Engine-Driven AC for driving around in
my '62 Crown bus, soon to be a "cool" Crown bus...
(Click on the photos for bigger ones)
Since using the roof airs while driving turned out to be a pain... the air never aims where you want it when you're driving, it uses up propane and the genset isn't all that happy running while driving, etc, I decided to do it "right" and create an engine driven AC for on the road use. That plus my original Crown heater, defroster, etc had to go because it was clunky, noisy, the radiator leaked, etc... I decided to find a completely new heater/defroster/AC unit to mount up front, with some nice ducting and vents for the driver and passenger. My observance while driving my van is that it's not as important to have the whole cabin cool as it is to be able to aim cold air at my body, so the addition of aimable vents was a big deciding factor.
I ended up buying a combo heater/AC/Defrost unit from RonTheBusNut, and it fit perfectly... like it was designed for my bus!! So after a few hookups and a nice new screen grille (which left a very nice spot for the stereo/DVD player) it was all mounted and at least the heater and defrosters now work quietly and very nicely.
This first photo shows the cores mounted in the hole where the origional bus heater had been. The defroster unit turned out to be a separate piece (Ronthebusnuts photos are horrible! I thought it was all one when I first called him) and is mounted vertically on the right side. The hoses come in from underneath; under just in front of where the green tape measure is there is another big cavity that houses the hoses, valves, condensation drain hose, etc.
To the left of the defroster is the AC core with it's hoses... the black ones are freon and the red ones are the hot water. (only the freon supply hose is installed as of this picture... the return hose also screws into the little square aluminum expansion valve block shown in front of the core, but I hadn't installed it yet)
The air ducting hoses come out of the rear, and I had to modify the hose-flange plate to get rid of all the exit holes but four..I think it came with provisions for 8 outlets.
Three go to my dash and the fourth can be seen sneeking out near the throttle pedal. I like this one 'cause it keeps my feet and legs cool or warm (as necessary) as I drive.
Photo #2 shows the same scene but from a bit farther back, so you can get a perspective of it all. You can see the three dash vents and the driver's "leg" vent a lot better.
This photo shows the setup with the grille installed. The grill was something I folded up out of a piece of perforated steel sheet, with cutouts for the controls and that last hole which now houses my CD/DVD player. The perforated metal is the perfect solution for the problem of what to do for "return" air... with a perforated panel it instantly becomes a non-issue. In the photo you can see the "guts" through the perforations... I ended up later hitting them with a can of black spray paint and they all dissappeared instantly from view!
Now for the harder part, the AC compressor, condenser, hoses, etc.
I had quite a few conversations with fellow busnuts Mallie and Chuck Lott, both of which gave me very helpful hints on how to do the system. Since I'm no expert on AC stuff, I finally came up with this drawing of how I thought things should probably go-
In the end I ended up finding a guy on ebay who calls himself ebay's air conditioning specialist. His name's Gus, goes by
"ACProGus"
on ebay... a very nice individual. I went to his website and discovered that in addition to being an AC specialist, he also seems to love beautiful women, so I figured he ain't all bad.
He sells lots of A/C parts at good deals on ebay, and also directly if you email him.
After a few very informative emails from him, the drawing now changed and became somewhat simpler:
I bought a Sanden compressor from him (a heavy duty model, SD-510) as well as a dryer, a few hoses and fittings and a condenser, all for about $300.
Here is an EXCELLENT page on Sanden compressors from RVparts.com , explaining the type numbers and options for these compressors
The condenser fit into my radiator area like a glove. I made up four brackets for it out of 1" x 1/8" strap steel, and *carefully* undid four of the radiator tank bolts to slip in the brackets.
Next problem, how/where to mount the compressor. Looking at first glance it's an impossible task, because there jes' aint no room down there in the Crown's engine compartment, and no pulleys left over to drive anything extra. So I looked and thought, and finally decided this: The power steering system has a lonely vane pump running on it's own belt. That is about the one and only belt that sees little use (only while wrestling around corners in the city) and if it breaks is no big deal as compared to breaking a compressor or water pump belt... so I figured that if any belt was able to take the added load of the AC compressor and not add any safety issues for either myself or the bus engine, that was the one.
I figured if I could machine up a dual pulley for the steering pump and use it as sort-of a jackshaft, and find an AC compressor that would work turning backwards from the norm, I could mount the compressor next to the steering pump facing toward the rear of the bus (almost exactly face-to-face with the alternator) on a mounting plate sandwiched between the steering pump and it's mount, and drive the compressor from there with a second small belt.
Taking all the measuerments, it looked like it would work fine.
I emailed Gus, and he verified that what I had been told by Chuck was true, that Sanden SD-5xx series compressors can work while rotating either direction without any problem, so that meant my scheme would work!
I started by drawing up the pulley and machining it out of a hunk of 4" solid steel bar stock. The way it works is that it's main groove is 1/2" farther away from the pump than was the original, making up for the new compressor's 1/2" mounting plate thickness. In addition, there is now room on it to include a second smaller width pulley that matches the compressor, to drive it.
Talk about masochism...it took me 5 hours straight to machine the thing but it came out perfectly. I won't build any of you guys one of these but here's all the dimensions and some photos in case you want to. (I'm real proud of it!!!) I probably could have made it out of aluminum and saved myself a ton of work, but the thought of using a material that might actually wear down in a quarter million miles made me stick to steel... fruitless efforts considering the actual mileage I'll probably drive the bus, but at least the pulley will last a long time as I hope the bus does. The last pulley was steel and 40 years old, and definitely showing signs of wear!!
The compressor is mounted on a piece of 1/2" thick steel plate that I bandsawed out of a piece of flat stock. One side of the plate sandwiches inbetween the steering pump and it's original Crown mounting plate. The compressor bolts in three places to the other side, two of the bolts are slots allowing for belt tensioning. Not very precision but it works fine.
Here it is just prior to my reassembling the steering pump (see below) and how it all bolts in:
(kinda tough to photograph beacuse there is so little room down there to get a good angle)
Here's the FINAL done installation with belts and all
STEERING PUMP
The steering pump is shown in these photos taken apart, because it was my first thought to get a newly rebuilt one since I had to remove it for this job.
The pump always made a LOT of noise. When I bought my bus the pump was totally dry, and when I put fluid in it it worked, but now being an "abused" vane pump it was louder than anything in the entire engine compartment...in Over 10,000 miles it quieted down a bit but was still nothing I cared to listen to for the rest of my life.!!
So I decided to swap it out for a new rebuilt one....until I found out that my model is frigging $1400 **rebuilt**!!! Geez!! So instead I took the thing apart, and with some carbide grit and a hard steel shaft chucked in my lathe, I lapped the insides of the vane housing to get rid of the 40 years worth of scalloping that had accumulated, bought it new bearings and seals, and put it back together. It now works at least as good as it did, and LOTS quieter!!
Someday maybe I'll find a rebuilt one on ebay or in a junkyard. But until then this one will work just fine... $1400 I am NOT going to pay someone for a silly rebuilt steering pump...!!!
Final checkout and make it go!!!
From Gus I got all the hoses, fittings, and misc. goodies that I'd need... again he came through with flying colors, sending me everything I needed and a few things I hadn't thought to order. Then there were a few extra things I had to do.... add a compressor clutch cycling switch (thermostatic) to the suction (outlet) side of the evaporator, and hook it in series with the clutch circuit, and add some additional compressor oil to the system.
I proceeded to crimp all the fittings on my hoses and put everything together. Then per Gus's instructions, I added two ounces (30cc) of extra compressor oil into the return side of the evaporator, and another two ounces of extra oil into the inlet side of the condenser.
That done, I hooked up my trusty old vacuum pump (made from a refrigeration compressor), Pulled the vacuum down on the entire system to 8mm of mercury (The A/C guys all go by inches of mercury- 8mm is equivalent to 29.6" of mercury) and kept it there for a few hours to get any water vapors out of the system. Then I disconnected the pump and watched to see if the vacuum held, signalling that the system was leak-free.
Finally, with the engine running, the compressor turning, and the cab blowers on high, it came time to charge the system. Per Gus's instructions for the temperature of the day (80) I initially put in a total of 2 pounds of R-134a. It goes slowly into the low side of the compressor as a liquid, making sure the low gauge never gets above 40-50 psi during the process. The easiest way to do this is just stick the freon can upside-down on an electronic scale, turn it on to the system, and watch as the weight changes. When it's 32 ounces less than when it started, that pretty much means that those 32 oz are in the bus now!
I then watched the system for a few minutes and called Gus. The high side pressure was about 175 and the low about 25. Gus suggested I add 2 more ounces of R134, watch and wait, and do it again if needed until the high side came up to 190 or 195. It took a total of 7-8 ounces over the initial two pounds to get there, so the system takes 40 ounces total.
In the end the pressures were as follows on my 80 degree day, 60% humidity:
The high side oscillates between 185 and 195 psi while the low side correspondingly oscillates between 17 and 20 psi. Gus confirmed that this "oscillation" is due to the expansion valve cycling.
He also said that for this system, the practical operating range should be between 180-210psi and 24-34 on the low side. The low side was lower than during my tests because the cabin got cold as I was doing the testing, thus lowering the low side to 17-20 after the system ran for an hour.
"add freon" point is if the high side is 150-160 and low is 12-16 psi...
..................
3000 miles later; two trips through death valley on really hot days...
All I did after charging the system was hop in the bus and go! The A/C system works flawlessly. On 100 degree days it keeps the cab very nice...not cold mind you, but nice. In fact I noticed that the air coming our isnt freezing as some cars are, and it's very comfortable to have aimed on you.
The only thing that has needed attention is after the first 1000 miles or so, the drive belt needed tightning.. but that's all. Otherwise it's been a reliable and no-hassle system. Quite pleasing...
ENGINE COOLING: FAN, RADIATOR, AC CONDENSER
UPDATED 2008
I've been constantly fighting my engine's cooling situation...it's edgy... Prior to installing the A/C, If driving on a hot day going up grades, it would overheat- very slowly but very definitely, and more often than I'd like I have to slow down and shift up to unload the engine until it cooled down a bit.
Because my cooling system was in perfect condition, my original guess was that this happened because the Crown's overall system simply wasn't designed for driving with it's roof a foot taller at 85 MPH on the freewway on a hot day with the AC going full blast...
Then again, I did change out the original metal blade variable-pitch fan for a 5 blade "Flex-Aire" plastic fan that I got from Chuck at West Coast Coach (it didn't work any more and ya can't get parts for it), and because I put a 2 speed clutch drive on the fan, the pulley for it is now a bit bigger than the original, slowing the fan down a bit. All combined, overheating on hot days was a reality.
...So my choices were to stick in a bigger radiator or maybe a second one somewhere...do the water squirter radiator mister thing like I did on my old bus, etc. Plus adding the A/C condenser to the equation wasn't helping much of anything.
I thought and thought and then it dawned on me... bigger fan? I called Flex aire and asked what they had that would move more air than mine. Since I had a 21" model they said I was out of luck. But I kept bugging the guy and he told me they had a 24" fan with 8 blades (three more than mine) and a lot steeper cup. So I bought one- since it's nylon I figured I could cut it down to a diameter that would fit in my shroud. I chucked it in my vertical mill with a lathe bit in the vise and turned the fan down to 22"... that was quite an operation, full blown fan runnung at 2000 RPM right out there in the open on my mill..geex, I think everything on the entire floor of my shop was picked up by the wind and hit me on the way to the ceiling!! But it worked.
I got it installed and it does definitely kick out a lot more air than the last one, so off I went on my next trip.
The fan took care of *almost* all of my concerns. The engine now ran at a nice 180 degrees 95 % of the time. But still, up at higher altitudes where the air is thin, if I hit a steep grade the temp would creep up to about 195 and settle out. Since the limit for my engine is 200, I still didn't like what was happening.
So I decided to do the next thing, a radiator mister system. Simple enough, 6-7 little drip mist heads from home Depot, a valve and some water line hooked into the house system
It took about half an hour to install, and off I went on my next trip.
It worked WONDERS! As soon as I caught the temperature rising, I'd turn on the water and poof, down it would go. It'll take the engine temp down 15 degrees within about 5 minutes even while hauling a grade. The *only* thing I don't like about it is that it uses 50 gallons of water in 300-400 miles... so... next....
As it turns out, I had a spare radiator laying around for this bus (my original that had a hole in it), and I took a close look at it. The top tank overhangs the core by two inches so there is plenty of room for more core without major mounting hassles. The overall dimensions of the radiator are 29 wide, 19 tall, 3.5 thick. Not very big.
So I found a great guy at
Discount Truck Radiators (Larry, 800.443.1322) in New York who said he could rebuild the thing with a 6" thick core at a reasonable price. I decided to do it... this way the core itself has modern shaped fins and water tubes (MUCH more efficient than the designs that were being used in the 60's) and with the added inch and a half of thickness, there's no chance that I'll ever have a cooling problem again! The misters have been removed, and when I take that next trip I'll report my success!!!
1 year later
I did change out the radiator to one with a thicker core, and it was WELL worth the trouble. But I still had a slight tendency to overheat in high deserts on a hot day towing a 5000 pound trailer. So the last ditch thing I could think of was to remove the AC condenser from in front of the radiator and relocate it somewhere else... but where?
I finally got this weird idea that I could mount it right over the front axle, in parallel with the road, and stick a giant electric fan on top of it to keep it cool. So I did it.
I hung it about 6" above the steer axle and got a big 12 volt fan out of a Crown Victoria, plopped it on the condenser so it draws air up and blows it at the floor of my bus, and hooked the fan to the compressor's 12 volts. Heh heh I won!! It works perfectly for the AC and removed that last little bit of heat and restriction from the engine radiator, and as of that moment, overheating was a thing of the past!
Wheeeee
Fun with the Crown...
