chucko
Veteran Member
think it would be easy to take a junk yard ac system out of a car mount to a carryall and convert it to run off the PTO? Think 540 would turn the compressor fast enough to do any good?
Any one know about car type ACs?
- Thread starter chucko
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rdbrumfield
Veteran Member
what is your application, aircompressor or conditioning
at 540 you won't get much cfm. they are made to run the speed of the car engine, from 500-6000
I used a 74 celica two piston for an aircompressor on one of my trucks. It has it's own crankcase. put a master switch in the cab and an electrical shut off on the tank to kick out the compressor when up to pressure. Be sure to put a mechanical popoff in case you have an elecrical malfunction. will make the tank a bomb.
you might put a belt to it to speed it up, I would think you would want to turn it at least 2000 rpm
at 540 you won't get much cfm. they are made to run the speed of the car engine, from 500-6000
I used a 74 celica two piston for an aircompressor on one of my trucks. It has it's own crankcase. put a master switch in the cab and an electrical shut off on the tank to kick out the compressor when up to pressure. Be sure to put a mechanical popoff in case you have an elecrical malfunction. will make the tank a bomb.
you might put a belt to it to speed it up, I would think you would want to turn it at least 2000 rpm
brandoro
Platinum Member
If you are planning to use it to cool the cab of the tractor I think 540 RPM would be adequate. The AC in the car is cooling a bigger space and only runs the compressor a few seconds at a time even at low engine RPM. You will also need a fan for the condensor, I don't think you will be able to get enough speed out of your tractor for airflow
ampsucker
Platinum Member
conditioning what?
auto a/c is sized to cool a car or truck size cabin from 140 degrees F on a hot summer day down to "comfort" in a just a few minutes. you're looking at around 15,000 btu or more at a 5-15 hp draw for that ability. this is much more than a typical window sized home unit where the requirements are not as demanding (insulated walls and ceiling, less radient heat, longer to do the job).
do you really need that much conditioning power that you are willing to run your tractor wide open to get 540 rpm?
if you just want to cool a small cab on the tractor itself, i would look into finding the smallest compressor you can find and either running it electrically from the tractor alternator or rigging up a belt direct to the engine to drive it more efficiently and faster at closer to engine rpm. for that type of application, something in the range of several thousand btus whould easily be sufficient and would consume only a horse power or two.
in fact i have a cooler in my truck that operates on a danfoss type compressor on DC 12 volt and will keep the cooler frozen for less than 35 watts continuous. you could rig up something like that more easily, i would think.
amp
auto a/c is sized to cool a car or truck size cabin from 140 degrees F on a hot summer day down to "comfort" in a just a few minutes. you're looking at around 15,000 btu or more at a 5-15 hp draw for that ability. this is much more than a typical window sized home unit where the requirements are not as demanding (insulated walls and ceiling, less radient heat, longer to do the job).
do you really need that much conditioning power that you are willing to run your tractor wide open to get 540 rpm?
if you just want to cool a small cab on the tractor itself, i would look into finding the smallest compressor you can find and either running it electrically from the tractor alternator or rigging up a belt direct to the engine to drive it more efficiently and faster at closer to engine rpm. for that type of application, something in the range of several thousand btus whould easily be sufficient and would consume only a horse power or two.
in fact i have a cooler in my truck that operates on a danfoss type compressor on DC 12 volt and will keep the cooler frozen for less than 35 watts continuous. you could rig up something like that more easily, i would think.
amp
madpogue
Silver Member
Actually, a car's A/C compressor turns significantly faster than the engine, since its pulley is usually smaller than the crankshaft pulley. 540 RPM would be equivalent to a crankshaft speed of about 300-350. Of course, you could employ the same trick; use pair of differently-sized pulleys to raise the RPM.
And most modern A/C compressors don't cycle on and off, but operate at "variable displacement", meaning a valve opens and closes variable to move a fraction of what the compressor is actually capable of pumping. But it's not a small fraction, so even if you could get the compressor to turn at, say, 1000 RPM, I don't think you're gonna get a lot of output.
There are multiple other challenges. Where do you put the dryer? Or whatever they call the part that sits in front of the radiator of the car? It's usually pretty big, about the same area as the radiator. Air has to pass through it pretty quickly; that's why the car's cooling fan is programmed to turn on whenever the A/C is running.
The BIG challenge, though, is that the A/C is usually integrated in to the car's powertrain control module (the engine computer). "Weaning" it from the PCM, to run on some mechanical control, would be a project.
One thing I've seen -- I am NOT making this up -- some folks with old beater cars have come up with "ghetto" A/C units using -- don't laugh -- Igloo-type coolers full of ice or those gel ice packs, and fans. You cut an opening in the lid of the cooler and mount one or two of those 12VDC fans like you see in desktop computers (they make bigger ones, too), and wire it to the car's electrical system. I know this sounds totally "you might be a redneck if....", but it's been done, and apparently it's pretty effective.
And most modern A/C compressors don't cycle on and off, but operate at "variable displacement", meaning a valve opens and closes variable to move a fraction of what the compressor is actually capable of pumping. But it's not a small fraction, so even if you could get the compressor to turn at, say, 1000 RPM, I don't think you're gonna get a lot of output.
There are multiple other challenges. Where do you put the dryer? Or whatever they call the part that sits in front of the radiator of the car? It's usually pretty big, about the same area as the radiator. Air has to pass through it pretty quickly; that's why the car's cooling fan is programmed to turn on whenever the A/C is running.
The BIG challenge, though, is that the A/C is usually integrated in to the car's powertrain control module (the engine computer). "Weaning" it from the PCM, to run on some mechanical control, would be a project.
One thing I've seen -- I am NOT making this up -- some folks with old beater cars have come up with "ghetto" A/C units using -- don't laugh -- Igloo-type coolers full of ice or those gel ice packs, and fans. You cut an opening in the lid of the cooler and mount one or two of those 12VDC fans like you see in desktop computers (they make bigger ones, too), and wire it to the car's electrical system. I know this sounds totally "you might be a redneck if....", but it's been done, and apparently it's pretty effective.
ampsucker
Platinum Member
blowing warm air over cold ice is a variation of a swamp cooler which blows warm air over water which cools as it evaporates. these types of systems work best in extremely dry climates where the relative humidity is very very low (think desert). in a humid environment, a large percentage of the perceived cooling (latent cooling) is done by drying the air relative to the ambient humidity. swamp coolers (and melting ice without a heat exchanger) beside being a very inefficient way to cool the air do nothing in helping lower the relative humidty and can actually worsen the problem by adding even more moisture to the air.
yes, it's pretty ghetto! ;-)
i would rather use a cool bandana tied around my neck then have to rig something like that up.
the "dryer" you are referring to is actually the condensor where the heat taken out by the a/c is blown up to the environment. there is a dryer component to, but it is a canister.
as mentioned in previous post, there are better (easier) and more efficient ways to do this. if nothing else, a self contained package or small window unit designed to run on DC, like the kind they use in small campers, would be a much easier install and the efficiency rating would be exponentially higher since all the engineering is already done for you.
amp
yes, it's pretty ghetto! ;-)
i would rather use a cool bandana tied around my neck then have to rig something like that up.
the "dryer" you are referring to is actually the condensor where the heat taken out by the a/c is blown up to the environment. there is a dryer component to, but it is a canister.
as mentioned in previous post, there are better (easier) and more efficient ways to do this. if nothing else, a self contained package or small window unit designed to run on DC, like the kind they use in small campers, would be a much easier install and the efficiency rating would be exponentially higher since all the engineering is already done for you.
amp
Bill Barrett
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A/C's were the car that the Cobra was made from.
sandman2234
Super Member
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I studied a little bit of A/C in school back in the mid 70's for automobiles and a little more for house types in the 80's.
From what I know, running it off the pto is possible but something to consider about using a "junkyard system" is the concern that the system has been sitting open for X amount of time, possibly being damaged in an accident. Any leakage will allow the system to discharge and when it is empty, the system then pulls in air, which contains moisture. The moisture is the systems worse enemy and even if you catch the car right after it hits the yard, the moisture still has to be removed. The way to do this is to pull a vacumun on the system and hold it for extended periods of time. Worse case you may need to hold a vacumun on it for up to 24 hours. As far as running it off the pto, my question is why? Seems mounting a small compressor on a bracket and running it off the engine to get the added speed required for a compressor would be less trouble than having to mount a pulley on the pto and running fan belts to speed it up to compressor speeds. What happens when you need to run a bush hog or other pto attachment, and it is 95 degrees outside? Just removing the compressor by swinging it out of the way is a pain, but still doable.
David from jax
From what I know, running it off the pto is possible but something to consider about using a "junkyard system" is the concern that the system has been sitting open for X amount of time, possibly being damaged in an accident. Any leakage will allow the system to discharge and when it is empty, the system then pulls in air, which contains moisture. The moisture is the systems worse enemy and even if you catch the car right after it hits the yard, the moisture still has to be removed. The way to do this is to pull a vacumun on the system and hold it for extended periods of time. Worse case you may need to hold a vacumun on it for up to 24 hours. As far as running it off the pto, my question is why? Seems mounting a small compressor on a bracket and running it off the engine to get the added speed required for a compressor would be less trouble than having to mount a pulley on the pto and running fan belts to speed it up to compressor speeds. What happens when you need to run a bush hog or other pto attachment, and it is 95 degrees outside? Just removing the compressor by swinging it out of the way is a pain, but still doable.
David from jax
workinallthetime
Veteran Member
I think your biggest problem would be finding a junkyard a/c unit you could use that was in good enough shape to bring back to life.
You would need the system to use r134 unless you plan on going to mexico to get some r12.
some things you would neeed,
compressor, acumulator, lines, orfice, condensor, control unit, pressure switches, oil and leak die.
here is a short description,
(1)A/C Compressor(2)A/C Condenser(3)A/C Evaporator(4)A/C Accumulator(5)A/C Low Pressure Switch(6)Dessicant Bag(7)Oil Bleed Hole(8)A/C Condenser Orifice
The cycling clutch orifice tube (CCOT) refrigerant system cycles a compressor (1) on and off in order to maintain the desired cooling. This cycling also prevents evaporator freeze-up. The temperature selector on the control assembly maintains comfort in the passenger compartment comfort.
A switch that senses low side pressure as an indicator of the evaporator pressure controls the refrigeration cycle, or the on and off operation of the compressor. The cycling pressure switch is the freeze protection device in the system. The switch also senses refrigerant pressure on the suction side of the system. This switch is located on a standard service low-side fitting. With air temperatures of 16-26ｰC (60-80ｰF), the increased pressures within the charged air conditioning system closes the contacts of the pressure switch.
When an air conditioning mode is selected, the compressor clutch coil receives electrical energy. As the compressor reduces the evaporator pressure to approximately 175 kPa (25 psi), the pressure switch opens, de-energizing the compressor clutch. The system moves towards equalization and the pressure reaches approximately 315 kPa (46 psi). Then, the pressure switch contacts close, telling the PCM to recognize the clutch relay. The cycling continues and maintains the evaporator surface temperature at approximately 7ｰC (45ｰF) depending on ambient and relative humidity. Higher ambient temperature and higher humidity equal higher discharge temperature.
Some slight increases and decreases of engine speed/power may occur under certain conditions, due to the cycling. This is normal. The system cycles in order to maintain maximum cooling, without evaporator freeze-up.
Additional compressor protection results from the operating characteristics of the low-side cycling pressure system. If a massive discharge occurs in the low side of the system, or the orifice tube becomes plugged, the contacts of the pressure switch may not close due to insufficient low-side pressures. If there is a low charge, insufficient cooling accompanied by rapid compressor clutch cycling is noticeable at high air temperatures.
When the engine is OFF while the air conditioning system is operating, the refrigerant in the system flows from the high-pressure side of the expansion tube (orifice) to the low pressure side until the pressure moves towards equalization. This may be detected as a hissing sound for 30-60 seconds. The hissing is normal.
The air conditioning systems available for the vehicle are the following:
You would need the system to use r134 unless you plan on going to mexico to get some r12.
some things you would neeed,
compressor, acumulator, lines, orfice, condensor, control unit, pressure switches, oil and leak die.
here is a short description,
(1)A/C Compressor(2)A/C Condenser(3)A/C Evaporator(4)A/C Accumulator(5)A/C Low Pressure Switch(6)Dessicant Bag(7)Oil Bleed Hole(8)A/C Condenser Orifice
The cycling clutch orifice tube (CCOT) refrigerant system cycles a compressor (1) on and off in order to maintain the desired cooling. This cycling also prevents evaporator freeze-up. The temperature selector on the control assembly maintains comfort in the passenger compartment comfort.
A switch that senses low side pressure as an indicator of the evaporator pressure controls the refrigeration cycle, or the on and off operation of the compressor. The cycling pressure switch is the freeze protection device in the system. The switch also senses refrigerant pressure on the suction side of the system. This switch is located on a standard service low-side fitting. With air temperatures of 16-26ｰC (60-80ｰF), the increased pressures within the charged air conditioning system closes the contacts of the pressure switch.
When an air conditioning mode is selected, the compressor clutch coil receives electrical energy. As the compressor reduces the evaporator pressure to approximately 175 kPa (25 psi), the pressure switch opens, de-energizing the compressor clutch. The system moves towards equalization and the pressure reaches approximately 315 kPa (46 psi). Then, the pressure switch contacts close, telling the PCM to recognize the clutch relay. The cycling continues and maintains the evaporator surface temperature at approximately 7ｰC (45ｰF) depending on ambient and relative humidity. Higher ambient temperature and higher humidity equal higher discharge temperature.
Some slight increases and decreases of engine speed/power may occur under certain conditions, due to the cycling. This is normal. The system cycles in order to maintain maximum cooling, without evaporator freeze-up.
Additional compressor protection results from the operating characteristics of the low-side cycling pressure system. If a massive discharge occurs in the low side of the system, or the orifice tube becomes plugged, the contacts of the pressure switch may not close due to insufficient low-side pressures. If there is a low charge, insufficient cooling accompanied by rapid compressor clutch cycling is noticeable at high air temperatures.
When the engine is OFF while the air conditioning system is operating, the refrigerant in the system flows from the high-pressure side of the expansion tube (orifice) to the low pressure side until the pressure moves towards equalization. This may be detected as a hissing sound for 30-60 seconds. The hissing is normal.
The air conditioning systems available for the vehicle are the following:
?nbsp;C60 Front Manual Controls, HVAC System
?nbsp;C69 Rear, HVAC System
?nbsp;C69 Rear, HVAC System
KevPH1
Silver Member
Any thoughts of using one of the roof mounted (RV) A/C units?
Mounting the compressor to the engine maybe the toughest part.
You can buy custom made A/C hoses from most larger suppliers.
Last, a super-duty cage, or box, to protect the roof mounted unit!!
Any A/C system open,or leaked empty will draw moisture.
This moisture will change into an acid if not completely removed.
The acid will destroy the A/C unit from the inside!
Good luck!
Mounting the compressor to the engine maybe the toughest part.
You can buy custom made A/C hoses from most larger suppliers.
Last, a super-duty cage, or box, to protect the roof mounted unit!!
Any A/C system open,or leaked empty will draw moisture.
This moisture will change into an acid if not completely removed.
The acid will destroy the A/C unit from the inside!
Good luck!
DavidVT
Gold Member
Anything is possible given time and money.....
Maybe if you could find an RV roof AC unit that still worked (no gas lines open to the atmosphere and still capable of cooling), if that that unit has modern freon that you can replace from today's parts stores, if you can bring yourself up to speed on all the compenents and their relationships, and you can then mount the compressor and condensor in a place that makes sense and provides the right air cooling and rotational speed, then maybe you might be on to something.
I respect everyone here who makes things out of stuff. It is not always about the most cost effective way but it is all still pretty 'cool'....
For my .02, I think I would also investigate a cheapo house window airconditioner and what it would take to make that run on your tractor along with sealing up the cab as we know a house AC is much smaller than a vehicle unit. Maybe they are too fragile and maybe the startup current is to great for big inverters but maybe???
Or find a used tractor place and look for an existing solution??
I sometimes work with AC units that were designed for trains, buses, etc. The condensor units have DC electric fans that change velocity as the pressure changes. The evaporator unit (inside the vehicle) is very simple with a DC fan behind the coil and a simple high low fan and hot/cold dial knob. The auto style compressor is run off a belt to the main engine with a standard electric clutch assy. I think they are made by Konvectra (sp?) and my usage is in R&D mobile stuff. Crazy expensive new, so don't look to buy one from the factory...
Simple systems like this still exist and are made but moving that to a tractor might be a non-trivial task.
Maybe if you could find an RV roof AC unit that still worked (no gas lines open to the atmosphere and still capable of cooling), if that that unit has modern freon that you can replace from today's parts stores, if you can bring yourself up to speed on all the compenents and their relationships, and you can then mount the compressor and condensor in a place that makes sense and provides the right air cooling and rotational speed, then maybe you might be on to something.
I respect everyone here who makes things out of stuff. It is not always about the most cost effective way but it is all still pretty 'cool'....
For my .02, I think I would also investigate a cheapo house window airconditioner and what it would take to make that run on your tractor along with sealing up the cab as we know a house AC is much smaller than a vehicle unit. Maybe they are too fragile and maybe the startup current is to great for big inverters but maybe???
Or find a used tractor place and look for an existing solution??
I sometimes work with AC units that were designed for trains, buses, etc. The condensor units have DC electric fans that change velocity as the pressure changes. The evaporator unit (inside the vehicle) is very simple with a DC fan behind the coil and a simple high low fan and hot/cold dial knob. The auto style compressor is run off a belt to the main engine with a standard electric clutch assy. I think they are made by Konvectra (sp?) and my usage is in R&D mobile stuff. Crazy expensive new, so don't look to buy one from the factory...
Simple systems like this still exist and are made but moving that to a tractor might be a non-trivial task.
patrick_g
Elite Member
We seem to be overlooking the fact that he is on an open tractor with just a sun shade roof!
Air conditioners circulate the same air through the evaporator coils over and over to dehumidify and cool the air. A single pass is going to be MUCH LESS EFFECTIVE. If the RH (relative humidity) is low then there are lots of possibilities, including a "swamp" cooler approach. With low RH a wet bandana or a misting system would work miracles. With high RH you can forget misting, cool handkerchiefs and such.
The problem is the OPEN WORK STATION. Running single pass air onto you in an open tractor will not do much, certainly a lousy return for the effort invested. Want to test this? Drive 60-70 MPH with all your windows open and ask the back seat passengers how cool the A/C feels. Even front seat passengers may not be helped noticeably.
I once built a prototype hot/cold therapy machine, originally intended for use on thoroughbred horses but later marketed to the San Diego Chargers football team and as a medial apparatus for both hot and cold therapy on human patients.
Your comfort depends on many factors. Net heat loss/gain can be a large factor. If you sit down on a cool concrete bench even though the air may be 100F it will cool you off by conduction. The concrete can take up considerable heat. No, I don't recommend a concrete seat for the tractor.
Here is the deal. A small refrigeration compressor is plumbed to neoprene tubing for the evaporator instead of copper tubing in a finned heat exchanger (evaporator.) The neoprene tubing is glued to neoprene foam "wet suit" material in a pattern like in-floor hydronic tubing is put in a slab. This is fashioned into seat covers for the tractor. When you sit on the seat you will loose body heat into the seat. and it will cool your entire body due to the effect of blood flow. If you want to do more you can make up a couple "arm covers" like shirt sleeves which can wrap around your upper arms and fasten with Velcro. This can suck a lot of heat out of your body. You will have to be careful to not overdo it and chill yourself too much.
I personally think the "cool seat" would do enough and would be more convenient for getting in and out of the tractor while working. Arm and or leg covers would be fine for long sessions as adjuncts to the cool seat. They would allow more surface to be involved so cooling could be more moderate for the same net effect but if you have to get on and off a lot it would be a bit of a nuisance but not too bad with Velcro fastenings.
Do exercise caution as this is a very effective cooling system and you can chill your flesh too much. When I built the prototypes of this system I designed and built a thermostat that operated off the skin temperature of the patient and cycled the unit on and off to maintain that temp.
If you build this system, consider using a reversible heat pump so you can heat the seat in winter with very little extra cost.
Pat
Air conditioners circulate the same air through the evaporator coils over and over to dehumidify and cool the air. A single pass is going to be MUCH LESS EFFECTIVE. If the RH (relative humidity) is low then there are lots of possibilities, including a "swamp" cooler approach. With low RH a wet bandana or a misting system would work miracles. With high RH you can forget misting, cool handkerchiefs and such.
The problem is the OPEN WORK STATION. Running single pass air onto you in an open tractor will not do much, certainly a lousy return for the effort invested. Want to test this? Drive 60-70 MPH with all your windows open and ask the back seat passengers how cool the A/C feels. Even front seat passengers may not be helped noticeably.
I once built a prototype hot/cold therapy machine, originally intended for use on thoroughbred horses but later marketed to the San Diego Chargers football team and as a medial apparatus for both hot and cold therapy on human patients.
Your comfort depends on many factors. Net heat loss/gain can be a large factor. If you sit down on a cool concrete bench even though the air may be 100F it will cool you off by conduction. The concrete can take up considerable heat. No, I don't recommend a concrete seat for the tractor.
Here is the deal. A small refrigeration compressor is plumbed to neoprene tubing for the evaporator instead of copper tubing in a finned heat exchanger (evaporator.) The neoprene tubing is glued to neoprene foam "wet suit" material in a pattern like in-floor hydronic tubing is put in a slab. This is fashioned into seat covers for the tractor. When you sit on the seat you will loose body heat into the seat. and it will cool your entire body due to the effect of blood flow. If you want to do more you can make up a couple "arm covers" like shirt sleeves which can wrap around your upper arms and fasten with Velcro. This can suck a lot of heat out of your body. You will have to be careful to not overdo it and chill yourself too much.
I personally think the "cool seat" would do enough and would be more convenient for getting in and out of the tractor while working. Arm and or leg covers would be fine for long sessions as adjuncts to the cool seat. They would allow more surface to be involved so cooling could be more moderate for the same net effect but if you have to get on and off a lot it would be a bit of a nuisance but not too bad with Velcro fastenings.
Do exercise caution as this is a very effective cooling system and you can chill your flesh too much. When I built the prototypes of this system I designed and built a thermostat that operated off the skin temperature of the patient and cycled the unit on and off to maintain that temp.
If you build this system, consider using a reversible heat pump so you can heat the seat in winter with very little extra cost.
Pat
