TimSpencer

An electric compressor could be used. Without matching it to the metering device and coil it would not work properly. Matching the btu output of the belt driven compressor would be the best option.  An inverter driven compressor or better yet condensing unit(compressor and condenser coil) would be even better. Controlling all this would take a few minutes to get working correctly. The engine driven compressor is not perfect but it is well designed and already controlled. Replacing refrigerant hoses is not fun or particularly easy but it is a far cry easier than redesigning the coach hvac system. Maybe trying to package a system like this in the dash area would be a better option. This would eliminate/replace the current system.  https://www.supplyhouse.com/Sanyo-26UHW72R-24000-BTU-Single-Zone-Mini-Split-Concealed-Duct-Heat-Pump-Air-Conditioner

It is all dependent on what you are willing to live with. If you look through a Sanden compressor catalog you will see compressors with even higher capacities. I would imagine automotive systems are designed for very quick recovery which requires more BTU capacity. No one wants to wait an hour for their vehicle to cool down on a short drive. I was matching the most likely capacity of the existing compressor. You can find many 12vdc compressors with reduced capacity. Try Rigid Hvac and condensing units. Not a big issue to build just not the most cost effective. https://www.rigidhvac.com

A typical automotive A/C compressor is between 3-5 tons of cooling. Motor home application may be even higher. The compressor would need a40-60A AC circuit and the generator would need to be capable of double to triple that capacity for the in rush starting capacity. Using an inverter type condensing unit would be a conversion but would also require the indoor fan coil as well. No always the nicest look. I would guess the replacement of the refrigerant hoses would be a much simpler and cheaper option 

You can try this. A little thicker and sticks to everything. 
https://www.amazon.com/Shurtape-ShurMASTIC-Outdoor-181B-FX-111163/dp/B01M6ZV9BA/ref=mp_s_a_1_3?adgrpid=66119376617&gclid=EAIaIQobChMIkZ7Jt5-0-wIV5hvUAR1VVQNzEAAYASAAEgJ-m_D_BwE&hvadid=617070353227&hvdev=m&hvlocphy=9009922&hvnetw=g&hvqmt=e&hvrand=16469413572864729902&hvtargid=kwd-355527657505&hydadcr=12190_13376095&keywords=butyl+foil+tape&qid=1668654796&sr=8-3

Good to know the sequence of operation. I would add a small electric fan for the condenser to prevent “forgetting” to shut off the dash air. Could be triggered by the radiator temp or just on when A/C is one. Great to hear you located and fixed all your refrigerant leaks. To bad you had to replace the compressor. 

If you have room to operate you could use a torque wrench like this. But most mechanics would tighten by feel. 
https://www.amazon.com/VANPO-Adjustable-Accuracy-Indicator-Torquing/dp/B09XKCJD1T/ref=mp_s_a_1_2_sspa?content-id=amzn1.sym.a6428403-8a18-479d-9f6e-31f0b2c26f13%3Aamzn1.sym.a6428403-8a18-479d-9f6e-31f0b2c26f13&keywords=hvac+torque+wrench&pd_rd_r=8b778c08-7b15-4d9f-ba13-7b4cb1460a34&pd_rd_w=SGd20&pd_rd_wg=UrzVN&pf_rd_p=a6428403-8a18-479d-9f6e-31f0b2c26f13&pf_rd_r=E3QS8GT8N49TM365690N&qid=1667830107&sr=8-2-spons&psc=1

The above mentioned product is a great product and works well. I use Loctite 515 on o-rings on large equipment, recommended by Trane for all o-rings. It can be problematic on threads as it’s anaerobic and locks up like glass without oxygen. As long as the fittings aren’t damaged a new correct sized o-ring with assembly lube should be leak free. Inspect everything before reassembly. 

I would do exactly what the last couple posters suggested. Top off the charge if leak is small and frequency to top charge doesn’t increase dramatically. Taking into account that it will leak while in storage or on the road. 

David has it correct. Lots of variables depending on the designer of the system but automotive and RV systems are fairly basic. Receiver/drier has to be on the liquid line as it stores a bit of excess refrigerant and filters the refrigerant. Liquid is metered through the expansion valve into the evaporator. The liquid is vaporized lowering its pressure and it then can absorb heat from the air coming across the coil. This vapor then returns to the compressor. The compressor compresses the gas raises its pressure and corresponding temperature. This hot gas is then sent to the condenser where the heat is transferred to the air coming across the condenser coil and condenses the gas back to a liquid. And the cycle repeats. Line sizes in automotive systems can be tricky as the rubber hose outside dimensions don’t always give an idea of the actual inside dimension. But at the compressor the larger “cooler” line is the suction line from the leaving side of the evaporator the liquid line from the condenser to the expansion valve/evaporator is much smaller and the discharge”hot” line from the compressor to the condenser will be somewhere in between the suction and liquid lines. I’ll look for a pic to show a refrigeration system. 

Most automotive systems use a low pressure switch only. A high pressure switch could be helpful but not always installed 

Moisture is the toughest thing to remove from A/C systems. This is why nearly all systems include a filter/drier. Nitrogen can help to dry systems. But sometimes it takes a couple times of alternating nitrogen the deep vacuum. Anything that holds or attracts moisture should be avoided if possible. It seems these systems get neglected since there are alternative cooling systems. I have not used this brand but it’s very similar to the Calgon setup I use. 
https://www.amazon.com/HVAC-Guys-System-Flush-Refrigerant-Based/dp/B09XG6X77M

Alcohol is not the “best” line flushing agent. It can attract water. There are line flushing chemicals available that do a better job. Be sure to disconnect  or bypass the metering device and compressor before flushing and always blow out flushing chemicals with nitrogen. Always use nitrogen to pressurize and leak check as well. Take some time to leak check it will pay off in the long run. 

Most compressors have an internal relief. If discharge pressure is to high it bypasses to the low side. Makes an odd whoosh noise. Hoses can definitely leak. Soap bubbles, refrigerant detector, dye, etc can be used 

Easier and cleaner. Take a couple days to get. 
https://www.amazon.com/Qagea-77750-Filter-Cutter-Cutting/dp/B09XQFM4M8/ref=mp_s_a_1_5?crid=2CMATCOXS240B&keywords=oil+filter+cutter+tool&qid=1666306579&qu=eyJxc2MiOiI0LjQ1IiwicXNhIjoiNC4zMSIsInFzcCI6IjQuMjYifQ%3D%3D&sprefix=oil+filter+cutt%2Caps%2C165&sr=8-5

Lots of variables. Easy button remove refrigerant then add factory recommended charge. Check pressures and temps and sight glass if equipped. Add refrigerant to clear glass. If everything else in the system is working then you should be good and it will be cooling properly. If pressures are not where they should be then further troubleshooting will be needed. I would guess the A/C system designer got it close enough to work correctly, nothing is perfect always some compromise 

17 hours ago, Gary Cole said:

If you are going to top off a system without drawing a vacuum and you know the recommended charge then you can bleed off the existing charge to within a few lbs of positive pressure and then add the recommended charge. A slight overcharge to ensure that the evaporator is flooded with freon for maximum cooling  is preferable to an undercharge. The accumulator and  hose length will ensure that no liquid freon reaches the compressor so long as one exercises discretion. You can use the frost on the fittings as a guide to how much freon you have in the system.

Not the best way. You can look at system pressures and temp to get a better idea of the charge on any refrigeration system. “Bleeding” refrigerant is just a waste of expensive refrigerant. 

1 hour ago, trailmug said:

If using dye, make absolutely certain it's compatible with PAG.. mineral oil dye will do this (I believe what happened to mine):

Definitely looks overheated and contaminated for sure. Kind of the chicken or the egg. Did heat deteriorate the oil first or did the dye break the oil down. More likely high temp/pressure or low refrigerant charge(from leak) oil not returning from evaporator and compressor running out of oil and burning the small amount of oil left(my first guess)

16 hours ago, Rikadoo said:

Soooooo please, knowing about ac systems can be a challange!!! That all ac systems are of the same design, oil travels with freon. That said when a system is “FULLY” charged the oil travels with the freon, NOW, as a system drops in freon the oil which was trying to flow ONLY was able to travelfor as long as the freon supply could take it. When i get a … low system, i first recover what is in the system, i then pull the system into a vacume, add 2oz of dye, then charge to spec, turn system on, let run 20 min later, measure high side / low side… then look for “wet spots” if nothing shows the oil is not invisibul, if its leaking, you will see accumulation. My personal favorite is to drive it a couple days using the ac, get your nose to smell whats comming out of the ducts, does it smell good or ??? If it smells ??? Then what I do is to drill the evaporator case, ( know where your drilling) then use a borescope an look at the evaporator, if i see “the wet spot” i know to replace whats leaking! And quit guessing what it might or “could” be i apologise for being blunt, so many want it to be a mystery, an times it can be, however if your freon has had dye mixed with it it, you CAN find the leak… but dont not talk about the  elephant in the room, you need to put eyes on your “hidden” componet the evaporator

I’m not a fan of dye but searching all portions of the system is vital. By any means. Dye, leak detection meter, etc. 

Definitely could have happened. Relays and any set of contacts can fail in a million ways. From the contact melting, dislodging from the holder, bug between the two contacts, moisture, dirt,(I have  experienced all of these and a couple other odd failures over the 3 decades of work with this type of relay and many larger types).
Great job tracking it down especially since it was intermittent.  These things wear out so good to have some good spares. 

On 9/18/2022 at 6:07 PM, On_the_road said:

I have been chasing a problem with my remote lock/unlock system.   Perhaps one in ten times the driver side lock fuse would blow.   All the other 9 times it worked OK.   Today I figured I would chase the problem down.

It turned out to be the Bosch relay that controlled the unlock circuit.   Looking at the schematic, it seemed unlikely to that a relay could cause the fuse to blow.   I unplugged all the lock actuator motors in the basement doors, leaving only the relay and the wires as possible sources of the problem.  But the failure persisted.   Here is what I found:

This is the bad relay, a genuine Bosch!

 

There is a piece of metal wedged between the contacts.   The relay still worked 9 out of 10 times in this condition.   The reason the fuse would blow is that the normally open contact is connected to 12 volts and the normally closed contact is connected to ground.   When the fuse would blow, the particle must have shifted such that the normally open and normally closed contact would both connect to the armature, resulting in a dead short and a blown fuse.   I have pointed to the metal particle.

 

This shows the contact of the armature with a hole in its surface.   I have pointed to the actual metal particle.   The particle is almost certainly the metal from the hole in the contact.   The contacts are made from silver.   The plastic cover of the relay fits very tightly, so it is unlikely that the particle came from the outside.

 

This is a microscopic image of the contact that shows a hole in its surface.   The hole is quite deep.   I have never seen anything like this.

 

 

It looks like normal wear. Unless this relay is only been in use for a short time. If relatively new increase the amp rating of the new relay. Every time it opens/closes there is a bit of lightning bolt as the contacts approach each other. A bit of a welding arc. Eventually the contacts pit any can shed tiny metal droplets. Nice work tracking it down. I always have a couple of those relays in my spares. 

9 hours ago, cbr046 said:

My dash AC worked on the way to my destination Friday but not the way home Sunday.  Got tired of running the generator so pulled into a Lowe's 200 miles from home to add a can or two of refrigerant.  With the AC on max I had 110 psi on both hi and low sides (static).  The compressor wasn't running . . . . but why? 

Got to it today and able to read up, open the rear hatch, watch the compressor, short the pressure switch and add 36 oz of R134A (yeah, a lot!).  Final pressure settings were 30 low / 150 high with 55F at the louvers.  Ambient was 80F. 

The biggest question is whether the low pressure switch is going bad or was it just a case of low freon?

Got another trip this weekend . . . .

- bob

 

 

If you have 110# and you jump low pressure switch, it’s a bad switch. 

1 hour ago, Ken Thompson said:

Since the older ISL with the CM554 is near impossible to find, just wondering, why I can't take any year ISL 8.8 or 8.9 engine and use my bolt on components, like the exhaust, intake, ECM, etc.? Since the main block is the same. Am I just an idiot?

That sounds possible and would be a heck of a lot simpler. 

I would try to buy engine with its original ecm, rewire as needed. Radiator maybe something that is a wait and see. I would definitely send it out for cleaning and pressure testing and if shop feels there is an issue then  upgrade. 

Not having made this particular engine swap but having done several others in my life. If the engine can physically be attached to the trans and chassis the hard part is done. Now assuming you have everything needed to run the engine (ecu, fuel system, exhaust, etc) you just as Monaco did will need to sort the wiring. Original wiring print and new print. All the connectors should be available if a conversion harness is easier or you can depin your original connectors. Sorting through the wiring prints can be done well ahead of time. As far as can the trans take the extra power and torque only Allison or time can tell. I think we all would like to know how it works. Good luck 

You can try adding a pan treatment tab to help with cold water slime build up. 
https://www.amazon.com/Nu-Calgon-4296-60-Pan-Treat-Scum-Tablets/dp/B003N5AS60/ref=mp_s_a_1_8?keywords=a%2Fc+pan+tabs&qid=1662666702&sr=8-8

Everyone has now graduated to HVAC specialists. Great job on both coaches.