is selected the a/c compresspr will come on. As shown by this problem, cooler/DRIER air clears a window much more effectively than blowing normal air accross it.

The FSM on page 920 (ESM) says for diagnosis that the ambient temperature should be above 10 deg. C. or 50 deg. F. and check for clutch engagement or cycling.

Do you have a reference that says it should be on all the time?

I just checked my 98 Le Sabre and at 37 deg. F. it's not engaging.
My 03 is engaging at outside temp of 43 deg. F. So the temperature to not activate the compressor is between 37 and 43 deg. F.

wrightz28
01-06-2006, 12:24 PM
The FSM on page 920 (ESM) says for diagnosis that the ambient temperature should be above 10 deg. C. or 50 deg. F. and check for clutch engagement or cycling.

Do you have a reference that says it should be on all the time?

I just checked my 98 Le Sabre and at 37 deg. F. it's not engaging.
My 03 is engaging at outside temp of 43 deg. F. So the temperature to not activate the compressor is between 37 and 43 deg. F.

The what of the what? :wtf:

The +10*c would be refering to as you stated, DIAGNOSIS of the clutch's operation, NORMAL operation.

To protect the system it is obviously not going cycle full time as if it were the middle of July. It is only using the system to dry the air in the sytems evaporator at shorter cycles.

imidazol97
01-06-2006, 01:14 PM
To protect the system it is obviously not going cycle full time as if it were the middle of July. It is only using the system to dry the air in the sytems evaporator at shorter cycles.

If the temperature outside where you are is below 36 degrees, have someone turn on the air conditioner (heater) with the vent setting off so that the compressor would engage in warmer weather. Tell us if the compressor engages or not.

wrightz28
01-06-2006, 01:52 PM
Sure how bout this morning, about 25* set to floor and defrost and she's a engaging, on my 87.

And for that matter a few weeks ago, my Buick, 98 dodge van, 91 toyota, my 85 z28, 96 lumina all when we had 2 and half weeks of below 20*F weather, all had their compressors cycling when DEFROST is selected.

Now, your statement will hold subtantial water if A/C were selected, BUT we are talking about DEFROST.

Whatever your statement was trying to make cunfused the hell out of me:


"have someone turn on the air conditioner (heater) with the vent setting off so that the compressor would engage in warmer weather. Tell us if the compressor engages or not."

of course it won't it's OFF! :dunno:

imidazol97
01-06-2006, 08:34 PM
Sure how bout this morning, about 25* set to floor and defrost and she's a engaging, on my 87.
:

Did you look to see that the compressor hub was turning along with the pulley?

auto trainy
01-07-2006, 08:25 AM
Wright,Ive had three Olds 2 95s and a 98,the 98 has climate control and I had the same issue about the compressor not turning on for defrost in the winter,and I took it in and it was explained to me by personal friend (service mgr.) that the compressor will not be allowed to turn on below 45-55 degreesF.I don't like it because my 95s didn't work like that but he told me it's the design and have to learn to live with it.Heres a side note ,he also informed me that the 98s compressor does not cycle on/off when in operation as the 95 does.I hope that explains it a little easier.

mikelund
01-07-2006, 09:45 PM
I have a 95PA. The Helm manual in section1C-12 under the heading Temperature Controal (C68) states:

"The HVAC programmer controls A/C compressor operation using information from its network of sensors and the heater and A/C control. If the system is operating in any mode but OFF or A/C button deactivated, ambient temperature is above 8'C (48'F) and the programmer does not sense a low refrigerant level condition, it turns on the compressor. System air is then cooled and de-humidified.

System air is heated, as necessary, by passing it through the heater core. An air mix valve, located inside the heater and A/C module assembly, determines how much air passes around the heater core and how much is forced through the core....

The air mix valve is operated by the air mix valve actuator, which is mounted on the heater and A/C module assembly. The actuator contains a reversible DC motor that is powered by the HVAC programmer...."

imidazol97
01-08-2006, 02:45 PM
The posts seem to indicate 48 degrees and below for the compressor to run. Some compressors are continuous or variable V5 or V555, I forget the exact designation, and run all the time.

Second factor is the lowering of vapor pressure of the refrigerant at lower temperatures. It drops the pressure in the system below the low pressure limit switch. This prevents the system from turning on to protect itself from low refrigerant levels in case of a leak.

wrightz28
01-09-2006, 12:43 PM
ah hah, maybe this is where our disagreement lies, I wasn't thinking about the digital climate controlled system. All mine are traditional manual operation.

imidazol97
01-09-2006, 03:22 PM
I had wondered if there was a difference there.

I had a 93 LeSabre and it was the manual system. I believe the temperature sensor was in the A-pillar, IIRC. So sometimes that was warmer until you started driving and it cooled down when out of the garage.

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