Built-in Ambulance Heater/AC question and mod ideas

[iggi]

For those haven't done a full gut of their ambulances.. have you modified the factory heating/ac to run from 12 volt?

Travis of YetiAmbo talks about running a webasto coolant heater for his unit and a 12 volt compressor for the AC here:
Seems like that is a better option than tossing the factory stuff and replacing with roof mounted units..

Since my 2009 Crestline is the New Era (which is smaller module) I thought the heat & AC just ran from the cab. But on taking panels off today I discovered not only more unused storage space but also a small Heating (and AC?) unit.
In playing with the thermostat it seems that it is both Heat & AC but neither work with the engine off.

I've been googling around trying to find more info on it but to no avail.
Would be great if someone has a link to the documentation or some insight from their own modification.

Thanks in advance,
Ian

 

[iggi]

Was showing the rig off to a buddy this afternoon. Weather is bloody cold for May so it was a good heater test.
The rear heater (as expected) works from the engine coolant. So, connecting a 12 volt coolant heater into it all will work. Will it be as efficient as a Webasto Airtop? No idea... but it would be multipurpose in that it could also heat up the shower water, etc plus make for easy starts on during the cold Canadian winters.

Rear AC also worked with the engine running, this seems to indicate the rear unit does not have it's own dedicated compressor.
Now, what I know about HVAC systems is practically nothing but wouldn't something like one of these 12 volt mini-AC compressors work?

Online Order - RIGID HVAC - Cooling Specialist. Compact Cooling | Mini Compressors | Refrigeration Parts

Online Order - RIGID HVAC - Cooling Specialist. Compact Cooling | Mini Compressors | Refrigeration Parts

www.rigidhvac.com

There are fairly low BTU but ... since the box is insulated it seems that one could use the engine driven compressor to get the temps down to reasonable and then switch to the low draw 12 volt system to keep the temps tolerable?

Thoughts? Feedback?

Ian

 

[Pman47]

Hate to bring up an old post, but did anyone get anywhere with this?

 

[iggi]

I haven't had time to further explore this. Due to time/budget constraints I've ordered one of the chinese webasto airtop knockoffs and will be installing it shortly. Long term I'd still like to go with the coolant heater for the reasons listed above but recognize I'll either have to replace the current high draw fan or supplement it with a low draw/high efficiency fan for pushing the hot air when running only on battery power.

 

[Feitl]

I own this rig built by Travis.. I cannot seem to find out how he ran the system he explains.. maybe in due time I will find out, but currently I have to run the truck to run the AC.

 

[JP-ADV]

I own this rig built by Travis.. I cannot seem to find out how he ran the system he explains.. maybe in due time I will find out, but currently I have to run the truck to run the AC.

I've been trying to figure this out myself. I posed the question to Quora, but was mostly met with resistance and a lot of "why don't you just buy a mini split or rooftop system". Explaining to them that everything is already there minus a little electric compressor didn't seem to jive with anybody. I think I'll end up with a mini split if I can't figure this out, but I really don't want to lose an overhead cabinet to fit the interior unit and also have to sacrifice an exterior cabinet or mount the exterior unit on the bumper, blocking a door, etc. Anyway, I've not given up on using the system already there and at some point am going to start talking to a few local hvac experts until I find one who is intrigued by the project/challenge and can think more 'out of the box' instead of just saying "duh just get a mini split" instead of giving it any thought.

 

[NWnewbie]

Jumping in to the conversation, I'm just starting to track down what works and how on my newly acquired Ford E450 2006 6.0L w/ ambulance pkg., 21.5 feet, It has an airconditioning unit with wall-mount thermostat (ProAir 925 cool-only, which I found a manual for online) and a separate heater near the floor in the rear (which seems to only have a control on the unit and is not working-- and although the manuals I found for the Fleetpower 1000W inverter w/ remote manuals were helpful, I'm still tracking down funny business with the AC circuitry with shore power).

 

[iggi]

Not 100% sure but isn't the 925 run from the engine driven AC compressor? If so then it won't actually cool from shorepower, but the fan will run)
This is probably the manual you found but just in case it's not. https://www.proairllc.com/pub/media/pdfs/commercial_product_manual.pdf

 

[motofreak0592]

Would you be able to use an A/C compressor from an EV or hybrid vehicle. I swear I read somewhere that someone was trying to use a EV compressor for their campervan or skoolie. I just cant find the forum that I read it on. I dont know much about A/C systems but will have to start on mine soon.

 

[Rebuilder]

I've been dealing with all these things while building my ERV so maybe I can add some insight. First off, yes the rear A/C runs off the same engine mounted compressor as the A/C in the cab and there's no way to run it off shore power. On my ERV (probably the same on most ambulances) there are "service valves" going to the rear A/C which you can close and disconnect the rear A/C unit and you can disconnect the rear heat by removing the hoses and connecting them to each other to divert the coolant back to the engine. My rear A/C and heater unit were combined and I decided to remove them completely and do my own thing but I don't see why you couldn't keep them and just separate them from the engine and add your own hydronic diesel heater and a 12volt A/C unit from AliExpress. Ebay has the same units but much more expensive.

My heating system consists of a hydronic diesel heater which pumps antifreeze to a calorifier (for potable hot water) and then through the floors to a radiator with computer fans. My calorifier has two coils in it which allowed me to run the existing heater lines from the engine through it to heat water while I'm driving. I have a valve system to bypass the floor heating during the summer. You could make this same or a similar system using the existing rear heater unit.

I should preface this next part by saying I just got it installed and running a few days ago so I can't speak to the longevity of the unit but I am happy with the quality of the parts and the performance in the testing I've done so far.
For my A/C system I bought a complete 12v split unit off AliExpress for $617 including shipping from the US. I probably wouldn't have bought it if it didn't ship from the US but it did and I got it in a few days. I've looked into using EV compressors, which I don't think come in 12 volt, and I've looked into building my own system by just buying a 12v A/C compressor and all the parts but I thought $617 was an OK price for a complete and ready to install system. I just had to hook everything up and fill it with R134 and it worked. You fill it just like you fill the A/C in a car so anyone can do it. With that said I don't see why you couldn't buy all the components separately and reuse the existing rear A/C evaporator and fan. To me using the complete kit made more sense. Regarding power usage, it uses between 40 and 60 amps depending on the setting. In my testing it cycled quite a bit so it wasn't continuous amps but I'm guessing it'll be more continuous when the A/C is actually needed this summer.

Here's the A/C kit I used. Looks like the 12v unit is out of stock in the US right now but you can probably find another one that is in stock.



I can post more pics if people think it would be helpful or just check out my ERV build thread linked below.

 

[Rebuilder]

I should also note that I have used the hydronic heater and calorifier to get potable hot water many many times over the past year but I've only tested the in floor heat and haven't got my radiator hooked up yet so I haven't been able to test the cabin heating side. Hope to get some testing in before winter is over.

 

[MrBryan]

So how did it go with the a/c?

 

[JP-ADV]

I've been dealing with all these things while building my ERV so maybe I can add some insight. First off, yes the rear A/C runs off the same engine mounted compressor as the A/C in the cab and there's no way to run it off shore power. On my ERV (probably the same on most ambulances) there are "service valves" going to the rear A/C which you can close and disconnect the rear A/C unit and you can disconnect the rear heat by removing the hoses and connecting them to each other to divert the coolant back to the engine. My rear A/C and heater unit were combined and I decided to remove them completely and do my own thing but I don't see why you couldn't keep them and just separate them from the engine and add your own hydronic diesel heater and a 12volt A/C unit from AliExpress. Ebay has the same units but much more expensive.

My heating system consists of a hydronic diesel heater which pumps antifreeze to a calorifier (for potable hot water) and then through the floors to a radiator with computer fans. My calorifier has two coils in it which allowed me to run the existing heater lines from the engine through it to heat water while I'm driving. I have a valve system to bypass the floor heating during the summer. You could make this same or a similar system using the existing rear heater unit.

I should preface this next part by saying I just got it installed and running a few days ago so I can't speak to the longevity of the unit but I am happy with the quality of the parts and the performance in the testing I've done so far.
For my A/C system I bought a complete 12v split unit off AliExpress for $617 including shipping from the US. I probably wouldn't have bought it if it didn't ship from the US but it did and I got it in a few days. I've looked into using EV compressors, which I don't think come in 12 volt, and I've looked into building my own system by just buying a 12v A/C compressor and all the parts but I thought $617 was an OK price for a complete and ready to install system. I just had to hook everything up and fill it with R134 and it worked. You fill it just like you fill the A/C in a car so anyone can do it. With that said I don't see why you couldn't buy all the components separately and reuse the existing rear A/C evaporator and fan. To me using the complete kit made more sense. Regarding power usage, it uses between 40 and 60 amps depending on the setting. In my testing it cycled quite a bit so it wasn't continuous amps but I'm guessing it'll be more continuous when the A/C is actually needed this summer.

Here's the A/C kit I used. Looks like the 12v unit is out of stock in the US right now but you can probably find another one that is in stock.

View attachment 707579

I can post more pics if people think it would be helpful or just check out my ERV build thread linked below.

I'd like more info, please. I've been looking at those units myself and truckers seem to like them for their sleepers. Most I see run it off a portable generator when the engine is not running. The BTU rating claimed seems like a sweet spot for my ambulance expedition vehicle project where a 8K 120v minisplit seems overkill/oversize and the little portable 12v ones that do ~2K BTUs are insufficient. You mentioned

 

[Rebuilder]

So how did it go with the a/c?

I'm still building the interior so I haven't had a chance to use the A/C for any length of time but I have run it for a few days while I was working inside while still in my shop. I can say with the little bit I've used it I'm very impressed. The days I ran it it was really humid and it was noticeably less humid within minutes of turning the unit on and it didn't take long to get the inside of the camper to a comfortable temp. One thing I wasn't stoked on was the condensation buildup on the metal manifold at the unit and condensation on the outside of the plastic cover. There is a drain tube for the condensation inside of the unit but I see myself needing a towel or something under the unit if I run it on humid days.

 

[Deshet]

I'm still building the interior so I haven't had a chance to use the A/C for any length of time but I have run it for a few days while I was working inside while still in my shop. I can say with the little bit I've used it I'm very impressed. The days I ran it it was really humid and it was noticeably less humid within minutes of turning the unit on and it didn't take long to get the inside of the camper to a comfortable temp. One thing I wasn't stoked on was the condensation buildup on the metal manifold at the unit and condensation on the outside of the plastic cover. There is a drain tube for the condensation inside of the unit but I see myself needing a towel or something under the unit if I run it on humid days.

interested in a similar unit did you use it this past summer much