Mounting AC evaporator after roof raise - questions about hoses & process...

[QuixotryHugger]

Hey folks,

My bus is an '06 IC CE300 / DT466... raised the roof 12". Deleted the rear AC; kept the front AC. Had a shop drain the freon. I intend to have a shop vacuum, pressure test, and recharge the system, rather than buying specialized tools for just this project (and possibly for a mini-split, later on... though I'm open to being sold on DIY).

So now the evaporator hoses aren't long enough to re-mount to the ceiling. It's time to change that. Looking for a sanity check and some guidance.

There are 5 hoses:

1) electrical bundle - looks like there's enough extra here to reach the new height if I unwrap where it's zip-tied to the evaporator. I think they did this so the weight of the wires didn't hang on the splices; can figure out a different solution for that.
2) & 3) water drains - can extend them from the 90 degree joints (or straight joints under bus by the drain flaps) using the deleted AC hose.
4) connection between condenser and evaporator - seems like there's enough excess hose looped under the bus to reach the new height
5) super insulated hose - this is the problem child that I don't know what to do with. I assume based on the insulation over the fittings and gauge that this is for freon...

Questions:
* Does #5 need to be one complete run from the engine to the evaporator or can it be spliced? AKA can it be extended vs. replace it entirely?
* * Can I re-use the hose from the deleted AC that's been sitting for a year... or does it just make sense buy new hose, fittings, insulation (I'm assuming this is the answer)?
* * Any reason not to run the hose myself, then have a shop do the finishing work? Vs. just disconnect it... and let them clean it up.
* Does the excess looped hose for #4 serve a purpose I'm not thinking of?
* Regarding the threaded mounting brackets, they were originally riveted to the hat channels. To avoid thermal bridging, I'm assuming I want to attach these instead to wooden ceiling strapping?

Thank you!

I'll get around to creating a build thread sooner or later to share my fabrication work and tell some stories...

 

[ewo1]

Since you did a roof raise, maybe consider putting in the a/c midship and convert it to a ducted system ?

 

[QuixotryHugger]

Since you did a roof raise, maybe consider putting in the a/c midship and convert it to a ducted system ?

ewo1, it's an interesting thought... it would keep things simple to lower the AC vertically instead of raising it. Loop the excess undercarriage. Less space efficient I think, as it's shaped like the ceiling already. Midship horizontally would be more complex; it's just the drive AC so it's fine up front near the driver/passenger.

To ducting, I'll chew on that. I'll be ducting the diesel heater and minisplit anyhow so it's possible.

 

[Rucker]

I got a vacuum pump and gauges and did my own lines for the minisplit.

I also charged my automotive AC on the bus a month or two ago-seemed pretty straightforward.

IMO, not beyond the meticulous DIYer, but if I had to reconnect everything I'd do quite a bit of youtube surfing to see what I'm going to stumble in to.

Having said all that, I now have a very good mechanic to do any AC work, and I'd very likely go to him for advice, and possibly to handle it for me.

 

[cadillackid]

you sure can re-use the hose.. that looks like reduced diaater barrier hose.. similar to goodyear galaxy 4860 or such.. fittins look like an aeroquip / burgaclip stype...



the clip rings ironically are very similar to that of PEX and so is the crimp tool for them...



so you could buy new hose and re-use the fittings.. (replace the clip rings).. or you can splice more hose in with inline burgaclip or areoquip type fittings... if you left your hose wide open and didnt tape off the ends of the hoses or evaporator so they were laying open you might want to flush the system but if it stayed screwed together or taped over then you can skip this..



I would probably replace the receiver / dryer thats usually on the skirt condenser itself.. you put that part on last and then have the system VAC'd down. automotive isnt near as critical as R410 minisplit on how deep the vacuum needs to be..

 

[cadillackid]

the extra loop is likely there so the hose doesnt kink as the fitting they used was kind of wierd for where the hose needed to go so you leave a nice wide turn loop

 

[Rock-N-Ruth]

Reuse of AC hoses

Questions:
* Does #5 need to be one complete run from the engine to the evaporator or can it be spliced? AKA can it be extended vs. replace it entirely?


* * Can I re-use the hose from the deleted AC that's been sitting for a year... or does it just make sense buy new hose, fittings, insulation (I'm assuming this is the answer)?


* * Any reason not to run the hose myself, then have a shop do the finishing work? Vs. just disconnect it... and let them clean it up.


* Does the excess looped hose for #4 serve a purpose I'm not thinking of?


* Regarding the threaded mounting brackets, they were originally riveted to the hat channels. To avoid thermal bridging, I'm assuming I want to attach these instead to wooden ceiling strapping?

I am going to address something that I learned a very expensive hard way.
Any moisture contamination in your system will eventually cause a failure. What happens is the moisture mixes with the refrigerant and causes it to become ever so slightly acidic. This will eventually cause pinhole leaks in the system. It is unlikely that you capped the ends of the hose and the evaporator, condenser and compressor when you took it apart. This has allowed your components to be exposed to the elements for the time they have been apart. Now you have the ardent task of evacuating all the possible moisture from your system.



This is a two step process which begins with pressurizing your system with nitrogen or other inert gas, doing your leak test, then vacuum it down.


Then your system needs to be charged with refrigerant, brought up to operating conditions, then the refrigerant needs to be evacuated from the system through a dryer.


It would be wise to add a dryer to your system as well. If your system already has a dryer, replace it.


You can also dry the individual components by flushing them with nitrogen and then pressurizing them with nitrogen and capping them till you reinstall them. The nitrogen can stay in the system. It is inert. However you do it, you want to insure that all the moisture is out of your system.



You can forgo the drying out of your system components and you AC will work just fine, until one day it doesn't. I installed an (open box) mini split that had the caps missing on the indoor unit. It worked perfect for three years. Then it began to leak down fast. It took me quite some time to find the leaks in both the condenser and the evaporator. I was incredulous as to what caused the leaks. Until a conversation with a Carrier tech shed light on the moisture infiltration problem and what it does.


You can splice you hoses if need be, however even it you do it correctly, you introduce potential leaks, so it is better to have new hoses made.


No reason to pay someone else to run your hoses, as long as you use some sense. With that being said using wood to mount evaporators rather than the metal mounts on the hat channels is not using sense. Remember your bus is a moving vehicle with lots of stresses that occur from that motion. Bus builders , and aftermarket AC installers who do busses use that steel to hat channel consistently for good reason. It just wouldn't do for heavy AC components to fall on our children.

 

[cadillackid]

I am going to address something that I learned a very expensive hard way.
Any moisture contamination in your system will eventually cause a failure. What happens is the moisture mixes with the refrigerant and causes it to become ever so slightly acidic. This will eventually cause pinhole leaks in the system. It is unlikely that you capped the ends of the hose and the evaporator, condenser and compressor when you took it apart. This has allowed your components to be exposed to the elements for the time they have been apart. Now you have the ardent task of evacuating all the possible moisture from your system.



This is a two step process which begins with pressurizing your system with nitrogen or other inert gas, doing your leak test, then vacuum it down.


Then your system needs to be charged with refrigerant, brought up to operating conditions, then the refrigerant needs to be evacuated from the system through a dryer.


It would be wise to add a dryer to your system as well. If your system already has a dryer, replace it.


You can also dry the individual components by flushing them with nitrogen and then pressurizing them with nitrogen and capping them till you reinstall them. The nitrogen can stay in the system. It is inert. However you do it, you want to insure that all the moisture is out of your system.



You can forgo the drying out of your system components and you AC will work just fine, until one day it doesn't. I installed an (open box) mini split that had the caps missing on the indoor unit. It worked perfect for three years. Then it began to leak down fast. It took me quite some time to find the leaks in both the condenser and the evaporator. I was incredulous as to what caused the leaks. Until a conversation with a Carrier tech shed light on the moisture infiltration problem and what it does.


You can splice you hoses if need be, however even it you do it correctly, you introduce potential leaks, so it is better to have new hoses made.


No reason to pay someone else to run your hoses, as long as you use some sense. With that being said using wood to mount evaporators rather than the metal mounts on the hat channels is not using sense. Remember your bus is a moving vehicle with lots of stresses that occur from that motion. Bus builders , and aftermarket AC installers who do busses use that steel to hat channel consistently for good reason. It just wouldn't do for heavy AC components to fall on our children.

this is good stuff!!


R410A used in minisplits is much more susceptible to moisture than R134A in a vehicle... with a minisplit the Minimum acceptable vacuum is 500 Microns.. something you usually wont be able to achieve through a manifold gauge set (you use a vacuum gauge and a large hose connected to a valve directly on the system).. you also wont achieve it with a cheap vacuum pump.. you need a good one.. and it takes a while.. the reason for the deep vacuum is that in a vacuum water evaporates at much lower temperature.. at 500 microns the boiling point of water is somewhere around -10 so it boils off and is sucked out through your vacuum pump...



installing a receiver drier handles the little moisture that just cant be sucked out due to no more flow at very low vacuums...



that said at 500 microns you have likely already flowed out most all the moisture.. when you are charging your system its typically well above -10f outside so when your vacuum level reaches the point where water boils at the ambient temp it flows a good bit of moisture out as it boils off... you'll notice your vacuum dropping slower and slower as the boiling water increases pressure... by thetime you reach 500 you have boiled out so much of the moisture that you can safely charge and use the system



you likely will never achieve 500 microns on an automotive system... O-ring seals are designed to hold positive pressure very well as are the compressor shaft seals, however these arent designed to handle deep negative pressure so you may not be able to get down to much below 750-1000 microns in an automotive system... thus why even brand new bus A/C systems come with a receiver / drier on the condenser... its a known fact you will have trouble getting absolutely all the moisture out..


most definitely mount evaporators to metal... the really heavy ones mounted on the front or rear across a bus typically have through the roof bolts and unistrut on top as you cant catch enough ribs.. the side mounted units have many screws into the ribs.. 6 or 8 1/4" bolts into 2 sets of ribs..



I recently examined the wreckage of a bus that flipped in a ditch.. and while it was really smashed where it fell over, the A/C, completely bent and the plastic cover broken off, still stayed attached.. (amazingly the freon didnt leak out).. we were there to harvest the compressor brackets and condensers and the one good evaporator to re-use in somene elses bus

 

[QuixotryHugger]

Thanks for the replies and insights...

@Rock-N-Ruth - appreciate the story about the minisplit and learning from your mishap.

@cadillackid - the breakdown of components (naming fittings, more detail about my options, that extra loop) is very useful.

I see the merit of an HVAC specialist if I don't fully invest in the tools for these systems. I'm sold on single runs of hose for the freon over making splices. Sold on the receiver/dryer replacement. And capping anything that gets unattached.

I hear ya'll about mounting directly to metal and making damn-well sure the unit is secure from the forces of movement. This one I'm still thinking on though about the thermal bridging... doubled, 3/4" plywood strapping that's fastened to the hat channels... that strapping becomes structural framing. I get that steel deals with force differently than wood and is way stronger. But Loaded overhead cabinets get attached to the strapping and weigh more than the evaporator. Though they also have more points of contact than the AC evaporator mounts; perhaps reworking the anchor system for the evaporator could be another answer...

I'll update what I end up doing with the AC a bit further into the build.