[Dale]

Ken,

You have OTR air if you have a large compressor on the lower RH side of the coach and in the third bay back you have a large condensing coil mounted on the RH side door and an evaporator coil on the LH side door.

To operate the OTR you should have a three position rocker switch that controls the entire system, along with a temperature control knob. The rocker switch is for whole bus AC in one position, whole bus heat in another position, and the center position should be the off position.To operate the dash air there will be a knob that has an off position when turned fully counter clockwise, and increases the dash air flow as it is turned clockwise. There is a second knob to control the dash air temp. You cannot get cooling from the dash air unless the main OTR system is turned to the AC position. You can get heat from the dash air controls without the OTR heat position selected, but the circulation of engine coolant to the front heat exchanger will be better with the OTR heat position selected.

You don’t mention if you have roof or Cruise Airs, but I suspect that vintage coach may have cruise airs located behind the bumper. There are many reasons why one will not work so a lot more information is needed before even beginning to suggest possible courses of action.

[Archived]

Yes I see what you are referring to…. so I guess it has over the road heat and air…. which both seem to work….

It also has 3 cruise air units… the front unit seems to run fine but not cool…. the fans kick on but not cool. It also has 2 buttons in the rear of the coach int he DC distribution panel labeled 12V heat and 110V heat… I kicked both those on, and then spun each of the 3 thermostats under the 3 cruise air controls but don’t seem to get any action on anything, no fans, no heat… I must be missing something…. I know when I open the rear side engine door there is a large long box labeled “Webasto”, and there is also a 120 breaker labeled Webasto, or maybe it is a dc breaker… in any event, when I hit the 12V heat and 110v Heat buttons nothing seems to happen even when the thermostat calls for heat….

[Archived]

I suspect based on your descriptions that your Cruise Air controls are the type that uses three black knobs. If so that means they are not heat pumps, but strictly AC units.

As to their performance the first step is to turn them on and using thermometers or an IR gun check supply and return air temps. If the spread is greater than 15 degrees they are functioning well. It sounds as though the front one on yours is not working properly. It may be as simple as the R-22 freon charge needing adjustment or it could be more serious.

Perhaps an early model Marathon owner can jump in and address the heat source. It could possibly be toe space heaters but I lack Marathon knowledge.

[Archived]

Must have missed it but what general part of country you located. Might be help right around corner. Bob

[Archived]

as am I…. I definately have 3 round knobs on my cruise air units. Marathon said they do have heat pumps, i.e. heat down to about 40 degrees or so… but people here are saying no… asked Marathon to clarify…. I really need to gain a better understanding of this heat issue… winter is almost here, and I need to work through the winter to finish this coach and heat is a must….

I found the 12V and 110V buttons in the bedroom… I know the 12V runs the Webasto System, but what does the 110V run? should I be hearing fans run? i’m not…. where would the “warm” air blow from?

this is a 89 Marathon conversion… maybe this is a dumb statement, but the coach has no fresh water in the tanks…. does the Websasto require this? where does it get it’s fluid?

Anyone have a diagram or manuals on this Webasto System? Searched the web but couldn’t find them… previous owner said the one in the coach is new….

[Archived]

I don’t believe the controls you have support a heat pump. I think the SMX controls were for heat pumps.

What kind of a check out did you get from the previous owner, and what kind of a pre-purchase inspection did you do before taking possession? That is when most of these questions and system training get resolved. Have you considered calling Marathon?

[Ken]

Ken,

Given Marathon said you have heatpumps, you likely do. As much as knowing this information will be helpful, heat pumps aren’t effective as temperatures drop; as you state near 40 degrees. If you are working outside and the temps are 40 or below, use your Webasto or electric heaters. The only down side the the Webasto is that you must be outside and the need to have diesel fuel available.

The Webastco system pushes hot fluid through heat exchangers in the living space. Fans push interior air across these heat exchangers to move the heat. You should have fan controls. These are either independent switches or a function of your Air Conditioners thermostat. If your thermostat supports this it will have a setting for furnace. I believe you have said that the Webastco turns on with the 12V switch, but you can’t feel any air movement at the heat exchangers. The air movement may be slight, so put your hand over the heat exchanger. I’m sure there are other clever ways to make the heat exchanger fans work. I’d ask Marathon. If they don’t know, which is unlikely, find someone that does or at least fully understands what converters were doing at that time.

Rick May at Coach Worx in Clearwater, FL knows these systems well. Give him a call.

Best of luck and stay warm.,

[Rodger]

How much fuel dose a WABESCO use i was told 2 gal per hour when i was buying my coach sound like a lot

[Bob]

The typical 40,000 BTU Webasto will burn up to 0.34 gal/hour (standard burner nozzle) when running full blast.

[Steve]

On our Marathon the Webasto heat exchanger fans are controlled by the same thermostats as the electric toekick heaters (Cadet) plus there is a dedicated thermostat above the passenger seat. Turn on “12V heat” and adjust the Honeywell thermostats to call for heat and off you go. If you have a “High Heat” button it will run the heat exchanger fans in fast (noisy) mode.

[Ed]

Not sure I’m seeing these???? the coach is gutted from kitchen forward, and I can see the factory plywood that seems to cover a long metal box that runs the length of each side of the coach from front to rear. It isn’t for wiring, since the wiring is inside from what I can tell some type of plastic tubes….. I don’t see any vents from these metal boxes or ducts… where would the toe kick heaters be?

[Archived]

Pics of Control

[JIM]

[Andre]

Those Cruise Air controls are for AC only and there is no heat capability from those units.

[JIM]

If you have any they would be down close to the floor, you know, for the toes and to kick.

Look behind all those trim parts on the right side of your picture.

Another place to look is in the bath room.

No one can answer you questions with accurate answers unless you state your conversion type.

JIM