Time for new AC units? Let's talk options

andyps · August 21, 2015, 04:23:45 PM

Hi everyone! My bus (1964 4106) has two split units from the late 80's. They are Duo-Therm Model 56915-001 units. I have two. They are splits. The unit for the back of the bus works, but probably needs more refrigerant (it's cold, but could be colder, and it's frozen over a few times). The unit in the front is the problem unit. It doesn't blow cold. When I turn it on and the compressor finally kicks on, it blows cold briefly and then just warm. The compressor in the condenser unit under the bus definitely kicks on, but the fan never does. I thought it might be the capacitor, so I pulled that and tested it. It tested a-okay, but I replaced it anyways. The fan still doesn't kick on. So maybe fan motor?

Since they are pretty old, I am wondering if I should just replace them both. They are 13,500 BTU each and if they were working at 100% I'm not sure they would be enough to cool the bus. Right now I have been running the rear unit and I have a 10,000 BTU portable up front. If I turn both on at 5 or 6am I can get the bus down to 70 by 8 or 9am, but as soon as the temp outside is at a 100, it's a losing battle. They can't keep up.

We need the bus to have sufficient, reliable AC for not just going down the road, but for running in our backyard (where the bus is).

I've searched these boards (and others) relentlessly for the past few weeks and read hundreds of threads and I have come up with two options:

Option #1: Mini split units. Probably one 24k/30k/36k dual zone unit with the recessed ducted evaps. This would be a direct replacement for my current system, utilizing my ducts I already have. Then I might want a second 12k unit with a wall mount evap/blower to go above driver at front of bus. The recessed ducted units would fit where my current ones do, use the current ducting and utilize the same hold to run all the lines. Downside to this is it's the more expensive option by a lot.

Option #2: Window units. I have read a lot about converting these to central air more or less. I'd get 2/3 big boy units and mount them in the bay and then run all the ducting from there (cold air inlet/outlet, hot air inlet/outlet). I'd run the control panel up to the bus as well. I have seen some people do this with a lot of success, but I realize this is a lot more work and will take up more bay room. I'm not scared of the DIY, but I wonder if it's worth the $$$ savings. Alternatively, I could mount them in the bus where my evaporators are currently, and build an insulated box with ducting (and probably duct fans) for the hot side.

Either option I'll need 220v. My main bus hookup is 50amp 220v. My current units have a 30amp 110v breaker each. I can remove those and replace with two 15amp 220vs for the new units (correct?). Any other issues with going 220v?

So any thoughts? Any options I missed? One caveat. No roof airs. Don't like the look. Don't like the noise. Don't want to the cut holes (plus I already have ducts in place).

Here are some reference photos:

Front half of bus vents (over kitchen)

Evaporator/air intake:

Thermostat:

Condensers in bay:

Portable unit

Jon · August 22, 2015, 05:01:26 AM

I'd bet given the life of the units they are well constructed and repairable. I have CruiseAirs on my bus and they are serviceable. I'd surmise there are replacement parts available at places like WWW Grainger and other supply houses.

The fact the compressors are running suggests recharging or even the replacement of components like capacitors or condenser fans plus cleaning the condenser coils might get them working again. Even if the cost matches the alternatives it maintains a quality appearance to your A/C system.

robertglines1 · August 22, 2015, 05:34:56 AM

I did the window ac system. It worked but not great and took up a lot of space. If you do splits go for separate 120 V units--if you loose one your not down like multiplex system. Your present units can be fixed for most part. Dirty condenser or evap are biggest reasons for failure. Nick Badame (one of the moderators is the GRU-Gru on your system. Your location would help us help you. Bob

belfert · August 22, 2015, 07:36:13 AM

Have you contacted Dometic to see if they still have parts. It looks like Colaw RV Salvage has a used one they say is tested and guaranteed. No idea on price.

eagle19952 · August 22, 2015, 10:36:49 AM

like an engine coolant radiator, evaporators must have a useful life expectancy. just curious if anyone has a guess as to how long one is worth keeping alive, the A coil that is ?

I replaced my 25 year old A coil only because the catch pan rotted out and it had to be removed to replace the condensate pan.

How much longer will R-22 parts be around ?

And last I have heard rumors that at a certain SEER rating parts and service will be no longer available.... any truth to that ?

luvrbus · August 22, 2015, 10:44:49 AM

That is such a neat and clean install no way would I ever give it up either

andyps · August 22, 2015, 01:43:14 PM

Quote from: robertglines1 on August 22, 2015, 05:34:56 AM
I did the window ac system. It worked but not great and took up a lot of space. If you do splits go for separate 120 V units--if you loose one your not down like multiplex system. Your present units can be fixed for most part. Dirty condenser or evap are biggest reasons for failure. Nick Badame (one of the moderators is the GRU-Gru on your system. Your location would help us help you. Bob

Hey Bob, good info. Yours was one of the installs I looked at (thanks for posting photos that were easy to find on the boards).

For the mini splits, I was still thinking of going with separate units. One would be a dual zone to replace the current system. Then I would add a second system with a wall mount for the front of the bus (for redundancy and additional road cooling).

With the 120v units I'm limited to 12,000 BTUs and with 2 of those I'm not sure it's enough. Thoughts?

Quote from: belfert on August 22, 2015, 07:36:13 AM
Have you contacted Dometic to see if they still have parts. It looks like Colaw RV Salvage has a used one they say is tested and guaranteed. No idea on price.

I have been in communication with Dometic. They call it obsolete and have no leads on parts. They were nice enough to provide manuals and parts lists, but that's as much help as they can be.

Thanks for the Colaw RV Salvage lead. I could go that route, but if something happens again I'm in trouble. We plan on using the RV for friends/family/guests while it's in the backyard. If the AC goes out on a Texas summer day, there's not way to get it fixed in a reasonable amount of time. This is one of my biggest reasons for wanting to get modern units.

andyps · August 22, 2015, 01:44:55 PM

Quote from: luvrbus on August 22, 2015, 10:44:49 AM
That is such a neat and clean install no way would I ever give it up either

Yes the install is very nice, so I'd like to maintain that. That's why the recessed ducted evaporators were attractive to me.

andyps · August 22, 2015, 01:48:43 PM

Hey everyone, after seeing replies, I realized I should be more clear about one thing. I really need a reliable, powerful system. The system will be used very regularly. If I were to maintain my current system I'm worried I'll be stuck in the situation again very soon while we have guests in our bus.

I've called probably 30 or more AC repairman in my area and no one wants to come out and look at these. I've had luck with 2-3 RV-specific repair companies, but all of them have weeks of wait time and they already told me they cannot get parts. So they'd either have to find other parts that work, or replace the units.

My thinking is that by going mini split or window air I'd have much greater choices for repair no matter where we find ourselves vs. my 1085 units. Thoughts?

TomC · August 23, 2015, 07:56:44 AM

Those units look very much like Cruise Airs-the same units that to this day are being installed on most every boat. The only difference between your system and boat systems is that you have air cooled condenser/compressors. I would get a good A/C man over to look them over. Considering that you'd spend towards $2,000 to get two roof tops installed, that would be a lot of repair.

When I got my two Penguins from Nick, one of them had no Freon. I had an A/C guy come by and he charged it. Worked for a while, but then was obvious it had a leak. We finally found a pin hole leak on one of the Freon line bends. He soldered it and installed a charge fitting. It has been fine now for years. Good Luck, TomC

TomC · August 23, 2015, 08:03:16 AM

In the meantime, buy two portable room A/C's with at least 12,000btu apiece. Here's the catch-make sure you get ones with two hoses each. One pulls in air, the other pushes the hot air out. With single hose units, you always have to leave a window open since it is constantly pulling air in and pushing it out of the bus. You can't possibly get the bus cool enough this way. I have three of the dual hose A/C's in my condo. With all three running, they get the job done quite nicely. They will be about $500 each. Good Luck, TomC

Darkspeed · August 23, 2015, 08:35:43 AM

I will be doing my 4106 air project soon and my current favorite is > http://www.fujitsugeneral.com/PDF_06/9-12-15RLS3%20Sell%20Sheet.pdf because of the high efficiency.

How well insulated is your 4106? If you have the OEM single pane windows and the OEM insulation you may need a pair of the 15K BTU units.

The high efficiency units are about $1700 > https://www.theacoutlet.com/15RLS3-ASU15RLS3-AOU15RLS3-15000-Btu-25.3-Seer-Fujitsu-Single-Zone-Mini-Split-Heat-Pump-System.htm

You can get a lot less efficient units for a lot less money.

robertglines1 · August 23, 2015, 09:21:25 AM

Had the efficiency discussion before. Basically the roof tops don't even offer a factor. Common consensuses if they would + 9seer. I have used 15 and over in my base criteria also must be inverter technology. The ones in my home are 15 seer and cut my electric bill over 50% comparing past years. Everyone does this different .Have thought about putting one under cabinet. i know it is not preferred place but seems the cruise air evaporators work there? Just for discussion... Bob

Darkspeed · August 23, 2015, 09:31:17 AM

Also the roof units are rated at max BTU where split systems are rated at nominal BTU.

For example a 15k BTU nominal split system might be 18k BTU max cooling.

luvrbus · August 23, 2015, 09:38:52 AM

This deal is never going anywhere till someone that stays away from power poles,RV parks and use their bus for 20,000 miles a year. The ones I know that use their bus the most have the most trouble it seems like to me

No body ever tells if they have problems or not the few I know with mini splits it's about a 50/50 toss up.This is not uncharted waters with the mini split Ace had those in his Eagle 12 or 15 years ago, he sold his Eagle then he used roof tops on his H-40 maybe just for space I don't know