2002 U320 has no dash heat. I haven't tried to diagnose the problem because when traveling in cold weather we have had the Aquahot fired up.
My question is whether there is a manual shut off somewhere in the heater loop. I looked in likely spots but didn't see one. Couldn't find anything in the manual.
On our propane Foretravels there was a shut off at the water heater to push more heat to the front instead of going through the water heater. We have no heat at the dash unless the front furnace is running with the Aquahot. It may be a bad heater valve something similar.
Thanks
Rick,
No, there is no manual valve in the dash heating system. When the A-H is on, is there heat coming from the dash vents? It sounds like a call to James Triana is in order.
On mine, the furnace dash heat is only working if the ignition key is off. When the ignition key is turned on the AH dash heat vents turn off. I just assumed that was the way it was suppose to work.
FWIW: (This may or may not be applicable to your situation) Anytime I have problems with any dash AC or heater system in any vehicle, I always suspect a possible vacuum leak, cracked vacuum hose, or problem with a vacuum operated valve or switch or air door actuator.
It's possible your electric vacuum pump has failed. If that happens on my coach all the heat goes to the defroster vents and none comes out through the floor vents or dash vents. My coach is an older model than yours so it may have changed over the years. The next most likely thing to check is the coolant level in your radiator. In a passenger car when you have no heat it's often a sign of a radiator leak and the coolant level is too low to reach the heater core, which is usually higher up than the radiator, so the coolant drains out of the heater first. The next most likely thing is that the cable has come off the valve near the heater core. You'd probably notice that the heat control lever moves a lot easier than normal if the cable had fallen off. I don't know if your model still uses a cable to open the valve or not. They may have changed it. Also consider the outside air temperature and the fact that the heater is about 30' or more away from the engine. It's possible the water is cold by the time it gets to the heater, which is why there's a boost pump on my coach. If your boost pump isn't working you may not get enough hot water to the front of the coach. You can probably hear the boost pump come on and feel the vibration in the back of the coach when you start the pump with the engine off. You'll probably have to turn the ignition switch on to get the pump to run, but don't start the engine or you won't be able to hear the pump. On my coach the pump is located below the engine on the driver's side mounted to the steel frame of the coach. You can feel the pump vibrating if you put your hand on it when it's running. If the pump isn't working it's likely to be the relay, which is located by the isolator board on my coach. It's the exact same relay used for everything else so you could take one from a less vital device temporarily. The pump does make a difference when you're trying to keep ice from forming on your windshield. I had an opportunity to test it recently unfortunately.
Rick, I doubt his will help but try. Surely this thing for something else
I my bay where the manifold is, there is a brass valve like a hose bib valve. I recall MOT at sale saying that is for transferring more heat. I have not used it, just left well enough alone since things seemed ok until got so cold.
I will ask MOT tomorrow, but I think that valve MAY have impacted dash heat.
mike
Mike,
Are you referring to the valve that closes off coolant flow from engine to the water heater?
Excellent suggestion. When closed, that valve sends ALL the hot coolant from the engine to the dash heater rather than allowing it to "short circuit" through the water heater.
Brett
Now where is that valve on a 280?
Under the cabinet near the stove?
No heater hoses in the manifold bay. There are red and black heater hoses going into the bottom front of the Aquahot but the go behind the unit and there are no valves. I see the red heater hose exiting the engine block but no valve there. There is a heater hose visible in the gen compartment but no manual valve there that I saw.
The only heat at the dash is when it is directed through the defroster which also passes through the Aquahot heat exchanger if I understand correctly.
While writing this post I went back to the generator compartment and looked closer than I was willing to when the weather was so cold.
The heater valve appears to be controlled by a little step motor that allows it to bypass or forces the hot water to the heater core. I couldn't see any power going to it and finally found a plug hanging down looking a little forlorn. I plugged it back in so the next time the Cummins is heated up I will know if the problem is solved.
It came from Abilene and may have not been used in cold weather.
As always I appreciate the suggestions.
Hi Rick-
Have been watching this thread for a while and was hoping that Rudy or Roger B might see it and respond. Both are Aquahot trained techs. Roger B being the guru. Roger has a website @ RV Hydronic Heater Repair - Home (http://www.rvhydronicheaterrepair.com/) Roger's website also has an active membership and you might find your answer there. I would direct this question to them/him. Rudy is a great tech located in the Houston area and has serviced my unit. Both have been very helpful to many fofum members and am sure if you contact them they will provide some suggestions. Rudy, a commercial member, is an active member of this forum and you can do a Member Search for him and send him a PM.
When your Aquahot is on does any air come out of your defroster vents, kitchen vents or under the cabinet in the living area? Do the Bath and bedroom zones work?
Good luck.
Scott
Yes, Aquahot all works perfectly (other than the air noise.)
I think finding that heater valve unplugged will solve my problem.
If I could figure a way to slow the Aquahot fans it would solve the noise problem in the front and also keep it from cycling so often. I ordered one of those motor controllers but the later posts indicate it won't work on that motor. I might try the suggestion to put an off-on switch on the front Aquahot blower motor and see if it helps.
Thanks. I look forward to the day we meet in person.
So. The air is blowing out of the front vents, is hot but is too loud? Mine is loud too.
If, indeed, you only get air (hot or cold) from the defrost vents, you likely have a problem with the vacuum system. The default position if vacuum is not present is the defroster, NOT the heat or dash vents.
Brett
It switches between the vents fine. Just got cold air except for the defroster which is tied to the aquahot heat exchanger. I think finding that valve motor unplugged in the heater hose will solve my problem. That part of the coach isn't much different than any automotive application.