I'm in the spare tire compartment.............

[blacklab]

I'm looking forward in the spare tire compartment of my '95 Royale. There are blue hoses coming in from the rear and tie into the copper. This pump is turned on via the H20 switch on the dash. What does this do??

[VegasDogMan]

Looks like Hot water Recirc system normaly used for coach heat. I also see Hot Water Diaphragm Valve in lower right corner of picture.

Need Valve Open and Pump ON to heat coach when engine running.

[truk4u]

Lee is right, on my Marathon, the manual explained the pump brings hot coolant to the front for the dash heat/defrost. The coolant lines are so long they have a tendency to cool down by the time it gets to the front via the engine water pump. I also had a valve in the engine compartment down under the fan assembly that shut off all coolant flow to the front heater core for summer time operations. Be sure your valve is open before running the pump.

[blacklab]

Thanks. I'll make sure that the valve @ the engine is open. When I bought the coach, the seller mentioned something about this valve. It is a ball valve with a long wire rod on it for opening/closing 'cause it's buried on the port side down low. He said "don't touch it" The coach lived in Texas/California so I can see that they didn't need heat. Any idea about the blue on-off button that says "heat ex" ? I'm thinking that this may open the solenoid valve?

[Jerry Winchester]

I believe the "Heat Ex" button is for the AquaHot circulation pump that warms the engine from the diesel heater.

[blacklab]

I knew I'd hear from you Jerry!! Thanks. I'll look into the Aqua Hot system and see. It rained all weekend here in Mpls. so I had some time to crawl around the bus and try to figure out what buttons to push..............or not.