r12 to 134 conversion

[muldoonman]

Just purchased 1991 converted prevost sitting for years. The AC no workie on engine or house AC. Can't get it worked on in Odessa Tx.  It has the central ac system (prevost) that came with bus. I called Prevost Service Center in Ft Worth (400 miles east of where the bus is) and They said they do the switch on bus ac. . Has anybody done this and how does it cool afterward. O yeah guys. The money has already started rolling out of my pocket.

[robertglines1]

It is standard practice- was already done on the 89 when i got it. Any place can do it .These systems are not specialized to just prevost. especially when 400 miles is involved.. Ck to see if it hasn't already been done.Should be a sticker if it has; usually on Air Cleaner visible through rear door. Does drivers air work?  Actually you need to have a Ac guy look at it .That person could have just general knowledge and be of help. A Charter service Shop in your area could help diagnose /fix

[stevet903]

I did this on my 89 with drivers air.  Prevost will want a ton of money, since they will want to switch all the hoses barrier hose to do the conversion.  I thought this was BS, so I just filled mine up with R134.  It worked great for a while, until the 21 year old hoses began to split.  Some in the engine compartment were so hard and brittle that a slight bend would break them in half.   My advise is to replace the hoses, but there is a cheaper way.  You'll find on the drivers air (small compressor) system that they use Aeroquip hoses and reuseable fittings.  Keep the fittings and replace the hose with FC802 hose.  I got mine here:

http://www.aeroquip.cc/fc802-06refrigerantandachosefc802-6.aspx

It's a pain, especially getting to the front hoses, but mine has been working great for a couple of years.  Be aware that Prevost made up some unusual, non standard connections, so try to reuse the ones you have, or you'll end up brazing on pieces from several connectors to make the ones you need.  Flush the system with an A/C solvent to get some of the old oil out, replace the drier, and replace the expansion valve with an R-134 one while the system open.  Replace the oil with an R134 compatible oil (it will take more since there are 40' of lines each way) evacuate and charge.  I'm sure the process would be the same on the central air.

[muldoonman]

It's still r12. I was just thinking it would be better at Prevost center. The service Manager said they would replace  lines, fittings and seals. He said it would be down 2 or 3 days. I went to a couple local ac places and one said no and the other was out about 3 weeks. This bus has been sitting for years in a barn. I have all Prevost manuels but nothing on conversion operations. I can't get nothing to work . I'm bus dumb. I have lined up a place North of San Antonio to go through and check all systems.(Kieth Whitaker RV)

[muldoonman]

Oh, this has  the central AC system.

[robertglines1]

Decision time: open a can of worms here        fix or not       $3,000 up to $5,000  plus (get quote) plus maintenance.  or run gen set and house air plus driver air going down road.  I do the latter.  buy allot of fuel for gen set--for repair cost of bus ac. For no more that I use going down the road.  If you just need freon in system add freeze 12 and run system till it craps out alltogether.--See search     Direct replacement for R-12 freon   . by the way 27lb freon   Bob

[Boomer]

I agree with the above.  Gonna take a lot of money to restore a bus air system that has been sitting dormant in a hot climate for all those years.  Unless it's going to be driven a huge amount in hot weather, not worth the money IMHO.  Put it in the house A/C and generator fuel.  Besides what is mentioned above you will wind up replacing the compressor crankshaft seal also, maybe hi-lo switches, on and on.  Very spendy unless you can do it yourself.

[muldoonman]

Thanks Folks.
Glen S.

[papatony]

the advice to use freeze 12 is a very good thing I have used it for years and have had no problems. it is a good replacement for r-12 and cheaper than 134.

[niles500]

I'll third the idea of topping it off with freeze 12 - if that doesn't work long term then you can consider other options - What type of house system(s) do you have?

[muldoonman]

Niles, 3 Cruiseairs in front under driver area. They say any ac guy can charge these (r22 freon) but so far the ones I've talked to runs away fast. One in West Texas said he didn't work on Buses or Space Shuttles. Now that's funny right there.

[JohnEd]

I have not a clue as to why your hoses would NOT need replacing.....BUT....so far they aren't proven to need it.  Would be  a stroke of luck if all you needed was a charge of Freeze 12.  I would suggest that you get her to a ac shop and put a light charge of Freeze in and then meticulously go over the entire system with a "freon sniffer" and PROVE that your seals, etc. are bad and need service.

You can rebuild the hoses, as was mentioned, for a fraction of the cost of having Pre do it.  Rebuild the compressor seals by removing the compressor and taking it to a shop and you will save a ton.  Hire a local helper with good references to R&R the major components and pull hose.  Shop for labor and materials and tools.  You need a pro for the sniffer work and don't let him stop when he finds the "first" leak or you will go broke recharging the system.

My hoses are 1973 vintage and still hold freon for a year.  They have behaved this way since 1990 and I think the compressor seals are the culprit but the freon is cheaper than a rebuild.

Good luck and let us know how it all works out.

John

[luvrbus]

I'll make a suggestion to you it would be best if drove the coach over to Texas Custom Coach in Pipe Creek and let them walk you through it I think Cole was the one that started Texas Custom Coach or the other converter in that area.
If you are going to keep the factory air take it to Prevost in Ft Worth it will be done right and you will have a warranty you can soak big bucks in that system besides what someone charges you if not done right JMO.
The Cruiseair are a marine unit and they are touchy and RV dealers will just ripped your a** and know nothing fwiw those 3 units were over 7000 bucks in 1991 I know that for a fact I had 3 in my bus.
A RV dealer is not the place to take a bus conversion been there done that they have no idea on how a bus is built I don't care what they tell you

good luck

[Hi yo silver]

ThermoKing! When I bought my MCI three years ago, the original over-the-road a/c didn't cool. After kicking it around for a while, I wound up taking it to Thermoking.  They pulled a vacuum on the system to check for leaks then charged it with Freeze 12. I even bought an extra cylinder of the stuff. (Gotta get it through someone with a card.) About 2 1/2 years later, it's still cooling well on that original charge of Freeze 12, so I'm a fan of the stuff and of ThermoKing. Worked for me. Good luck. Oh, and they have a website where you can check for a local shop. They are the guys who maintain a lot of reefer units in over the road trailers. Let us know what works for you.
Dennis

[Hi yo silver]

Forgot to tell you, I spent less than $500, not counting the extra cylinder.
Dennis