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Author Topic: OTR Drivers AC  (Read 3779 times)
Kenny
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« on: April 25, 2010, 04:43:46 PM »

Gutted the OTR main AC and heat systems. Have kept the OTR drivers heat which is working perfectly. Have also kept the OTR drivers AC evaporator. This is where my challenge comes in.

Using the OTR drivers evaporator, how would I size an automotive engine driven compressor and  condenser unit?
Is there such a thing as oversizing the compressor and/or condenser?
The condenser would be mounted in the spare tire compartment at the front.
Would use the copper lines from the original OTR AC system to transfer freon back and forth.
Would these lines be to large for just the drivers AC evaporator?
Could I then tie in an electric compressor to run when engine is not running?

Kenny
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1941 and 1945 Flxible - South Lyon, Michigan
ArtGill
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« Reply #1 on: April 25, 2010, 06:04:23 PM »

Kenny,

     I had Welch Industries recommended to me, but I haven't done mine yet.  I understand he has the spec for the evaporators for each coach and can engineer a system.  http://www.welchindustries.com/auxacsys.html.

     If you try them, post back and let us all know.

Art

 
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Art & Cheryll Gill
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« Reply #2 on: April 25, 2010, 07:55:18 PM »

I tried that link and it did not work.

WVaNative
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Handyjim
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« Reply #3 on: April 25, 2010, 08:29:12 PM »

Try this:

www.welchindustries.com/

I shortened the URL and it seems to have worked.

No dog in the fight, though!   Smiley


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JCorey
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« Reply #4 on: April 25, 2010, 10:48:00 PM »

The idea of using an electric motor to drive the compressor is a bad one. For the stock OEM OTR you need a 30 HP electric and you can imagine the current requirements and the tonnage of the motor.  It just doesn't work out from aMATH standpoint.

While your driver only set up will require much less power I think you will be wasting your time.  I thought this was way simpler than Nick has informed me.  He is the resident expert and you should tr giving him a call PM.

My advice is to get the number and mfr and "what car it came in stock and pick one up at the wrecking yard.  Might carry off the condenser while you are there.  You will need a metal fabricator t put togeher the mountfor the compressor.  I think your main problem is going to be getting the system evacuated.  Maybe a vac pump from HF.  Get the biggest dryer/filter you can connect to the thing.  Start pouring in the 134 while monitoring the gauges.  My methode is to add freon till the bubbles in the sight glass start getting wispy....it starts out being a froth after a couple cans then gets more and more clear and perfectly clear is perfectly way to much freon.  Consider how much you will spend to re run all that tubing and a few extra pints/pounds of 134 starts to look good. But Nick might tell you that the lines are too much volume and?Huh and he knows best.  Get the electric fan off of the vehicle you rape and put that in for the forced air when stopped.  Maybe two of them.  Well I think you have already spent $75 or a little less depending on the wrecking yard and the model you are chasing.  Did you notice that your compressor and condenser are "matched"..   I would mount everything and let a shop charge and evacuate it.

Good luck and send pics.

John

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« Reply #5 on: April 25, 2010, 10:54:06 PM »

If you have the compressor in the rear and the condenser in the front then you will be sending very hot fluid up the center isle floor.  I would cool that before it starts its journey.  Also, engineer in a second evap for the bedroom so when you stop it isn't cooking back there and also to serve the one that is napping while you travel.  Prevos are built like that so don't let anybody tell you it can't be done.

Thermostats....fans....duct....ooooooooh. so much fun!

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
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Gary '79 5C
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« Reply #6 on: April 26, 2010, 02:31:32 AM »

Kenny,

I would also be interested in your findings on OTR driver's A/C. I have a MCI 5C with the evap still intact.
My PO installed the froward roof A/C a little far back and it does not cut it driving into the sun.

Thanks and Good Luck,
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robertglines1
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« Reply #7 on: April 26, 2010, 05:51:28 AM »

I have a extra prevost aux air system it was mounted on rear wall of bus...is very simple set up...uses a compressor like was found on older fords the square type..also the freightliner motor I just purchased appears to be the same:the motor (60 series) just purchased for latest project was out of freight liner:The aux air conditioner has separate coil mounted on radiator. to clear post the freightlinner motor had a air conditioner compressor attached to it for cab air....
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #8 on: April 26, 2010, 06:03:48 AM »

So many units from emergency vehicles out there at good prices made by Red Dot, ProAir and others that will work for you without reinventing a unit,ProAir has one that works on 110V when parked and 12V underway I am sure there are others on the market. 



good luck
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Kenny
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« Reply #9 on: April 26, 2010, 06:44:48 AM »

To be sure all understand I'll restate what I'm thinking of doing.
Of all the OTR AC equipment, the only thing I have left in is the drivers evaporator coil, expansion valve, isolation valve and the large copper lines running the length of the bus.
My thoughts are to install a compressor from a donor car or truck and belt drive it from my 6v92.
Install a condenser in the spare tire area again from a donor vehicle including an electric fan.
Use the left over lines from the original OTR system to transfer freon to and from condenser /evaporator.
Will a donor compressor and condenser be large enough for the OTR drivers original evaporator?
Are the original OTR freon lines to large for this application or should they be replaced with smaller lines?
Is the distance from the rear of the bus to the front to far for this idea using an automotive compressor?
Yes I know I could simply buy a Redot unit but donor parts are plentiful and much cheaper.
Dumb idea or possibly feasible?
Kenny
   
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robertglines1
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« Reply #10 on: April 26, 2010, 07:03:04 AM »

I would think they would be to large for that distance .mine are reinforced refrigerant hoses about 1 inch OD about 3/8 id The set up I have had a separate compressor mounted to motor for aux air. I plan on using it on new project and am considering two units ,one front and rear with 2 separate  Ford type (automotive )compressors..as far as distance My home ac unit is mounted 30 ft away from cooling unit in furnace but it is insulated and not large id 1/2 inch maybe....need experts on this one..I'm intrested in reply also...Bob
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #11 on: April 26, 2010, 10:53:32 AM »

Will a donor compressor and condenser be large enough for the OTR drivers original evaporator?

YES!  The consideration was that you would have to choose wisely to get one that would also have the capacity to handle the rear evap.  They size the evaps by "cubic inch displacement".  A car has a 6-8 CI unit and a limo has a 10 but the Jeep uses a 10 incher curiously.  They make bigger but those get scarce and more expensive.

I heard you about using the OEM drivers area evap and ducting.  I am sure Clifford did, as well.  His comment about using a Red Dot/Pro Air pertained to putting a unit in the rear of the bus "also".  Not rethinking the front.  I would take your path for the front myself and I only remember reading a single post about replacing it.

Call an auto AC shop and tell them of your dream. Get their recommendation for a compressor and find out what vehicle(any) came with that unit.  Call a wrecking yard for the unit. 

Now, way back I suggested to Nick that the OEM condenser would male a spiffy unit for exactly the system you are describing.  I like overkill and that unit has a 8 of 10 TON capacity.  Any way...its huge.  Nick said that the OEM unit would not be properly "sized" and that my plan was not advisable.  He didn't say my system would not work but only that..... Here again, someone has been exactly where you want to go and all the questions have been thought thru and answered.  What I, and others, are sharing is what we have learned and nobody thinks that this is all that can be known.  All of us want to know what you decide and want to follow your adventure in the detail you can conveniently provide.  We all luv ya. Grin

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
mikelutestanski
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« Reply #12 on: April 26, 2010, 01:49:45 PM »

Hello:     first you should determine what you need and what you want to cool. The front glass is probably 95% of the heat gain. With my mci 7 one roof unit was not enough to do the job so I installed a split system utilizing the existing front evap and a new red dot unit installed in the kitchen cabinet.  Check with Mr Welch to see what the front unit is capable of delivering in terms of BTUs. The original may be around a ton or so but that was with R22.  The front evap in my 72 MCI 7 was  only cabable of about 9000 btus after conversion to R134. (to convert change the guts in the expansion valve)   mr Welch has the parts
  SO with that in mind I installed an 18000 btu unit in the kitchen cabinet  with a 3 speed blower for a total of about 27000 btu . You can mount the compressor on top of the blower in the rear and run it off the same pulley.
   The condensor is the problem . To get the maximum benefit you should put it on the roof.  Red dot has a unit that is available for about 700 or so.  you can find cheaper condensors if you figure out where to mount it down low.
   I bought most stuff from Welch industries . THey are nice people to deal with and they will install the whole system for you
     I would expect that you would be in the 2500 dollar range for the parts  and installation is extra.
       The bottom line is that it is possible
     
Regards and happy bussin   mike
 
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Mike Lutestanski   Dunnellon Florida
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« Reply #13 on: April 26, 2010, 02:07:16 PM »

Mike,

Great info!  Now, that "split" system has the compressor on the engine and after the condenser is there just a "Y" to the different evap units?  I was worried about trapping the oil in a loop or turned off evap or somthing.  Did you pay any attention to gravity flow of oil back to the compressor?

Thanks,

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
robertglines1
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« Reply #14 on: April 26, 2010, 04:36:10 PM »

FYI  the prevost aux air system is 2 ton..that's equal to almost 1 and2/3 of two roof units..so if I have two of these separate systems would that not equal 3 and 1/3 roof top units and cool the coach in 80 degree weather?Huh? I have these units left over from previous projects...Info came from maintenance manual...cooling with 37000 BTu now::: would that not equal 50000BTU??before I plan any farther tell me why not to use them...Tecumseh compressor HGB-1000
« Last Edit: April 27, 2010, 11:54:06 AM by robertglines1 » Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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