No need to disect a system from a newer truck. The Burb with rear air has a seperate air system in teh rear.
Same basic setup as the newer ones it think.
CK5
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Blower motor mod
- Thread starter GalDemSuga
- Start date
No need to disect a system from a newer truck. The Burb with rear air has a seperate air system in teh rear.
Same basic setup as the newer ones it think.
haha i just assumed this was new technology. had no idea they had it back then. learn something new everyday
So running AC at less than the max fan speed makes the interior colder? The problem is volume vs. temperature. Vehicle interior heats up easily, while the AC temp is more or less "fixed". The amount of heat transferred (or taken) from the coil to the air in a certain amount of time isn't going to decrease because speed of the air increases.
Why? Why would I waste the time posting them and why would you need equations to be proven wrong? The concept is not hard to understand...
Use the above mentioned candle example. It's pretty basic physics. Now if you're moving air slowly enough that it gets cooled to the point where it won't get cooled any further, then yes, by all means, move more air. If the truck's A/C factory system can cool the air faster than the factory fan can move it, then yes, I'd agree that more air past the coils would equal better cooling. But there is always a point of diminished return.
If you're smart enough to understand any "equations" that I could possibly post, then you're smart enough to understand the basic principles of heat transfer.
It makes the air coming out of the vent cooler... It's hard to say at which point maximum cooling throughout the entire cab will occur.
Way too many variables to say that increasing or decreasing flow will actually make the setup work better.
However, I'd venture to say that for the given era, GM knew what they were doing with volume and velocity.
However, I'd venture to say that for the given era, GM knew what they were doing with volume and velocity.
ngoluba
Registered Member
Perhaps a way to approach this is thinking in terms of BTU transfer.
If there is no airflow over the cold coils, the passenger compartment will not be cooled at all.
If a small volume of airflow is pushed slowly over the coils, the output air will be very cold, but there is not enough volume to fully extract the BTU capacity of the system or provide distribution throughout the entire passenger area.
If there is a large volume of air pushed across the cooling coils, the temperature drop of the output air will not be as large because of the limited contact time with the coils, but you will come closer to utilizing the full BTU capacity of the cooling system. You will also have better circulation/distribution in the occupant area.
Given this common sense line of reasoning, I would think more air is better until you reach the BTU limit of your cooling system, after which you only get better circulation/distribution in the passenger compartment.
Given all the outlets are in and under the dash, there are pros and cons to better circulation. Front seat passengers get a greater localized cooling effect with a smaller volume of colder air. Back seat passengers are cooled better by more volume at the expense of a warmer temperature for front seat passengers.
There may be some peculiarities in thermodynamics that are not being taken taking into consideration. My guess is that heat transfer is most efficient the larger the temperture differential. If so, then I would think this would be another argument in favor of more airflow.
If there are some engineers out there that can reveal additional thermodynamic priniciples, I would welcome being schooled. Always looking to learn more.
And I second the "crack the rear window" technique.
If there is no airflow over the cold coils, the passenger compartment will not be cooled at all.
If a small volume of airflow is pushed slowly over the coils, the output air will be very cold, but there is not enough volume to fully extract the BTU capacity of the system or provide distribution throughout the entire passenger area.
If there is a large volume of air pushed across the cooling coils, the temperature drop of the output air will not be as large because of the limited contact time with the coils, but you will come closer to utilizing the full BTU capacity of the cooling system. You will also have better circulation/distribution in the occupant area.
Given this common sense line of reasoning, I would think more air is better until you reach the BTU limit of your cooling system, after which you only get better circulation/distribution in the passenger compartment.
Given all the outlets are in and under the dash, there are pros and cons to better circulation. Front seat passengers get a greater localized cooling effect with a smaller volume of colder air. Back seat passengers are cooled better by more volume at the expense of a warmer temperature for front seat passengers.
There may be some peculiarities in thermodynamics that are not being taken taking into consideration. My guess is that heat transfer is most efficient the larger the temperture differential. If so, then I would think this would be another argument in favor of more airflow.
If there are some engineers out there that can reveal additional thermodynamic priniciples, I would welcome being schooled. Always looking to learn more.
And I second the "crack the rear window" technique.
75GmcJimmy4x4
1/2 ton status
what about using a larger coil from say a 18 wheeler ?
That's essentially what I was getting at to begin with... simply pumping more air in more than likely won't help much, if at all.
I snipped a bunch out, but yes, good explanation... The reason cracking a window works is simple physics.
1st off, don't run the air on "max". "Max" recirculates air. Normal does not. If you are drawing in fresh, cold air, and crack a window, the hot air will be pushed out by the cold air coming in. So instead of trying to cool off the hot air, you're replacing it.
I've found that even my big Chevy Express work van gets pretty comfortable fairly quickly. Now it's second nature. I get in, kick on the A/C and crack the window about 1/8"-1/4".
You'd probably need to upgrade the rest of the components as well. The compressor would need to be able to move a larger volume of refrigerant, for example...
Yes, you have to think in terms of heat transfer. Who cares what temperature a certain portion of air is at? The important question is how much heat is being carried out of the interior of the vehicle. There is no reasonable blower (i.e. that you can live with...) that will be "too much" air for the evap.
The more air you move through the evap, the warmer it gets. The warmer the evap, the hotter the condensor. The hotter the condensor, the more heat it eliminates. The limiting factor in the system is how much heat you can get out of the condensor. Until you have it at max pressure, more blower gives you more heat transfer.
The more air you move through the evap, the warmer it gets. The warmer the evap, the hotter the condensor. The hotter the condensor, the more heat it eliminates. The limiting factor in the system is how much heat you can get out of the condensor. Until you have it at max pressure, more blower gives you more heat transfer.
People, People, People. You are all overthinking the problem.
The problem is not how do we re-engineer the cooling system so we can cure meat as we drive.
The problem is the man's dog is hot.
The easiest way is the way I used with my dog. Let the dog ride in the front seat.
But, if there is some reason that is not practical, then go down to your local auto parts place, and pick up one of those 12v fans you see in big trucks and whatever.
Mount it where it blows air from the front onto the dog and that should do it.
You might even be able to just have it blow air from the back to the front to circulate the air and let all of it get cooled evenly.
As for getting your fan to put out more air, hard to do. The amount of air moved changes roughly to the cube of the power.
I know there is a better way to say that, but I'm tired tonight.
Basically, to double the amount of air, it takes 8 times the power. (2X2X2) Roughly.
J.
The problem is not how do we re-engineer the cooling system so we can cure meat as we drive.
The problem is the man's dog is hot.
The easiest way is the way I used with my dog. Let the dog ride in the front seat.
But, if there is some reason that is not practical, then go down to your local auto parts place, and pick up one of those 12v fans you see in big trucks and whatever.
Mount it where it blows air from the front onto the dog and that should do it.
You might even be able to just have it blow air from the back to the front to circulate the air and let all of it get cooled evenly.
As for getting your fan to put out more air, hard to do. The amount of air moved changes roughly to the cube of the power.
I know there is a better way to say that, but I'm tired tonight.
Basically, to double the amount of air, it takes 8 times the power. (2X2X2) Roughly.
J.
