A cheaper more primitive a/c system
 

I have an '83 300sd that i bought for $300. It runs great, 80 mph, 30 mpg, on WVO. I use it to commute about 4hrs each week. The a/c compressor is shot and I don't want to spend more money than I paid for the car to fix it.
This is the plan:

Remove compressor for weight and remove condenser to alow better engine cooling.
Fill a cooler full of ice water in the front floor board, submerge a 12vdc marine bilge pump($16) into the water and pump water thru my evaporator and back into the cooler. The fan blowing across the evap should cool the car down. Does anyone see a problem with my plan?

I figure I can buy alot of ice for what a complete a/c sys. fix would cost.

I need to know where the best place to tap into the system for the in and out ports of the evaporator. Would it be at the exp. valve? If so which ports?

I'd at least try to find out what's wrong with the system first. It could be a simple fix!

-Jason

You're going around the world for nothing. Cheap $16 bildge pumps aren't meant to run continuously so that is $16 thrown in the trash.

A really cheap air conditioning system is the 460 which came standard on all Mercedes diesels - ie 4 windows down, 60 mph.

Take the money you saved on the car & fix your AC. Or...take your time researching and you won't need AC because it will be winter. Perhaps begin with the heater threads to move ahead of the curve.

Yeah, A/C work really isn't that hard or expensive (if you do it yourself) and you should be able to find a compressor in the junkyard for pretty cheap. I actually have a spare compressor, I just don't know if it works.

If the A/C system holds 150 psi, and you are getting 12 volts to the compressor and your blower is blowing, then you can fix it awesome for about what you paid for it.


get a NEW compressor (150$ at Mcparts online after 50$ off) if fastlane is moving compressors now, feel free to delete. I couldn't find any when I searched.

Get a reciever dryer (20$)

Have your indy ac guy install compressor purge with nitrogen, install dryer with oil, pull vacuum. 3.3lbs of r12 (or 2.8ish lbs of 134) and fire it up.

AC guys (vstech specifically as everything I know about ac I'm pretty sure he taught me) feel free to complete what I am missing.

I should have stated previously that the compressor is shot. Jumpered the pressure switch and the clutch does not engage.
(so that is whats wrong with the system, its not a simple fix)

Junkman, actually bilge pumps are made to run continous, ask anybody who knows anything about boats. The are made to pump rain water out of a boat all night long. Or until the batt runs down! So 4hrs of running should be a breeze for a pump.

Thayer, I have just rebuilt the a/c system on my son's '81 300sd for $350 for compressor, rec/dry,exp valve, and 609 cert. Its r12 and its cold.

I also restored my daughter's '85 300d, which is 134 and not near as cold.

I spent a day of my life and $60 on refridge restoring a sys with a used compressor that ran for about 10 minutes, so the one thing I know about a/c systems is ....NEVER INSTALL A USED COMPRESSOR!!!!!!!

I am going to try it, my main concern is the evap was made for gas and I'm pumping water thru it.....may be a problem.

Is the exp valve the best place to tap into the lines for IN and OUT of evap? Anyone

Your project is interesting and it would work but I believe there is one problem you are overlooking. The simple law of energy A consequence of this law is that energy can neither be created nor destroyed, it can only be transformed from one state to another and you can't get more energy out of something that wasn't there to begin with.

You are probably looking at 20 pounds of ice per hour to make this work effectively.

Don't take this personally, but I hear the theme to Sanford and Son playing...

What would be neat is if we could drop in a totally electric system, like a household set up. I know we would need to have a beefier alternator, etc.

I wonder if they even make a 12 volt compressors that would work?

You seem to be an expert with all the systems you have "restored" but. A clutch not engaging does not mean the compressor is shot but thats ok. Energy transfer/time/ and available energy in ice is the problem with your proposed system. Hint, AC systems are rated in tons. Tons of ice and the energy required to melt a ton of ice. Next hint heat transfer takes time. Your proposal to blow warm air over a "luke cool" say 40 degrees evaparator will net you maybe a degree in cooling. so you take 90 degree air and cool it to 89 degrees. But that is an improvement. With that said.....go for it. If I'm wrong and the laws of thermodynamics have changed you may hit it big. Start working on the heater. Thanks

I was looking at a 1930's era Dodge that had "A/C" It had the air scoop in front, by the windshield, and in the cabin, was a dry ice compartment, that the air flow was directed over. Neat innovation, but I do not see how that would last very long, and the car had to be moving to get air flow, since there was no fan.

Yes, we use them on our electric buses.

Hey, if you are that into it....TAKE PICTURES. The Expansion valve is the "in" to the evap. Not sure where the return is. If this works, I will be impressed.

They may be other methods besides ice to fuel coldness into the evap. Dry ice like the above mentioned. there is also a chance you could dissassemble a dorm size refridgerator with a beefy alternator to supply coldness, maybe even power it by the use of a constantly charging battery and an amp style capacitor for initial fire up.

http://www.certifiedmastertech.com/wordpress/wp-content/uploads/2009/03/automobile-air-conditioning-diagram-233x300.jpg

according to that pic, follow the low side back into the dash and you will find your "out"

"Great spirits have always encounter violent opposition from mediocre minds"

This is not the first time Ive been called Fred Sanford. I think about it when I'm cruising down 75 South @ 85mph in a $300 Benz burning straight gease that I collect and filter in my garage....

I'm not creating or destroying energy....I'm changing a solid to a liquid in a 4 hr time span. I took Physics also.

An EXPERT.... Thanks for the complement...

Tons of Ice? Really, Ever took a cooler camping? 2 bags of ice stay cold for 2 days. Now I know blowing air over the cold water will speed up the process and so I may need 4 bags.


Whether you think it will work doesn't matter, I'm doing it. Just need to know if anyone knows the shortest route in and out of the evaporator....ANYONE? any free thinkers?

You will have to do some line cutting to get the the evaporator, or use the fittings where the exp valve is.

What is the current draw on those?

Cannot Wait for the "Performance" figures for this system.
 

As Requested:
Picture of replacement Behr evaporator (Without exp valve)

[This ill advised train wreck will provide hours of amusement to us all.]

Wouldn't the most straightforward way be to simply cut the existing "high side" and "low side" lines going into the evaporator, and plumb those lines into your cooler & pump apparatus?

The goal is to exchange as much heat (energy) as possible between the moving air and the cold water. My concern is that the evaporator/cold water design will not have enough heat capacity to effectively cool the cabin of your automobile.

You would probably want a larger surface area (i.e. a motorcycle radiator) built into a sheetmetal box which you could pop-rivet to the face of your dashboard.

SteveM.

Quickest way in would be to remove the expansion valve and plumb it there. My concern would be the amount of humidity in the vehicle. Your A/C evaporator also de-humidifies the air in the vehicle. I guess if the evaporator got cold enough it would sweat and then the condensate would drain out the drain holes in the tunnel. Interesting idea and would love to follow this along. Take some pictures and keep us informed.
You know, in the old days they made "swamp coolers" for VW Beetles that hung on the passenger side window. I believe they used ice also.

Since you took Physics you will find it easy to understand that ice kept in an enclosed and insulated container designed to PREVENT heat loss will melt at a slower rate than when used for the express purpose of REMOVING heat from the cabin.

You say that the compressor is "shot." What diagnosis brought you to this conclusion?

Here we go again...

Free thinker with flame suit on here.

Since this is a $300 car and you are not inclined to spend money on it...

Why don't you cut a hole through the firewall, run your hoses through that, and use the in/out for the heater core instead? Then you can leave the A/C system intact should you decide to repair it later.

As for those people saying the A/C system should be fixed, what if the evaporator has a leak? Would you really pull the dash out in the August heat to fix this thing?

You don't even have to cut a hole in the firewall, use the main wiring harness rubber plug that is on the firewall behind the glovebox.

I'm not criticizing your idea at all. Actually it's interesting and fun.
But, I don't think it will work very well at all and definitely not for very long. You are going to be blowing large quantities of 90+* air across the coil and it will warm things up in a hurry, necessitating frequent ice replenishment. Also the rate of heat transfer will be inadequate to produce comfortable vent temperatures. I do think you would have some dehumidification benefits as long as the temp of the circulating water was below the dew point. And, to be fair and open-minded, even if you got a vent temp of 65-70 there would be some comfort in that.
I say go for it. Can't hurt a thing and costs very little. And I could be totally wrong about the whole thing.:D

As far as original ac capability, there are two variables we do not know. The BTU capacity of the condensor and that of the evaporator. IIRC the capacity of the R4 pump is around 30000 BTU. There are 12v hermetically sealed pumps, but I have found none that approach the BTU capability of the old belt driven pump. Working with a pump that is at the voltage that the caes system is at is the most efficient. Using inverters to raise the voltage introduces huge losses. Consider this, a typical window ac unit for a room in a house is somewhere around 1500 btu (small room) and consumes roughly 1300 watts of energy. Two major differences between a room and your car are insulation and the amount/location of the glass. A car needs a considerably higher capacity ac system to make up for these losses. There are also solid state (peltier) ac "condensors", but again the energy required to drive them exceeds what the stock pump would consume, not even taking into account the losses converting mechanical energy (rotation of the engine) to electrical energy (alternator). I looked into using both of the above mentioned options before purchasing the new r4 pump that is in the vehicle now. Having presented those options, I simply don't believe there is enough btu calacity in the ice to keep up for an extended amount of time. On the other hand if you want to experiment, do so its how we learn. Keep in mind how expensive the ac parts are that are in the car and that they may be destroyed ultimately costing you more money than a clutch coil or ac compressor would have. . Just my free advice, take it for what its worth.

Best of luck,
Nick

This isn't rocket surgery, guys. Melting one pound of ice requires about 700 BTUs of energy. You can decide how many pounds of ice it will take to keep the car cool for a specific amount of time.

I like the heater core idea much better than the evaporator. It's designed for air to liquid heat transfer instead of air to gas.

Ditto, you're gonna need a lot of ice. Not practical. May I suggest an alternate method. Take the ice water, pump it through a misting nozzle and have it spray it all over your body. Wear a bathing suit. :D

This is entertaining, but there are only two usefull answers; fix the AC or open the windows.

Actually, putting a mister behind a fan would work quite nicely. If you wore a bathing suit while you drove with the windows down you'd get a nice tan too! :cool:

-J

Better check your numbers. I'm noy knocking the idea or open thinking but ignoring heat transfer and physics to rationalize and idea isn't open mindedness. I still say go for it. Thanks

You're correct, I was remembering incorrectly, it's actually 143 BTU/lb. at 32F. My point was the OP could calculate how much ice would be required and draw his own conclusions if it's practical.

Even simpler ---- open the top of your cooler and let a 12v fan ($10) blow across the ice onto you. Too, you could put some of the ice cubes in baggies and place them in your lap.

http://www.arcticaircooler.com/

Same general idea. A few companies make these things and people buy them.

From the articaircooler site FAQ's:

HOW MUCH ICE PER HOUR DOES THE UNIT USE?
It is hard to say because of so many variables, but approximately 8 to 10 lbs. per hour would be reasonable.

225 AH @ 18,000 BTU
R410a
Ceramic brushless motors.

I also think the heater core would work better. It was designed for water to air. The evap core has a small input and a large output and not designed for a liquid. Best idea is shown in a picture hanging on our shop wall. It shows a window unit a/c mounted in the right front window and a motor/generator mounted on the trunk lid. ;);););)
Paul

Sounds like an excellent plan Mr Goldberg. Please post pictures when you're done!

Might not fit your budget....but
 

You might want to install a portable ice maker in the passenger seat area. Then you could replenish your melting ice. Here's one 12 volt ice maker I found at:
http://www.cmacma.com/cmacma_technologies_files/ice/ic-1.htm

PORTABLE 12/24 VOLT ICE MAKER

MODEL NUMBER: AST-IC-1 $ 880.00 Plus Shipping


"Available in 12 Volt, 24 Volt and AC/DC configurations."

Make ice cubes anytime. Ideal for home, vehicle, bus, RV, Over-the-Road Big Rigs, and Solar. Just plug into a 12 Volt Source and add water. Starts making ice in 10 to 15 minutes. Comes with a cigarette Lighter plug to easily install in any vehicle or marine craft.

• Uses Tap Water or Bottled Water
• Environmental friendly R-134a Refrigerant utilized.
• Portable Ice Maker makes Ice cubes anytime, no Installation required
• Easy to Use and Fully Automatic, just add water
• Compact design
• Free Standing unit, or can be built-in.
• Light Weight. (Only 50 Lbs)
• Insulated Storage Compartment
• Easy Ice Cube Removal
• Makes 3-Different Sized Ice Cubes
• Makes up to 29 Pounds of Ice per day
• Stores up to 2-1/2 pounds of Ice
• Proven Danfoss Compressor unit with State of the Art Micro-processor Electronic Controller,
• Configured to operate on 12 Volts DC or 24 Volts DC automatically. Can also be configured to switch between standard 120 Volts AC Operation and DC as an option.
• 4.0 Amps @ 12 VDC (When compressor is running)
• Sealed System. Electronics, and Compressor warranted for a full 5-years.
• Dimensions: 16-1/4" x 15-1/2" x 14" (HxDxW)

When I was a kid in Phoenix we had one of those cylindrical evaporative coolers on our Pontiac. You rolled the passenger window up on it and the cylinder hung outside. It had a fan in the front that blew outside air over water or ice to cool it and the cooled air came into thru a vent that came down the side. It was speed operated. If I remember correctly it would melt ice in only a few minutes and hard left turns often yielded a nice cool lapful of water for anyone who happened to be sitting in the passenger seat. Wonder if somebody still makes those or if an antique version could be refurbed?
I'm no physicist, but I live where it's hot. You're gonna need tons of ice. I can't wait to see how this project turns out.

Oh so interesting, you crazy free thinkers. Here are my $.02. Why not create a cooling jacket - just like your engine has. Perhaps like two wet suits that you seal together to create one suit containing an inner cavity - then you can use your cooler full of ice water and bilge pump to pump water into and out of your own personal water cooled jacket. I mean, why waste all that energy on the stupid air that is going to rush right out as soon as you open the door. Unless you are trying to offset global warming, but let's not go there.

Damn . . . a google search reveals that someone beat me to the idea: http://www.trendhunter.com/trends/liquid-cooled-clothing-the-cool-shirt

I say try this first. Start a new trend - driving shirts - get a cool pair of racing gloves to go with it. In the winter time you run hot chocolate through this thing and install a spigot near your mouth. There I go again, giving away all my good ideas.

Those actually work pretty good. A lot of the outside bars down here use them. You dont really "get wet" unless you are right in front of it. The mist is so fine you can barely see it. But, it does make a noticeable difference.

This is a little ridiculous though IMO. If the car is just a beater, paint your roof with some white "bed liner material" and leave the windows down.

Just putting a 10lb. bag of ice in a cheap cooler will melt it all away in a couple hours (down here). Start putting more heat into the ice and I"m betting it would all be gone in a matter of minutes. Especially if we are talking about a car that has been out in the sun and is already "heat soaked".

Some factory car A/C systems from the 1950s are trunk mounted, so I suggest this route. All you would need to do is go to Harbor Freight and buy an inverter and 16 foot extension cord. First, cut a square in the spare tire well and mount an old A/C window unit there, condenser side down. Hook up the inverter to your battery and run the extension cord through the firewall, connect the trunk unit. Now, you could remove the parcel tray for unobstructed air conditioning from the trunk. Another idea is removing the window unit's evaporator, and running lines from the window unit to the Mercedes evaporator for factory A/C performance and feel. Should work better than a R-134a conversion. Good luck.

Blackhawk helicopter uses a system like that for the pilots. It is a vest worn close to the body with a connection for the cooling unit. The unit runs freon through the vest to cool your core body temp. maintenance nightmare.

Your typically not hot in an aircraft that is 4000 ft off the ground but helicopters, in a war zone mind you, fly low where the heat is.

"Great spirits have always encounter violent opposition from mediocre minds"

Confucius died, like 2K years ago

That sir, is incorrect. Ask anyone that has owned a boat for many years. Normally the pump is run to clear the bilge & is not used for a while. I suggest you search on "why boats sink at the dock". The cheap bilge pumps crap out - hopefully not when you need them in an emergency situation.

Nice idea but i submit that implementing will be akin to urinating off the high side (of the boat - not compressor).

it seems like he'd rather spend nickel and dime to buy 2 bags of ice on every summer day that he'll drive his $300 car @ 85mph for 2 hours on a veggie than spend a little more to fix the system properly

I'm thinking coffee would be so much better and could even be endured the first couple of miles in the summer.

The quote is from Albert Einstein

Yes, I have one of these things that someone gave to me. I was amazed when I saw them go for over $200 at the swap meet.