| Author | Message | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 131 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
My MC9 still has the original drivers defroster, but the bus heat and A/C has been removed. I'd like to install an aftermarket A/C, Heat and defrost unit in the space available under dash for drivers A/C, Heat. I've searched the archives and did not find the specific info I'm looking for: What Red Dot model will fit in the space available under dash in an MC9? Is there another mfg. model that fits in this space? I also want to use a 24vdc compressor so I do not have to add compressor to the engine and I can run the A/C and heat while parked. What size and type of compressor do I need? Thanks in advance for your help. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 1056 Registered: 8-2006 Posted From: 74.33.43.204 Rating: N/A |
I bought units from these folks lot cheaper than red dot and you can buy direct www.discountvantruck.com they have nice furniture also good luck | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 593 Registered: 10-2003 Posted From: 66.165.176.62  Rating: N/A |
This is the local company that does the service on my coach. They specialize in aux AC/heat http://www.welchindustries.com/ | ||
| Rob King (Skykingrob)
Registered Member Username: Skykingrob Post Number: 60 Registered: 10-2006 Posted From: 69.29.89.163 Rating: N/A |
Jim I am looking at these systems, don't know pricing yet. http://www.dometic.com/enus/Americas/USA/Truck/ Rob 91 Prevost XL 40 Missouri | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1190 Registered: 8-2006 Posted From: 99.29.78.69 Rating: N/A |
Jim, What you want, and the way you want to do it won't work well. The truck sleeper cab units are meant to cool an insulated sleeper berth, and don't have the capacity to cool the front of a moving bus. I would ask Sean Welsh exactly how he did the driver's compartment of his Neoplan, as I'm fairly certain he did it electrically. As in the Dometic units, the compressor is actually 120 VAC, powered thru an inverter. You could install a 24 Volt inverter powered from the coach alternator and batts to give you OTR cooling, with changeover to give you cooling while on shore. You will need to install a 120 VAC fan and condenser somewhere, with a high pressure safety switch in the freon circuit, wired in the compressor circuit, to protect it if the fan fails. IMNSHO, an engine driven compressor, with re-sized piping from the bus main heater location to the rear would be a much better solution. You would still need to stash a condenser and fan somewhere, then run your rooftops or whatever electrically while parked on shore or gen. Are you saying that the evaporator (cooling) coil has been removed from the driver's air, but the heating coil and fans are still there? Or just that the compressor and the main underfloor unit have been removed? Whats in the condenser compartment (left side just behind the front tire)? G | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 2038 Registered: 12-2000 Posted From: 174.91.142.13  Rating: N/A |
Who has the BTU figures for the existing dash unit? That might be the best place to start the thinking? happy coaching! buswarrior | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 1267 Registered: 11-2005 Posted From: 75.121.203.118  Rating: |
The original defroster usually has an outlet at the feet of the driver for his comfort separately from the passenger heater. Yours could be closed. There is usually a water valve there also to separately control the def/drv heat separately. | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 132 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Thank you for your responses. To clarify a few issues: The entire coach heat and a/c system has been removed. The defroster circuit and coolant line to the driver is intact. I'd like to build something similar to what Sean has described in his bus. The purpose will primarily for otr a/c for driver and passenger. I doubt that I would use it while parked - unless I had a 50 amp service. George, I meant to say a 120 Vac compressor running off my inverter. Sorry. I have a Trace 4024 so I believe that should work for power otr. I have the house and coach batts connected otr with solenoid. I also have a secondary circuit that allows me to run both rooftop a/c units off the inverter when otr (both circuits set up with Sean's help). Normally only the front a/c runs off the inverter. I was hoping that I could install the 120vac compressor and condenser in the spare tire area and find an underdash evaporator unit that would fit into the area under the dash. I don't want it to intrude into the driver or entry step area. My intention was to continue to use the coolant line for heat and defrost from the under dash unit. I hope all that makes sense. I'm don't have a/c expertise so I'm hoping for advice and guidance from the experts here. Regards, JIm | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1191 Registered: 8-2006 Posted From: 99.48.214.159 Rating: |
Jim, This does clear up your original question, and here's some more ideas, and suggestions. An SW4024 is the ideal inverter, but the first two numbers are 40! Or in other words, its only capable of 4000 Watts. A 13,500 BTU rooftop air with a 10 EER RUNNING rating will consume 1350 Watts, so two will consume 2700. If you were to add a 1 Ton (12,000 BTU) compressor to this arrangement, you would use 3900 of the 4024's 4000 running Watts. As an inverter needs twice the running capacity to start a load, you can see that you can't run all all three at the same time, before we even consider your new condenser fan and evaporator blower. An electric A/C system will require a compressor, a start capacitor and potential relay, a filter/drier, a run capacitor, a contactor, a condenser and fan, some kind of expansion device, (TXV or a piston) and an evaporator and blower, plus a thermostat to control the temperature, and a selector switch to control continuous fan, and cooling/defrosting speed. You will also need a pressure switch installed in the high pressure side of the freon circuit, wired into the compressor contactor to protect the compressor in case of a condenser fan failure. I would also include a low pressure switch to protect the compressor in case of a freon leak. A 20 Amp slow blow fuse in the compressor circuit, and 10 Amp fuses in the fan circuits, plus a 20 Amp HACR breaker in your main panel complete the parts list. Now, you've got to plumb this thing so it doesn't trap oil, or bring liquid back to the compressor. Oil travels with the freon in most all A/C systems. Did I mention free air for the condenser? Also that it can't take in its own hot air again? Thats why I asked about the condenser space the last time. Or, you bolt and belt an automotive type compressor on the engine, run smaller freon lines(to keep the velocity up and bring the oil back) forward, take the high side thru an aftermarket automotive condenser and DC fan and relay in the top of the original condenser compartment, and connect to an automotive type dashboard unit. These have controls for heat, vent, fan speed, AC, and defrost, and one wire for the compressor clutch. This wire still has to go thru the pressure switch, and you still need a filter drier with a sight glass. Google "Old Air," as they are one of many companies making complete in-dash units with complete neat dash mounted controls for old cars and pickups. An engine driven compressor will also give you more capacity than a 1 Ton electric. The electric comp. will cost you $400, and the contactor, caps and relay will be another $150. A rebuilt automotive comp with clutch won't be half that. Then you will need an air conditioning service company to evacuate and charge it for you. Whew, G | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 2041 Registered: 12-2000 Posted From: 174.89.173.81 Rating: |
Is the dash evaporator removed, or sitting in there idle? Either way, the space is there to duplicate it, or use it with a behind the bumper unit down below. I agree, using the stock heater/defroster is a good idea. happy coaching! buswarior | ||
| doug yes (Dougg)
Registered Member Username: Dougg Post Number: 138 Registered: 1-2007 Posted From: 174.131.117.17 Rating: N/A |
MCI installs 24v Carrier drivers ac units in there conversion coaches. | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 133 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Hi all and Thank you! for your help. George, you make an excellent case for rethinking my plans. I don't want to max out (or over max) the Trace - as I might want to do other things while otr that may require the inverter. I'm not sure I have the skills to fabricate and install a compressor on the engine. However, assuming I can get that accomplished... Could I use a pair of the existing copper lines that run up the center of the bus? Those were not removed w/ the otr air and that would save me the expense and difficulty of running new lines. Perhaps I was just lucky, but I built street rods and customs w/ Vintage Air units and they were easy to install. All I had to to was wire it, plumb it and have it evacuated. I guess all of those switches, relays, etc. that you listed were built into the usit by Vintage air? Jim | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1192 Registered: 8-2006 Posted From: 99.184.8.185 Rating: N/A |
Jim, Several people can fab brackets to mount a compressor that will line up with the old AC pulley. If you use an engine driven compressor, you don't need most of the electrical stuff. Just as you say, the necessary stuff is built into the unit by Vintage Air, or whoever. BW is right on in continuing to ask about the driver's air, please take off the front center panel and see if there is a squirrel cage blower there. Then take off the right panel, and see if there are two coils visible, one is the heater/ defroster, the other is the driver's air. The driver's air freon lines run from the front to the location of the bus main air, where they tee into the larger lines that run to the rear. The bus air could be run without the driver's, but not the other way around, due to the driver's air being too small in relation to the stock compressor. Oil travels with the freon, and it will settle out in the suction line if the velocity isn't high enough, which is what I feel will happen if the original 8 ton suction line is used with a 1 1/2 ton compressor. So, the suction line from the main unit back should be replaced with about a 3/4" ID line to keep the oil in the freon vapor. All auto ACs that have a condenser in front of the radiator don't need any high pressure protection, as if the fan broke, the engine would overheat along with the AC going into overpressure. You will need an electric fan cooled condenser mounted somewhere, and if the fan motor fails, or it sucks up a lot of dirt, the high side pressure will go so high it will destroy the compressor. The solution is a pressure switch in the high side that will disengage the comp clutch before the pressure does damage. G | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 134 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Thanks again for your responses. I plan to retrieve the bus this week from its cave. I will investigate what is left under the dash and report back here. Best Regards, Jim | ||
| Rob King (Skykingrob)
Registered Member Username: Skykingrob Post Number: 61 Registered: 10-2006 Posted From: 69.29.89.163 Rating: N/A |
George, et. al I like Jim, have the original bus air gone. I still have the evaporator coils in the front dash but the lines from the rear of the coach, the condenser and the compressor are gone. My concern is how to get new 3/4" copper line from the rear to the front and then sodiering them together after you do. I Googled at both Old Air and Vintage Air, good informtion there. Like Jim, I will have to have someone fab up a bracket for the compressor. I figured that with the cost of copper and all the a/c parts, it would be cheaper to go with electric kits but after seeing Old and Vintage Air, it might be a smidge cheaper to go b ack to compressor but it will be much more work to get it installed, especially the line. I haven't checked but I would guess that having hoses made would be very expensive but they would be much easier to install from the rear to the front. Thoughts??? Rob 91 Prevost LeMirge XL Missouri | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1269 Registered: 3-2007 Posted From: 71.55.183.81  Rating: N/A |
Rob Was going to send E-mail and it ain't there lOL now all the lines usually run down the belly of the coach.Crawl in there and look for a type of tunnel and look to remove it an check er out. Better still YOU PREVO OWNERS CHIME IN HERE!! Gomer | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 616 Registered: 2-2001 Posted From: 184.0.13.120  Rating: N/A |
If the front to back lines are truly gone, there should be two grommeted holes in each bulkhead you could run new copper through. But I'd bet the lines are still there. Few people are going to go through the hassle of removing them. But the lines will be way too big for just the driver's air. You might find that the old liquid line might be close to the right size for a suction line & you can run a liquid line sized properly for the new system. If the old lines are there, you might be able to push the new liquid line through the old huge suction line. If it were me, I'd use hard tubibg with short hoses at the engine. The other components don't need hose unless there is movement, like a swing out condenser coil. Hoses leak & deteriorate. Loooong hoses leak a lot more. Plus, they are larger diameter than the tubing & more prone to being cut or snagged. Just my $.03 worth. | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 136 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Hi all, Retrieved the bus and pulled the panels under the dash. I still have the squirrel cage fans, a heater core and a/c coils intact. The fresh air vent is stiil there although I don't know where the fresh air would be coming from as the front of my bus is now figerglass - no ss anywhere. So, can I use these existing components with an engine mounted auto type compressor? What size or type (?) of condensor assembly would I need? Finally, I'm hearing that a pair of the original copper lines that run front to back cannot be used. Can someone definitively explain why? OR do i need to yank all this old stuff and find a new under dash unit that will fit? Thanks! | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1194 Registered: 8-2006 Posted From: 99.172.182.105 Rating: |
Jim, Jim Bob's advice is worth at least a nickel, freon line size is important, as the line must be large enough to let the freon gas/vapor thru, and small enough to keep the velocity up so the oil travels back to the compressor. The line sizes are right between the front and the main bus A/C location, then probably too large from there back for driver's air only. I would keep the driver's heat/air/defrost if I were you, as it all fits and will work with hot water and freon supplied to it. This is my preference, a Vintage Air or equivalent will work well, just get the largest one made that will fit! The condenser answer lies with Vintage Air, Red Dot, or one of the other aftermarket suppliers. They will be able to point you at a condenser that will match the compressor you buy, and you will have to equip it with an electric radiator type fan to cool it. What is in your condenser compartment now? This will only take up part of it! Next question, what type of refrigerant did your bus have? (Either R12, R22, or R134a) We need to know this so we can adjust the AC HI/LO switch settings, and change the driver's expansion valve. Enough for now, here's tomorrow's homework. G | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 140 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Thank you very much. Homework assignment accepted. I like the idea of using the existing fans/heat and a/c. Just to be sure I understand the terms, the a/c coil that is under the dash is the driver evaporator, correct? The heat core I saw seems small is that intended to be both heat/defrost or just driver defrost? My genset now occupies the original condensor compartment and my house and genset batteries now occupy the oold evaporator and blower location. The manual specifies Freon 12 or Freon 500. you wrote: The line sizes are right between the front and the main bus A/C location, The main bus a/c location is the condensor or evaporator area? Can you suggest the make, model and specifications of the compressor I should buy? Regards, Jim | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1271 Registered: 3-2007 Posted From: 71.55.183.81 Rating: N/A |
Jim You can use the existing coils for the heat without any problem. While you have it tore out rebuild the blower motors,bearings and brushes. George and Sean and others can help on the compressor specs. I had a 4106 with OTR a/c and used 2 GM compressors parreled,A-6's the worked great. Gomer | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1195 Registered: 8-2006 Posted From: 99.172.182.105 Rating: N/A |
Jim, You are correct, it is the driver's evaporator, and the driver's heat and air. The heating coil is large enough to heat the driver's area of the bus. R12 or R500 is good news, as R134a which you will want to use has essentially the same pressures, and will work with the existing expansion valve. Off the top of my head, I don't have a particular compressor part number, my suggestion would be a "replacement" compressor for a 5 year old pickup truck, from Pep Boys, Kragen, or the equivalent. An A-6, also known as a wobble plate, would be fine, they were used on most GM cars and trucks from the early 60s to the late 70s, but they may be getting expensive and hard to find, as most of the cars they were used on are gone. We don't need to worry about the liquid line size from the condenser to the evaporator, as the freon and oil are mixed as a liquid. The sizing is important from the compressor to the condenser, and from the main bus evap. location to the rear. The suction line from the evaporator to the rear must be insulated to keep it from sweating, and from picking up excess heat load. G | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 141 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
George, Are there any specifications that I need to look for? flow rate? size? capacity? - do they come in different sizes? I googled a site for a/c compressor for an '06 Silverado - about $260. Sound about right? It sounds like I will have to run new lines from engine compartment forward. Should these be copper lines or can I use a/c hose? What size copper lines or a/c hose should I use for each line? Thanks. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1196 Registered: 8-2006 Posted From: 99.172.182.105 Rating: N/A |
Jim, Sounds about right. The size will be right just by being what it is. There are different sizes, as obviously a small car will have a smaller compressor. If your supplier has sizing info, try for the largest you can find, but a full size truck comp is going to be fine. We will have to do some thinking on pulley diameters, as our Detroits idle slower than a gas truck, and cruise a lot slower also, so the engine pulley will have to be larger than the compr pulley. About a half inch ID line from the compr discharge to the condenser, 3/8" ID from the condenser to the front, and 3/4" ID from the end of the suction line from the front to the rear. New A/C hose is fine, the older hose was permeable, and 134a would go right out through it. It will take barbed fittings on the end of the tubing, as the high side pressure is enough to push a hose right off the end of plain copper tubing fittings. I also feel a run of that length will require adding about 6 ounces of oil in addition to the new compressor's charge. Nick Badame, are you looking over my shoulder I hope? Another thought is a 24 Volt clutch coil, or do you have a 12 Volt house alternator? Isn't this fun? (But we do want it to work!) G | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1279 Registered: 3-2007 Posted From: 71.55.183.81 Rating: N/A |
George; I don't know about a 24 volt clutch, however, When I ran 2 of the A-6 Compressors, I had 24 volts and just ran them in series and never had any problem with them. The pulley system was altered to accomadate the lower rpm's so they would run a little faster at cruising speeds. Another way is using a Vanner or 12 volt supply from the inverter but I don't like that way of hooking it up. I also used the existing lines that were in the coach and had to set the expansion valves to accomadate the coils.When I got finished it worked great! If the lines look too bad then I would run new lines but The old line was a higher grade than they use now. Gomer Gomer | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 143 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
I believe the alternator is the standard 24volt dc that would be common on MCI MC 9 coach. Engine is 6V92TA. Using the old lines (if that is reaaly feasible) would be preferable to me than running new lines. However, I have next to none in the way of knowledge and experience with HVAC - as I'm sure you can tell by the elementary questions I ask. I need very specific instructions if this is going to work. Thanks again for everyone's help. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1281 Registered: 3-2007 Posted From: 71.55.183.81 Rating: N/A |
Jim See if you can mearure the od of the existing lines. The suction line will be the largest and the liquid will be the smaller. The chances of using the liquid line for the suction line and then putting a smaller line thru the old suction line is quite possible as not having to open the belly up and running it. Hop this is clear as mud!!lol Gomer | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 144 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
Thanks Gomer, That's clear enough! Thanks. There are A LOT of copper lines running through the center of the bus. I counted a dozen or more that I can see. I think there are parts of the original a/c lines from the compressor location in the engine area that I can follow forward. Do you have any idea where I might find the termination of the lines in front? Regards, | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1282 Registered: 3-2007 Posted From: 71.55.183.81 Rating: N/A |
I believe they are terminate below the defroster area. Look at the lines under the stuff,probably from the door on the right side of the dash. You will find a line that probably has some insulation on it and that is the suction line. Also check in where the old a/c condensor and motor was and see if there are 2 lines in there. if they are not capped off they need to be. If there is no OTR heat, the lines may be opened also. they are on the other side behind a wall 1st compartment on passengers side. Keep looking and any questions. bring them on, George will answer them LOL Maybe Nick will chime in, He is about as good as me George LOL HELP NICK DON"T HIT US TOO HARD!! Gomer | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1197 Registered: 8-2006 Posted From: 99.172.182.105 Rating: N/A |
For definitions and sizing: The smaller of the two lines from the compressor discharge to the condenser, located between the front of the front bay and the left tire is called the hot gas line. The line from the condenser which tees to the main bus evaporator and the driver's evaporator is called the liquid line. The suction line runs from the outlets of both evaporators to the suction side of the compressor. There will be a solenoid valve in the liquid line to the driver's evap for sure. You will have to install a filter-drier with a sight glass and a pressure switch in the liquid line leaving the condenser. The sight glass will indicate how much to charge the system, the filter-drier portion keeps the system clean and dry, and the pressure switch protects the compressor in case of a condenser fan failure. The switch wires in series with the compressor clutch wire. Thinking about this a little more, there is an AC HI/LO light on the dash, which is connected to a commercial type pressure switch which should protect against both high and low pressure problems. Look for it either near the compressor, or up in the condenser compartment. G | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1285 Registered: 3-2007 Posted From: 71.55.183.81 Rating: N/A |
Thanks George LOL I knew I was missing something..... again!! Gomer | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 148 Registered: 12-2009 Posted From: 69.152.168.208 Rating: N/A |
George and Gomer, Can I use the exterior cam driven pulleys that are on the 6v92? They look to have about the right width grooves - vs the huge pulleys on the engine. What size pulley should I have on the a/c compressor? assuming I use the a/c compressor below? Would this be a good a/c compressor candidate? http://www.discountacparts.com/Chevrolet-Motorhome-A_C_Compressor-60~01552_NA.html Jim |
