Attempting to remove part of the A/C. MC9

[TheHeavenlyChillbillies]

Hi there.
My OTR A/C was already disabled when I bought my bus.  It has been verified that there is no r410 in the system.  There are no belts going to the compressor.

I would like to remove the stuff in the side compartment so I can put the outside unit of a mini split in there.

Considering there is no gas already...are there any special considerations I should make?  Or can I just rip everything out.  I mainly want to get rid of the exhaust fan, the radiator mounted to the door, and condenser (if that's what the blue thing is that's hanging from the top).

Thanks for your time.

[richard5933]

I believe that radiator thing is the condenser. The tank is to hold the refrigerant.

[buswarrior]

Yes, remove as you feel led.

The fan motor and shroud may be of interest to someone rolling their own air movement equipment?

The condenser(big radiator) has some good scrap value, especially if it is copper core. Take that to a proper scrap dealer and get some ca$h.

Properly terminate the big cables, and disconnect the other end of them from the controls and big relays. Stuff left capable of being livened up can ruin someone's day in the future...

Happy coaching!
Buswarrior

[TheHeavenlyChillbillies]

Thank you for the response.  Just to double check...nothing in there is plumbed in with the heating system or anything else.  I can just hack away for the most part?

I'm probably gonna get in there with a grinder to expedite the process...just want to make sure there are no coolant lines or anything to contend with?

Thanks.  I'd rather ask now then have a mess later

[richard5933]

Is this a GM or MCI?

Not sure about the MCI, but on the GM the heating system is used in conjunction with the a/c.

The compressor on the a/c system always runs when the system is engaged. Once the temperature inside the bus reaches the set point, the system opens a valve to permit hot coolant to enter the heating system heat exchange unit, which moderates the temperature.

Whether or not that is how your system runs, just be sure that whatever you're tearing out is only connected with the a/c side of things. You'll want to avoid anything that carries coolant/antifreeze for the heating and defrost systems.

The OTR heating system can't be beat, so if yours is working you might want to leave it. You'll also need a defroster, so don't mess with that unless you have an alternative.

I took my bus for tires yesterday with temps around 40F. Amazing how much moisture collects on the windshield as the system comes up to full temp. The defroster is a must.

[buswarrior]

So long as you aren't going thru the wall to the cavity where the heat exchanger and evaporator are. Make sure that back wall is closed up tight, the other side leads to the inside eventually.

I would get the power confirmed disconnected first.

Happy coaching!
Buswarrior

[buswarrior]

Richard

"Amazing how much moisture collects on the windshield as the system comes up to full temp. The defroster is a must."

That's moisture in your coach. Those conditions highlight what the humidity inside the coach is like.

Water getting in somewhere?

Happy coaching!
Buswarrior

[richard5933]

Richard

"Amazing how much moisture collects on the windshield as the system comes up to full temp. The defroster is a must."

That's moisture in your coach. Those conditions highlight what the humidity inside the coach is like.

Water getting in somewhere?

Happy coaching!
Buswarrior

Don't think so. We did have a few minor drips in the past, but they were buttoned up early last summer. I've been watching this fall and winter like a hawk, and there have been no signs of water dripping or getting in anywhere I can see.

It's been my experience that hard surfaces like glass, metal, and stone tend to get really moist when they go quickly from 30 degrees to 70 degrees, sort of like a cold glass left out in a warm room. The relative humidity around here has been pretty high, so I'm sure that contributed to it as well. Being the first time out this year, I suspect it was just condensation from all the cold glass getting a burst of warm air - the engine block heater was plugged in all night, so the heat came up pretty quickly. Things cleared up pretty quickly once I turned on the defroster.

The only place I can think of that might have moisture is the HVAC cabinet, but there was absolutely no smell of coolant to the air coming out of the heat vents, and the levels all check out fine with no red drips anywhere.

[Jim Blackwood]

I'd think carefully before ripping out the OTR system. Even if you never use the engine driven compressor, the other components in the system are rugged and generally over-engineered.  Even with a split-mini system you may find it useful to take advantage of the existing evaporator and air handler.

Jim

[TheHeavenlyChillbillies]

I'd think carefully before ripping out the OTR system. Even if you never use the engine driven compressor, the other components in the system are rugged and generally over-engineered.  Even with a split-mini system you may find it useful to take advantage of the existing evaporator and air handler.

Jim

How so?  What purpose would/could it serve?

[buswarrior]

You are keeping the coach heat functional?

Stock AC needs money and a competent technician, and then more money. Lots of busnuts choose to remove that, and put something else.

However, nothing beats the stock coach heat going down the road, and most attempts (all) made to try to stay warm in winter operations using alternatives, someone onboard is miserable... and then so is the busnut...

The heat lines are not near that outside cabinet.

Happy coaching
Buswarrior

[Jim Blackwood]

Completely aside from the heat which is a major concern, (For peace on the home front, overbuild and do not skimp here.) any AC system has 3 major components: The compressor, the condenser, and the evaporator in that order. And despite all the hullabaloo about matching components the only thing you really have to watch for is making the evaporator too small, which will lead to icing. (disregarding sizing of the TXV or orifice for the moment) Make the evaporator larger? get more of the cold out of it. Make the condenser larger? Eject more heat. Make the compressor too large? Nah, that ain't gonna happen. Not with a mini split. Using a too small compressor otoh means having to match the TXV and then having a slow response time as the liquid line is filled.

So. On the mini split you have a great compressor (extremely efficient) and a relatively good condenser built as a unit. The evaporator(s)? Tolerable. Nothing there to keep you from using the evaporator in the OTR system and it'll suck all the cold out of the freon that's there to get. You might have to swap out the TXV to one about the same size as what's in the Mini-split's evap unit but so what?

The biggest issue with doing it this way is that you'll need a little more freon for the longer and larger liquid line.

In fact, when BW talks about $1000 service what's involved is the freon and the compressor. Yes, belt driven compressors leak more than sealed compressors. How much more depends entirely on the quality of the shaft seal. After almost a century of belt driven compressors, yes the seals have gotten better. So in the end it mostly comes down to the cost of the freon. By the 30lb can r134 is pretty cheap at something over $100 a can so if 410 is much more expensive, switching over can help, and if the TXV needs changed anyway that's just a matter of getting the right one for r134.

Think you can't service the AC? Wrong. Just being bigger doesn't make it harder. Need to evacuate? You have a very large belt driven vacuum pump already hooked up. Just configure the service valves correctly to vent the exhaust to atmosphere. Worried about how much freon to add? With that huge accumulator that most systems have it's hard to go wrong. Put in enough to where the system stops getting colder as you add and stop. My accumulator has sight glasses at top and bottom, there must be a gallon or more of capacity between them. Anywhere in that range will work just fine.

BTW, there's no way that mini-split outside unit will even come close to keeping up with the OTR system. Give that a little thought. Look at the BTU ratings. Is there a reason why MCI was paying for upwards of 80K btu? You betcha. Yes, you can get by with less. Especially if you insulate the heck out of the shell. Plus you aren't carrying around 45 people and their BO. But be reasonable about it. You aren't going to be happy with a 90% decrease.

So quit crying about the expense of AC and learn how to fix it. It ain't rocket surgery guys. (Nope, it's Bus surgery!

Jim

[richard5933]

There are some new 12v and 24v AC systems coming on the market nowadays. Wonder if they hold any hope for bus nuts? Would be nice for OTR use, as there would be no need to run the generator.

[brmax]

In any case a defroster is a required item in a motor vehicle, so it is at least a system that needs to show an air movement around the drivers view. Particularly through factory type vents as this as you know is pretty decent placement to help in the weather conditions.

I keyed in on a great point mentioned, and thats disconnecting the electrics to the big motors your disconnecting. In the 9, mine is the first bay driver side above in a flip down compartment, housing the solenoids.

I am still in a comfortable deconstruction stage and happy to be! so always listening.


good day

Floyd

[buswarrior]

JIm, the reason you need the good technician, and by "good" i mean bus experienced, is to sort out the rest of that (profanity deleted) system without bankrupting you.

Number one system requiring maintenance is the HVAC. Tthe emissions is a challenger for top spot.

If fleets have to constantly worry over this bus hvac equipment... a busnut needs to know what they are getting into.

Many busnuts simply cannot afford to play any games with the stock ac, indeed, ac failure is a triggering event for the last owner to sell. We usually buy broken ac equipment, even if it works for a short while.

Staying comfortable between campsites is a luxery that some of us can't afford. Stationary performance is it.

Figuring out how to eliminate all those flexible hoses and o rings would be a start, but retaining any part of it, you get to retain fleet problems.

Disclaimer, my D3 has working hvac, as did my old MC8, and will continue to, because i will pay to keep it that way.

But, i will be paying...

Happy coaching!
Buswarrior