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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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  #1  
Old 05-10-2017
Preacher Preacher is offline
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Join Date: Apr 2017
Location: Germantown
Posts: 159
Default Dash Air Mechanic

My '94 BMC dash air does not work and didn't work when the previous owner bought it. So it hasn't worked for at least three years. I can't pinpoint from the maintenance records when it went south OR WHY, so I have no idea where to start or how extensive the proper fix will be. So I want a guy who knows what he's doing on the BMCs. I live in central Arkansas. Anyone recommend a good A/C mechanic say...east of the Dallas, TX longitude and south of the St. Louis latitude? Basically, the SE United States? Let me hear from you.
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David Pace
Germantown, Tennessee
1994 BMC37
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  #2  
Old 05-10-2017
toolmaker toolmaker is offline
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Location: Hot Springs National Park
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David, I am tasking our dash air myself after having no luck finding a technician. The minute I say motorhome it's 'Can't help you with that '.
Even finding the correct o rings in our small town was a challenge.
Got a buddy with a vacumn pump and gages so we will see how that goes. I have posted some of my efforts.
If you find a shop anywhere around Little Rock let me know.
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Paul Cambron
Hot Springs National Park, Arkansas
1996 BMC 40
fmca 200288
eglider03@gmail.com
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  #3  
Old 05-10-2017
Preacher Preacher is offline
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Ain't nothing like a buddy to share the pain. Good luck Paul!
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David Pace
Germantown, Tennessee
1994 BMC37
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  #4  
Old 05-10-2017
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Ernest Ekberg Ernest Ekberg is offline
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Location: Weatherford, Tx
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had 4 birds- none of those worked, just run genny
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Ernie Ekberg
Prevost Liberty 45 XL
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www.ernieekbergflooring.net
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  #5  
Old 05-10-2017
Preacher Preacher is offline
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You're right Mr. Ekberg. A lot of them don't work perhaps because it's hard to find a good A/C technician it would seem.
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David Pace
Germantown, Tennessee
1994 BMC37
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  #6  
Old 05-10-2017
technomage99 technomage99 is offline
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Join Date: Sep 2009
Location: bolton
Posts: 307
Default DON'T GET BUFFALOED BY "EXPERTS"

If my 89SP is even close to the system in your coach, the overall principles are the same. Example:

I lost my A/C compressor because of an "unequal" force mounting scheme that caused a mounting ear to break off and R12 refrigerant to leak out and the compressor seized and "smoked" its drive belt. I talked to various automotive A/C places and they said that I would have to "leave the coach" while they tried to round up parts an "squeeze me into their schedule". They were talking $1500-$2000 -- hmm.

With the help of Ron my mechanic (jack of all trades) who was not mystified by auto HVAC (especially older units).
So I decided that we could fix it by just accumulating the parts and bolting them in. Here's pretty much what we had to do:
1. Buy a 2 stage hvac vacuum pump from Harbor Freight (HF) about
$110 on sale.
2. A HF gage set (~$60 on sale).
3. An air drier from Autozone ~$25 (actually a larger capacity unit which
fit in the space over the dash.
4. An A/C O-ring assortment (Autozone ~$8.00).
5. Compressor oil with the UV dye(Autozone ??$ but I recall cheap).
6. A longer freon fill hose than what came with the gage set.
7. R134A adapter fittings (Autozone Cheap).
6. 6 cans of R134a freon (Autozone ~$15ea).
7. I bought an exact model SANGEN replacement compressor from
FleetPride which was in stock (~$260). A very common unit
in trucks.
8. New belt (Fleet Pride ~ $20).

Installation:
9. Replaced air dryer.
10. Replaced compressor and added new 134A adapter fittings
onto the valve set removed from the old compressor.
11. Installed the belt and set the tension to ~60# initially.
12. Attached gage set and attached vacuum pump and let it run for a few
hours and then shut gage set valves except for low side to monitor
vacuum. Let it sit for a day and vacuum stayed ok.
13. Started the engine, turned on the A/C and did the freon fill
procedure one can at a time til total freon was approx the 4.5 pounds
recommended to replace 5.5pounds of the old (R12). The system
pretty much sucked in what it needed. High side gage was about
250# and low side was about 50# (ballpark).
14. The cab overhead vents were blowing fairly cold.

Success? Well almost.

The following spring I turned on the cab A/C and it was "luke cold".
I had Ron come over to help diagnose and the cause of the problem was apparent right away. When he took off the caps from the gage fittings on the compressor, he heard a little hiss from one of them. That meant that the Shrader valve in the valve assembly was leaking. I bought a couple of new Shrader valves and the tool to install them (they are cheap at Autozone). We ended up just tightening the original Shrader valve and making sure that the o-ring on the cap was replaced and we did the fill procedure with the gage set, hoses and a larger freon bottle with a shutoff.

Net result was the A/C blowing cold again!

Post "mortem":
If I EVER have to un-fill and refill the system again, I'd replace the expansion valve/orfice (I think I know where it might be) with one speced for R134A. I would pressure test to 200# with the air dryer replaced with an adapter in its place and let the system sit for a day or two to see if there is any pressure loss. If all was well, I'd install a new air dryer and orfice and do the vacuum and fill procedure.

The ULTIMATE (paranoid level) BEFORE doing above would be to leave on the air dryer replacement adapter. Next find and remove the expansion orfice and put the fitting its hiding under back on.
Next, remove the hoses from the back of the compressor and force "HVAC system cleaner" into the high side hose and LET it drain it out the low side hose into a bucket onto a white rag to see how much crud comes out. You might need to use a lot of cleaner and want to do it both directions to dislodge stuff that is stubborn. Then blow out the system with "shop air". The cleaner evaporates pretty fast. Next, connect compressor, install expansion orfice, dryer and tighten all fittings. Reassemble and do the vacuum and fill procedure (above).
All the above takes some time, but doesn't cost much beyond vacuum pump and a gage set.

I ended up using all my "new tools" and accumulated knowledge to fix the A/C on two other cars. I am not sure I'd do this with "modern" cars. They seem to design stuff to force you into the dealer.
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Cal -- TECHNOMAGE99
1989 SP36
Bolton, Ct.
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  #7  
Old 05-10-2017
technomage99 technomage99 is offline
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Location: bolton
Posts: 307
Default Oops forgot something -- compressor oil

I Forgot to mention in my previous post that Ron and I added compressor oil
(whatever amount SANGEN speced) before bolting on the rear fitting and valve assemblies and installing.
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Cal -- TECHNOMAGE99
1989 SP36
Bolton, Ct.
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  #8  
Old 05-11-2017
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overthehump overthehump is offline
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Location: Lovington
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Thanks for the write up. I'm going to have to do this to my 94 BMC as the dash air works but doesn't cool. Thanks again.
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Ron & Patsi Humphrey
Lovington, NM
1994 BMC 37'
2010 Jeep Wrangler Mountain
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  #9  
Old 05-11-2017
markkitch markkitch is offline
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Location: Athens
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Thanks Cal, you have given me the confidence to tackle this on my own!
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mark kitchens
Athens, Tx
1995 WB42
C: 214 477 3757
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  #10  
Old 05-11-2017
Preacher Preacher is offline
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I'll add my thanks Cal. A thorough explanation.
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David Pace
Germantown, Tennessee
1994 BMC37
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