Taking a survey. How cold is your AC?

There's been a lot of talk about AC lately (duh, that time of year)

I'm wanting some hard numbers
So if you have one of these


help me out by posting here like this
outside temp, temp at center vents, if you are using 134a or 12.

Thanks in advance.

I'll start.

60, 102, R12
50, 90, R134a

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_{Buddy Craigg - there are two "G"s in my last name
Ling = 84SE-Modified
Julia C = 85GT stock (kinda)
Ivy = 67 Pontiac Catalina
KCFOG}

I checked mine last week Thursday and it was 92* outside with 80%+ humidity, and I had 38* air from the vents with it on Max and the fan setting on the second notch.

My car has a SC3800II motor so the compressor is a newer 134a type compressor. I converted the car to 134a a few weeks ago.

[This message has been edited by topcat (edited 07-17-2006).]

Anywhere in the 30s is cold, anywhere in the 40s is acceptable. I once did an A/C service on a early 90s Toyota and the vent temps were in the low 20s.

I'm no A/C expert but you need a few more pieces of data.

If you want to do this scientifically, in addition to outside air temp you need the humidity, (or dew point). You need to put the car in the shade to elliminate that variable, and you need to specify fan speed, (air is colder the slower the airflow because it has more time in the evaporator), type of of compressor, (DA9, V5, Caddy, etc), and probably a few other things I forgot.

To answer your question I do have a vent thermometer, and with 95F outside, I can get 45F on the lowest fan speed using R134a


And vent temperatures in the 20s are impossible. The evaporator would be a solid block of ice.

I am not sure about what is possible in regards to the temp at the vents, but a few years back while in the deserts of Oman, my car put out super ice cold air. The AC over there was so much more efficient than what we have here. I am not sure if they had larger capacity systems, used a different refrigerant, or larger fans for the condenser... I just know it was colder at the vents. I never checked the temps at the vent, but with 110* temps outside, the AC would blast me out of the car if I kept it on max with the fan on high. I often had to adjust the temp control to keep it cold, but not freezing inside the car.

Oh, I had a 2000 Malibu at the time, then switched to a Honda Accord.

quote Originally posted by jscott1: I'm no A/C expert but you need a few more pieces of data. If you want to do this scientifically, in addition to outside air temp you need the humidity, (or dew point). You need to put the car in the shade to elliminate that variable, and you need to specify fan speed, (air is colder the slower the airflow because it has more time in the evaporator), type of of compressor, (DA9, V5, Caddy, etc), and probably a few other things I forgot. To answer your question I do have a vent thermometer, and with 95F outside, I can get 45F on the lowest fan speed using R134a And vent temperatures in the 20s are impossible. The evaporator would be a solid block of ice.

asking people to have all that information for their responce is more than what i expect.

remember.
keep it simple, make it fun.

[This message has been edited by buddycraigg (edited 07-17-2006).]

Its 115 outside and my A/C blows a breezy 120 degrees. One day I will have A/C in both my cars.

quote Originally posted by jscott1: I'm no A/C expert but you need a few more pieces of data. If you want to do this scientifically, in addition to outside air temp you need the humidity, (or dew point). You need to put the car in the shade to eliminate that variable, and you need to specify fan speed, (air is colder the slower the airflow because it has more time in the evaporator), type of of compressor, (DA9, V5, Caddy, etc), and probably a few other things I forgot. To answer your question I do have a vent thermometer, and with 95F outside, I can get 45F on the lowest fan speed using R134a And vent temperatures in the 20s are impossible. The evaporator would be a solid block of ice.

That's what I would have thunk but I measured it with a thermometer like the one showed and a non contact type, drove to a friend's house and showed him. If you want I will get an affidavit signed by him. and I don't think it's impossible.

its all about the delta tempature (change) about 20* is considered normal in decent heat. of course this will be higher in low tempatures though I wouldnt expect less in high tempatures

Well the yard is 79 so I guess thats what it is, its on the floor of my garage.

you people are incorrigible

ok, my lat fiero, 86 se, r12, 90+ outside, highway rush hour driving, avg 20-50 mph, max setting, fan medium, typical was 34 at the center vent. at 85 ambient, it blew fog if I opened the windows, guage was sitting around 32.
present 88gt, h6 compressor , r12, ambient 96 degrees, center vent 96 degrees. ( the compressor worked for one week fter fixing the switch o ring, then blew the front seal. for the short time it worked, only checked it sitting in driveway, 38-40 degrees, max, fan one notch off low, ambeint was around 80.
I have to find a new compressor !!!!!!!

it is possible to go below 32 degrees on a low humidity day with moderate ambient air, if the car is not moving, it will remove all the moisture in the car fairly quickly, so the evap will remain dry enough to not turn into a block of ice.

quote Originally posted by Kekipi: That's what I would have thunk but I measured it with a thermometer like the one showed and a non contact type, drove to a friend's house and showed him. If you want I will get an affidavit signed by him. and I don't think it's impossible.

The evaporator in a car is not designed to cool air below freezing..32F If it did the water condensing on the coils would turn to ice and soon there would be a solid blockage of ice and no airflow. I would have to see that with my own eyes to believe it.

By the way these systems operate far more efficiently in dry heat. So it's not unusual to have better performance in the 110F of the desert compared to 95F and 100% RH

Actually AC systems can freeze up in some cases. If your coolant is weak they have also been known to freeze the heater core. (The heater core is after the evaporator in the air stream.)

If I remember right... The desired minimum spec is 40-50*F drop across the evaporator. This varries some about humidity etc but that general spec has been used for years to evaluate system operation. It seems to hold up pretty well still.

Mine runs to about that spec. R134 loaded.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurasic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

I recently converted mine to 134A and I was getting 41* at the center vent at idle with the fan on high and all other vents closed and the AC set at MAX.

Ambient temp was mid to high 70's.

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Where will the road take you today?

Some helpful links I've done
How to remove inner door panels, with pics.
How to remove outer door panels, with pics.
How to make rear coil-overs using factory struts, with pics.
How to remove rear bearing hubs, with pics.
How to modify the stock Fiero radio for MP3 players, with pics.

i removed my catty remarks

have a nice night.

[This message has been edited by buddycraigg (edited 07-18-2006).]

I checked this a few weeks ago in my 88 GT. I believe that the AC on this car has never been serviced.

So at night when it cools down to 100 F in Phoenix with humidity no more than 20 percent, my center vent registered 47 F while running on an expressway. I didn't think this was too bad.

[This message has been edited by atjxl (edited 07-18-2006).]

Well lets see, with my fan on high with it on recirculate i get about 38 out the vents. This is when the ambient is 110, about 35-40 percent humidity. It has the HR6 compressor with R12.

On a 95 degree day with the AC on Max and the fan on High, I get 36 degrees at the driver's side AC outlet with the engine idling. That's using R12 and an unmodified factory AC system; do I win a prize? (grin).

The fellow up above who was claiming temperatures in the 20's - either the thermometer is wrong or that system is broken. If the evaporator goes below freezing, it'll frost up and shut down the air flow. All AC systems are equipped to prevent the evaporator from going down to freezing...

[This message has been edited by Whuffo (edited 07-18-2006).]

87 GT = 40 , 87 Coupe = 40 , 88 Formula = 45

Used the same meter, outside temp 90

All three systems are not converted. Set to max a/c, fan speed 2

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More photos, http://www.cardomain.com/ride/278279

quote Originally posted by Whuffo: On a 95 degree day with the AC on Max and the fan on High, I get 36 degrees at the driver's side AC outlet with the engine idling. That's using R12 and an unmodified factory AC system; do I win a prize? (grin). The fellow up above who was claiming temperatures in the 20's - either the thermometer is wrong or that system is broken. If the evaporator goes below freezing, it'll frost up and shut down the air flow. All AC systems are equipped to prevent the evaporator from going down to freezing...

Usually the capillary tube senses too cold and opens the valve wider but Two thermometers and a friend that does A/C also. Seeing is Believing

I had R12 in the Ferraro and it would litterally freeze you out no matter how hot it was outside. My Corvette also had R12 and it was ice cold. Recently I had to repair the vette and had the dealer upgrade it to 134. My seat of the pants feel is its probably half as efficient now. Barely keeps you cool at full blast. Also my Lumina van and Dodge Magnum (both 134) on these 90+ days barely makes it comfortable on full speed and all the way cold. With the Ferraro and vette, on 90 and up days, after a few minutes on high you could be fine with it on low for the rest of the trip.

88GT==40`ish 3800SC ==134a
86Gt==40---------- 2.8====R-12
86Gt==40`ish------2.8====R-12--SBC Canidate
86GT==40`ish------2.8====R-12--LS-1 Canidate
86SE== 37`ish-----2.8====R-12
87Gt==0`ish----3.2 stroked--not done--R-12
temp outside 95 with heat index

38, 93, 134a

converted to r409a
outside air about 80 f in the sun
car idling
fan on high speed
air set at max
constant 34 out of center vent

too da?? cold even on lowest setting, must turn temperature to 1/3 on heat/cold slider

42-45 at the center vent. Fan on medium. Switch on "norm". ~90 degress outside. R134. DA6 compressor.
Not as efficient at idle.

I haven't measured the A/C on the 4.9, but it will freeze you out of the car. Caddy compressor. R134.

since you guys are throwing in different freons, i figure i better post this cheat card

quote Originally posted by Kekipi: Usually the capillary tube senses too cold and opens the valve wider but Two thermometers and a friend that does A/C also. Seeing is Believing

If you know a way to make a Fiero blow air in the 20 degree F range, I want to mod my system that way... (I'm serious) This heat in Texas has been unbelieveable.

I used to have a '71 Ford Torino back in High School. If I drove around with the fan on low speed and the Temp slider all the way on Cold, that thing would freeze up solid even on 95+ degree days with humidity above 85%. That was the best darn a/c I have ever had in a car!

Look at the charts that buddycraig posted. The temperature of the refrigerant is directly proportional to the pressure. So if you want the lowest vent temps, then you want the fan on the lowest speed and the pressure on the low side has to be as low as you can get it. But to get a low pressure on the low side, you cannot have super high pressure on the high side... there is only so much of a differential that you can maintain through the compressor and the expansion valve or orifice tube. So to get lower pressure on the low side, you have to have lower pressure on the high side. And the only way to do that is to lower the temperature on the high side. Did I already mention temperature and pressure are directly proportional???

So how can you get lower pressure on the high side? Simple physics. More airflow thru the condensor. Or a more efficient condensor, like a Parallel Flow versus the old tube and fin that our Fieros have.

quote Originally posted by Formula350: Or a more efficient condensor, like a Parallel Flow versus the old tube and fin that our Fieros have.

Are there any drop in replacement condensers that fit in a Fiero?

BTW - I got the A/C on my Red GT to work simply by filling it with R134a...I have to top it off about every 18 months. It's pretty cold, but I wouldn't mind it being colder.

quote Originally posted by jscott1: Are there any drop in replacement condensers that fit in a Fiero?

I do not know of any drop-ins, but there are universal ones that could be adapted fairly easily. Let me look into it some more and see if I can come up with something.

BTW Jonathan, I noticed your rating at 299 and just couldn't stand it. So I gave you a + to make it an even 300. You've done a marvelous job with that GT!!

[This message has been edited by Formula350 (edited 07-18-2006).]

quote Originally posted by Formula350: You've done a marvelous job with that GT!!

Thanks, it helps when you have a nice clean car to start with. The previous owner told me all the A/C needed was to be filled and he was right

mmmmmmmm .

[This message has been edited by rogergarrison (edited 07-19-2006).]