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BMC (Bluebird Motor Coach Unique Issues) If you have a unique issue with your BMC coach and it can't be answered in one of the other forums here, then this is where you can list it.....List your BMC Parts here too.

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  #11  
Old 05-18-2009
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bwinter1946 bwinter1946 is offline
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OK, Here are my most recent numbers for my dash A/C R-134 system:

Engine run at 1100 RPM. All windows and door open. A/C on MAX and highest fan speed selected. Motorhome in direct sunlight. Discharge temp measured at the high center vent in front of passenger.

Ambient temperature measured in front of condenser: 100 degrees
Discharge air temp: 50 degrees
Hi Pressure side: 195
Low Pressure side: 25

All things considered, it seems fine to me. (50 degree drop)
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1997, 37' BMC
1999, Jeep Cherokee, Toad
1970, VW Baja Bug, Alternate Toad
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  #12  
Old 05-18-2009
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rwoody rwoody is offline
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i would dump a little more in......you can see 275 with no problems

i like 37 degree air but you are fine with 50 degree drop
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  #13  
Old 05-19-2009
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bwinter1946 bwinter1946 is offline
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You may be right Woody. However, I have not had much luck getting a R-134 system to 37 degrees. The best I have been able to get has been 40 degrees with 40-50 degrees fairly common with an outside temp of 100 degrees.

Now with an R-12 system I used to get those down to 35 - 40 degrees. They could freeze you out, but sadly R-12 is a thing of the past.

Just a rank amatuer here.
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1999, Jeep Cherokee, Toad
1970, VW Baja Bug, Alternate Toad
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  #14  
Old 06-22-2009
odbwedge odbwedge is offline
odb bill
 
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Default a/c question

i have a bb 1984 fc has anyone have info, on how many pounds of 134 it takes for the driver unit not the roof units thanks
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  #15  
Old 06-22-2009
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bwinter1946 bwinter1946 is offline
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Unless modified the 1984 Dash Air Conditioning system you have originally came with R-12 not R-134a.

Has yours been switched over to R-134a?
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Madera, California
1997, 37' BMC
1999, Jeep Cherokee, Toad
1970, VW Baja Bug, Alternate Toad
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  #16  
Old 06-22-2009
odbwedge odbwedge is offline
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that's the same thing i;m wanting to know on my 84 what;s the high side and how much 134?
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  #17  
Old 06-22-2009
odbwedge odbwedge is offline
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yes i changed it over
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  #18  
Old 06-23-2009
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I think the general rule of thumb is you charge R-134 to 80-85% of what it used to hold with R-12. However that said, if your discharge air temp stops dropping or rises then the system is fully charged.

Also please note, I am a rank amatuer and this advice is worth what you paid for it. Professional advice is recommended.
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1999, Jeep Cherokee, Toad
1970, VW Baja Bug, Alternate Toad
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  #19  
Old 06-23-2009
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Has anyone tried DURACOOL® Refrigerants? They are natural hydrocarbons that deliver similar pressures, temperatures as their traditional counterparts R-12, R-22, and R-502.

http://www.deepfreezeinc.ca/dref.htm

This is from a GMC Motorhome site:

Conversion to Duracool
Duracool is a packaged propane butane mix that cools with greater efficiency than R12, and cost about $20 to fill your GMC. It is illegal in some states. I am testing it in my GMC, which ran my own "home brew" of propane and isobutane (55 to 45%) that worked better than R12 but was a pain to refill. Also my Head pressures were a little high (250 psi on a hot day). Now I'm running 40 to 140 low to high. If you don't know what I'm talking about that's ok. Here's what's important.
My system leaks. I don't want to fix it as the leak is very slow and when I redo the whole coach I'll replace everything. Until then what can I do? I ran my own mix, but I wanted to try a commercial hydrocarbon mix. Duracool seams to work much better than R134a, and possibly better than R12. I won't know until further testing. But, this stuff is cheap, $5.50 for 6 oz, which equals 15 ozs of R12. That means about $20 to fill your GMC.Mark A

Here are some bits of information that we learned at Osoyoos: (5/5/5)
1 AC technicians do not like to use 134, it is harmful to their health.
2 You do not need a vacuum pump to charge with Hydrocarbon refrigerants like DuraCool (Propane).
3 In fact they work better if you do not pull a vacuum.
4 Propane will mix with whatever you have in your system. There’s nothing to change.
5 Recover the existing refrigerant (most of our systems are already empty).
6 Add 3 cans of DuraCool
7 Use Glacier Gold if you have a leak, every can has a dye for leak detection.
8 Run the compressor, and measure the low side with your tire gauge.
9 You should have 30 lb of pressure. If it’s too high let some out, a little low will be ok.
10 Put on the 134 adapter connections, and the system is legal.
11 Mark the system as filled with DuraCool or Propane.
12 You are done, no gages, no pump, no changes.
13 Propane is more efficient. Your compressor will use 40% less horsepower.
14 The head pressure is lower with Propane, the compressor will last longer.
15 It will cost you $30 for the Propane and taper hose.
16 Propane has a higher auto ignition temperature than 134. (Propane still lights more easily)
17 Propane leaks less than R12.
It has never been easier to do your own AC work. It is interesting to note that there is also a hydrocarbon mixture that works on a home or coach AC to replace the R-22 with the more efficient refrigerant.
Note: The EPA has issues with Hydrocarbon refrigerants. You should read this link and make your own decision: http://www.epa.gov/ozone/snap/refrigerants/hc-12a.html#q9
The above information and more technical detail are available on these web pages:

http://www.foxtoolsupply.com/
http://glacier-gold-refrigerants.com/index.html
http://hc12ausa.com/
http://www.duracoolusa.com/
http://www.duracool.com/
http://www.duracool.com/ecom/shoppingcart.html


DURACOOL FAQ LINK
WEST COAST SOURCE FOR DURA COOL
I bought a case of 12 cans and several of the fittings from them last year. I was just over there a couple of days ago, and they still carry it. Prices are competitive.

FRUIT GROWERS SUPPLY
3631 CENTER ST
RIVERSIDE, CA 92501-1126
Phone: 951-369-9741 Tmaki

Called Chet at Shamrock Consultants in Fresno Ca.
Shamrock is the out let for Duracool 12a in California or as Ken would say Kalifornia.
His phone number 559 255 9413

IDEAL COOLANT SOLUTIONS Serving Washington and Oregon
WEBSITE http://www.idealcoolantsolutions.com
Craig Piguet - Oregon Sales
12530 SE Oatfield Rd. #2
Milwaukie, OR 97222
Email cpiguet@idealcoolantsolutions.com
Telephone 503-419-6392

Peter Strait - Washington Sales
Prairie Rose Lane
Lyle, WA 9863526
Email pstrait@idealcoolantsolutions.com
Telephone 360-518-4142
http://www.deepfreezeinc.ca/distus.htm#Anchor-42912

TM
Flammability OF HC refrigerants

Flammability is not much of an issue compared to the use of gasoline in your engine compartment.


For a number of years now there have been many messages posted on the GMCnet about the use of hydrocarbon refrigerants to replace R-12 or R-134a. Products such as Duracool and HC-12a, which are both mixtures of Propane and Iso-butane, are currently being used by many GMCers.

I felt it might be good to examine the reported track record of hydrocarbon refrigerants.


Major conversion of car air conditioners from fluorocarbon to hydrocarbon refrigerant commenced in the USA in Idaho during 1992. I have been looking on the Internet for statistics and find that today over 10 million car air conditioners worldwide have been converted, about half of these in North America, and over 30 million user years have accumulated. Almost all of these have been drop-in conversions usually costing less than US$50. Indonesia, Korea, Philippines, China, Canada, Australia, Japan and other countries also have many systems with drop-in HC charges. In spite of this, there have been no reported fires, explosions or injuries to occupants caused by the flammability of hydrocarbon refrigerant in car air conditioners. Many cars with hydrocarbon refrigerant have had frontal collisions which punctured the condenser. Arthur D. Little, the well known consulting firm, estimated the frequency of the refrigerant catching fire from this common accident as once in ten thousand user years, so over 3,000 such fires should have occurred worldwide; if this had happened it would have been big news and widely reported. But even so, no such fires have been reported. There are reports of such accidents with the refrigerant not catching fire. HC refrigerants have a condenser pressure 10% lower than HFC-134a, making catastrophic leaks many times less frequent. HC REFRIGERANT IS ONLY FLAMMABLE BETWEEN 2 AND 10% VOLUME


CONCENTRATION IN AIR. It is non-flammable inside the refrigerant circuit where the concentration is always above 10%. HC refrigerants have a high leak and low flame velocity so an ignited leak tends to blow itself out. HC refrigerants have a lower density so the charged mass is only one fourth of HFC 134a. When this small charge leaks from the evaporator into the passenger cabin, air leaks keep it non-flammable by preventing the concentration from
exceeding 2%. HC refrigerants also have an odorant added to help prevent accidents.

Has any of the GMCnetters actually seen or even heard of an actual fire?

I feel it is a matter of personal choice as to one's aversion to risk. 1 in 50 million might be acceptable odds to some but might be unacceptable to others. I personally feel that 0.00000002 is sufficiently close to zero. So, the benefits of using HC refrigeration in my GMC far outweigh any fire risk in my mind. You
have to make up your own mind on this, though.

Europe is currently undergoing a transition away from the use of R-134a due to its potential of adding to global warming. Many European countries signed the Kyoto Protocol (the USA did not). Replacements under consideration are hydrocarbon products for existing systems and a newly designed system using CO2 as the refrigerant. However, existing systems cannot use CO2. It will require a different heat exchanger and re-engineering of every component. The CO2 systems will have pressures in the range of 1500 psi to 2000 psi or more. This is about 10 times the pressure found in a conventional AC system. Mercedes has indicated that they may have a CO2 system by 2005.

The advantage of using hydrocarbons instead of HFC-134a is that the greenhouse effect of refrigerant leaks could be eliminated completely. The only argument against HC blend refrigerants, the flammability issue, has proven to be a non-argument. Plus, the international community, as well as Greenpeace and the UN, are advocating the use of HC blend refrigerants in all applications. This in response to the Kyoto agreement which scheduled the phase-out of greenhouse gases as
the Montreal Protocol scheduled the phase-out of ozone-depleting chemicals. >>>>>

I am not taking a political stand on these issues, I am just reporting information that I have reviewed. Emery Stora (5/28/06)




Comparison of refrigerants

AUTOFROST
R406A (Tradename Autofrost) does everything > you claim for Duracool, but IS legal. Once again, why fool with an inferior, illegal product like Duracool, when there are far better alternatives?

R406A is not a Hydrocarbon refrigerants, and is basically nonflammable. Good stuff there, if you are worried about flammability then R406A is a good refrigerant to use.
Now here are a few problems with R406A:
First, this product requires barrier hoses, so ALL AC hoses must be replaced. Duracool can use the old original hoses.
R406A can have compatibility problems with the compressor seal. Your compressor seal must be Neoprene, or it will fail, Duracool has no compatibility problems.

R406A must be recovered, ie; must be sucked out of your system by a licensed AC repair shop, (good luck, the vast majority of AC shops won't dare contaminate their equipment with it, you have to find a shop pushing R406A). You can dump it in the atmosphere but that's illegal, and

R406A is only 95% non-corrosive to the Ozone layer, Duracool is 100%, and though they tell you to recover it, the backyard amateur owner mechanic can dump it, it has NO regulated HCFC's.
R406A cannot be used with ester (PAO) or PAG oils, if you system has been converted to R134 then it almost certainly contains ester oils and must be flushed, especially the compressor.
R406A contains some very small molecules, and if there are any leaks in your system, they will allow the "lighter" elements of R406A to dissapear,(why it needs barrier hoses) and your system will become inefficient and ultimatily lose cooling ability.
Other than that, R406A will work great, and if you rebuild your system and cover these problems it is an excellent, fire safe refrigerant. I use duracool because I'm cheap and it's cheap and will work great in an old leaky system. It costs be about $30 to charge my system, and so far 2 years down the road it's still working great.

In all my years of working as an auto mechanic, I've not seen a car with the peculiar state of damage that would allow the evaporator to leak without massive leakage under the hood. Remember, the amount we are talking here is ounces, there is very little of this stuff in the AC system. I carry a gallon of camping fuel in the coach for our camp stove, that is far more dangerous that my AC. And yes, that needs to be stored outside. One last thing, go to the Duracool website and read up on the legalisms, you might be surprised. I understand that some insist on this, and others insist on that. I insist on nothing, except tolerance for other viewpoints.
Thanks;
Mark A

SECOND KNOWN GMC - DURACOOL INSTALLATION
After pumping the system down and making sure that this time there were no leaks, I took the plunge. The directions say that you fill the system by volume and not by amount. That means you need gages to monitor the low side while adding the DuraCool and then you are suppose to bring the pressure up to 35lbs. This is when they say it is full.
There was a chart at duracool.com that shows the equivalences between DuraCool and R12. This shows 6 oz of DuraCool equals 17 oz of R12. Our systems use roughly 3.5 lb. of R12, so this converted to just a little over 3 cans of DuraCool. The kit that I bought from DuraCool had 3 6 oz cans in them. I went ahead and put 2 cans in quickly, and the pressure came up to around 10lbs. I then slowly added the 3rd can, and watched the pressure come up to the 35lbs.
I let the system run for 30 minutes or so (at about 1000 rpm), and the pressure stayed at the 35lbs. So, I didn't add anymore. It's blowing real cool, and we are excited about having AC for the trip this weekend. All in all I'm happy with it. Now I need to make the recirc mod, cause right now all of the inlet air is coming from the hot engine compartment.
The DuraCool kit cost me $37 (3 6 oz cans plus the hose to puncture the can and attach it to the R12 shrader valve). 5 12 oz cans of R12 would have cost me $100-$150, and that would be if I could get anyone to sell it to me.

Conversion To R134a
R134a does not require barrier hoses, only refrigerants containing HCFC 22. The original oil used in R12 systems is not soluble in R134a so a different oil must be used. If Ester Oil is used, no special "O" rings are needed, and the system does not have to be flushed.
The receiver dryer should be replaced to provide adequate water absorption, and because it is often impossible to drain the old oil from it. The compressor's oil should be drained. The expansion tube (if any) should be cleaned or replaced. Only most of the old oil needs to be removed, the oil R12 oil is soluble in the Ester oil, but you don't want too much of it. Replace the receiver dryer and drain the compressor and you should be ok.
Vacuum it down and check for leaks. I used to do this by injecting about 2 ounces of R12 (in the old
days, the 1970's) and then charging the system with 90psi of Nitrogen. Any leaks would be easy to find.
When the system is to your liking re-vacuum it down. In most GM systems add 6 to 8 ounces of Ester oil and charge the system with R134a. You're done for about 5 to 8 years.
The calculated amount of R134a for the stock GMC according to my AC guy is 2.9lbs.Henry
I was NIASE approved as a general mechanic, with several specialties, one of which was AC systems. The name NIASE will tell you how long ago this was, I believe it is now called ASME. Everyone has different needs. R 406A is a fine product, has a low compressor high pressure, and is cold. If you replace your hoses you shouldn't have any problems but for your shaft seal, and that can be rebuilt. I don't know of any shops that maintain a recovery unit for this product but I live in the boondocks, in a large town or small city I bet someone has one. You will need it because the R22 part will leak down unless you have a very tight system. That is why I prefer R134A, which does NOT cool as well, but can be filled up at home anytime. Good for old leaky cars, but I as a professional cannot service any system that leaks without repairing the leak, EPA regs. If I find a small leak at your shaft seal (almost always) I am forced by EPA regs to replace the seal or pump. Pain in the butt and big unnesessesary $.
One last thing, I know of several shops that convert to R134A by recovering all the R12, adding 4-6 ounces of Ester oil, and charging with R134A. No other changes. I don't have the balls for that but they say it works and works for years. They just don't admit that this is what they do because this is a real profit center for them.
Mark A
Wind Wings and Screens
I have made the following colored wings:
Solid - Black, White, Light Blue, Dark Blue, Brown
See thru - Light Green, Gray, Smoked copper, Blue.
But I could get other colors. All the hardware to install the wings are made of stainless steel.
Of course if you have wings you must have screens. The screens I make have an aluminum frame and
fiberglass screen mess and are self contained.
If you are interested, you can reach me by
e-mail dsekula@tds.net
or phone (765) 522-3241
By the way, I am on the digest. I am usually several days behind in reading the posts.
Blaine Merrell
101 Way West Airpark
Bainbridge IN 46105
Climate Control Fan Switch "off" Modification
Fresh Air Vents
Air Conditioning Upgrades
Major change occurred in two year increments, with the best being the '77/'78 coaches. After our recommended maintenance/up-grades we were happy with the Dash A/C operation. Sealing the doors to separate the Hot from the Cold is a small job with big pay back. Also, converting the A/C into a completely air recirculation system was the biggest pay back. A simple 10 minute job for all systems except for the coaches that have the added "Air Horn" to the center/bottom dash. This system is called the "Type II" system & requires more work to achieve some Air recirculation...a half-day job, but worth it.
With my Privacy Drape closed behind the Pilot/Co-Pilot seats, recirculate mode, outside air at 100 degrees, I am able to obtain 38 degree air out of my center a/c duct. After a while, it gets too cold & we open slightly the drapes to get the desired cooling. Needless to say, we are now happy w/our a/c system. The Dash A/C can not cool the entire coach on a Hot Day (above 100 degrees), but does a great job of cooling the cockpit area.
In some cases, only adjustment of the Temperature Door for full closure makes a significant difference in cooling. Shutting off the Hot Water from flowing thru the Heater while in the A/C mode is also very helpful. The adjustment is located behind the Control Panel as an in-cable adjustment. Adjust for full Temperature Door closure as observed out front, drive side of A/C & Heater Box.Duane
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Covina, CA
1983 FC33 - Thunderbird
Blue Bird Maps 156

Last edited by Green_Bird; 06-23-2009 at 04:06 PM. Reason: Added info
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  #20  
Old 06-23-2009
Frank W. Frank W. is offline
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Join Date: Jan 2008
Location: Woodbridge, VA.
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Smile 134a for FC

Quote:
Originally Posted by odbwedge View Post
i have a bb 1984 fc has anyone have info, on how many pounds of 134 it takes for the driver unit not the roof units thanks
I redid my FC dash AC about 4 years ago (new York compressor, dryer, Red-Dot roof condenser, flush, vac and recharge) and this summers prep showed the AC to be very weak as to cooling.

So today I replaced the dryer/filter (precautionary), put a vacuum on the system and then recharged. At 3 1/2 cans of 134a (12oz cans) I am getting 25-30# Low and 195-200# High. Our temp now is 85 and with a meat thermometer I read 62 at the vents at 1000 rpm sitting in driveway.

These numbers are offered just as a reference point to get you in the ballpark. I recommend you buy a gauge set.

Be aware that I do not have training in this area...just self taught/ignorant and somewhat lucky most of the time.
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85FC33
Woodbridge, VA.

Coach photos & comments: http://www.wanderlodgeownersgroup.co...php?albumid=79

Last edited by Frank W.; 06-23-2009 at 04:37 PM. Reason: added rpm info.
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