Over The Road Air Conditioning

[buswarrior]

Stan, did you sell those to me in Peterborough, back a number of years?

Big factory conversions have 5 roof airs, because at that price point, I'm not waiting for the coach to cool down if it has been parked in the sun. There is NO EXCUSE for the AC to ever not cool the coach in a noticeable way. No waiting. Excess capacity is part of the price of entry.
Bragging rights to make up for hidden inadequacies might play a part as well...

Riches have their rewards, and their expectations...

In commercial use, think band/entertainer/VIP bus,  if there is a failure in a unit, there is redundancy and the coach can continue until it gets the time or to a location convenient for service (or is just left for the next user/owner by the less reputable leasers)

I was told, can't remember the source or the validity, that openings the equivalent of a 4 inch round hole would defeat our busnut efforts at AC, due to the air infiltration issue. Easily that kind of opportunity at the front of the coach, pedals through the floor, defroster, suction around the door is massive, through the electric panels beside the driver, the gap around the old door opening pushbutton on the front, the old air intakes on the sides, and out around every window seal, slider, crack and crevice.

Lots of places blow in by pressure, lots of places suck out by vacuum, due to the coach punching through the air.

Another reason the stock system was sized so large? infiltration, pull down and 39/41/43/47/55/56/57 people all living, breathing and sweating inside. Oh and the driver.... A busnut has only removed the large number of people, the rest of the loads remain.

happy coaching!
buswarrior

[Sojourner]

I have gotten Red Dot units out of a 15 year old school bus for free because those in Florida convert them into "goat" units for orange pickers. You could look up salvage yard for roll-over or badly front end damage or coach body already removed from chassis. It is a large unit that sets next to driver and another heater unit near above the rear dual wheel. School buses are very hard to cool & heat due to thin wall or no insulation and never ending infiltration....in other words their heating & cooling are bigger to accommodate the coach design.

I would be sure all leaks are stopped before changing to larger unit.
You can find leak the easy way by temporary attaching a discarded furnace blower on top of overhead vent or escape hole. Close all vents & heater air valves, then pail of warm water with ¼ cup of dish washing soap. Take a sponge mop with handle and apply the soapy water over joints (seal, metal, and fiberglass) and look for bubbles. You can use portable hand-pump pressure tank to wet-spray over what mop can't do. You will be surprised how many leaks you find.

FWIW

Sojourn for Christ, Jerry

[Lin]

I noticed in this posting that several have mentioned putting equipment in the spare tire compartment.  Does that mean that you are running without spare tires?  If so, what is the logic, and if not, where do you put the tires?  Thanks

[Lee Bradley]

Lin,
There was a poll on spares; you can see the results and comments at

http://www.busconversions.com/bbs/index.php?topic=7148.0

[Paul S]

Bringing this topic back to life - would the consensus be that either using the coach AC or a Red Dot unit would be the way to go for over the road?  After going through the maintenance manual I was enlightened to realize the factory coach AC was 90,000 BTU's 

No wonder my puny 14,500 Furrion roof unit couldn't keep the front below 80 going down the road.

[buswarrior]

All it takes is money to make the coach HVAC work as intended.

And then more money...

That is why many busnuts remove the AC bits and design alternatives.

Happy coaching!
Buswarrior

[richard5933]

Always a controversial subject. Here's my 2 cents worth...

If you have a OTR a/c system which is largely intact and which won't require too much effort and/or money to get and keep running, it can't be beat. Otherwise, unless you have an endless budget, look for other alternatives.

We were fortunate enough on both of our buses to have working OTR a/c systems. Our current bus was fully functional but for the compressor, and our compressor was not difficult or expensive to replace. The system was returned to fully functional (both heat and a/c) for about $3500, including a full recharge and a new compressor. Now it will turn the bus into a meat locker on a 90-degree plus day.

Were the system to ever take a deep dive, I'd be looking to other options. If you have a good working generator then your options are pretty wide open, including a pair of mini-split units or a pair of repurposed commercial refrigeration units like we have on our house systems. If you don't have an adequate generator, then the cost for one needs to be added to the mix.

Of course, there are options using inverters and a large battery capacity as well.

[windtrader]

Consider the following fact - Restoring service on a typical roof air unit experiencing problems will be quicker and less expensive due to availability of parts and service than that for a 40 year old commercial passenger bus.

[chessie4905]

Unless you want another money hole, don't  fool with it unless it is 1990 or newer. For what Richard has spent, for example, can buy 4 or 5 rooftop airs. Rarely do the majority of them require annual freon replacement or service. Add a bigger unit upfront and use the curtain idea to isolate the rear 3/4 or 1/2 of coach. Don't forget all the crud in the ductwork of the factory hvac system, which you'll  never get completely clean. If you are starting a conversion, have the interior foamed before starting. That will reduce a lot of heat load. Probably a couple hundred dollars to service and add freon every year, and some freons are being phased out. You can run a generator going down the road for ac or use batteries and inverter, whichever you prefer. Also depends on how many miles you will be travelling every year in hot weather. Two or three hundred hours a year, then the factory system makes more sense. Driving into the sun is hot with a good hvac even in a car, due to radiant heat.
In a few months, we'll  be talking about how to keep warm in the coach.lol🤔

[Jim Blackwood]

I love all the speculation about OTR air by owners who don't have OTR, etc. Tends to be good entertainment. But I have a serious question about the compressor. What is the correct procedure to add crankcase oil? Is the crankcase pressurized?

I just added about 15lbs of r134 to my OTR and it was just barely enough to bring it up to the lower sight glass in the accumulator. Pressures were 50/225. Should it have a couple more lbs? If so what are the max pressures I should watch for?

A 30lb tank costs about $100, cheap for keeping the OTR air. I could handle that once a year.

Jim

[buswarrior]

Just be sure that your camping HVAC can pitch in to help, when there is a failure on the stock HVAC. It won't crap out at home in the driveway...

Empty system takes the whole bottle.

Compressor shaft seal, aged hoses, decayed o-rings, corroded condenser, half-assed repairs by previous owners, rubbed through metal piping from rubbing...

Once those are overcome, it's good until the usual busnut sitting around dries the seals and you start again.

Been there, done that, and will do it again.

Nothing performs like the stock HVAC.

Park in some wide open sunshine venue parking lot, closed up and heat soaked, the usual busnut solutions will take well into the night to cool the coach interior when you return after a day of recreation.

And the Admiral is not enjoying that...

happy coaching!
buswarrior

[richard5933]

Ours took an entire bottle as well to bring it up from empty. Just shy of 30 lbs.

[Oonrahnjay]

...  Another possibility would be a mini split, although not meant for vehicles, with the inside section mounted above the windshield or on the side right behind the driver.  A 12,000 btu unit will run off 120 volts.  If your generator is set up for 240 volts, you could use a 18,000 btu model.   I suppose the easiest option, though, would be another roof unit (15,000 btu) mounted close to the front and ducted to right above the driver to cool the area heated by sun on the windshield.  Good luck with it.  Let us know what you decide to do.  Being hot and driving for hours really sucks.   

David

     Hi, David.  You're right about these possibilities, but I'm pretty sure that I remember Clifford ("Luvrbus") who writes on this forum has said that you need to have at least 48K Btu to keep the average bus cool going down the road.  Of course, it the bus is unusually non-air tight and/or poorly insulated, you need to go up from there.  That's why you see the "entertainer" coaches from Nashville with 5-6 12K Btu units on the roof.

[chessie4905]

Speculation??😚

[chessie4905]

Speculation??😚