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Old 11-23-2020, 12:34 PM   #1
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National RV Owners Club
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Dash heat

Tony discovered this morning that the dash heater isn't working for some reason. Is there some sort of valve or something somewhere for this? I'm not real clear on what he wants me to ask here but just wondering if anyone has any information that may help. The dash air works great, just no heat. It's a 2004 Dolphin 5342.

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Old 11-23-2020, 01:10 PM   #2
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Location: Powell River, B.C.
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Welcome to iRV2, Brenda

Yes there is a coolant valve in the dash heat/ air conditioning system .

Depending on the dash unit supplier , that valve can be cable controlled or electronic .
AND and this is the BIG AND, there is a possibility that a previous owner added manual valves to aid air conditioning operation.

So questions .
Has the dash heater ever worked since you've owned the coach ; or is this your first time trying the heater ?
Do you see any name on the heater system ?
Evans is common . as per pictures below showing the name and an electronic control valve.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
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Old 11-23-2020, 01:50 PM   #3
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Yes, it's the first time we have tried the heat. We purchased it during summer months so didn't turn it on. Previous owner said everything worked so just didn't check it. Tony was just looking at it, and it IS an Evans. It looks like there are no hoses hooked to the heater core, making me think that it was bypassed for some reason, perhaps there was a leak and previous owner did that instead of fixing it.
UPDATE: Just got in touch with previous owner..he said 10+ years ago during some AC work, it was bypassed. He doesn't remember why. He said they have used the generator and the heat pump since then.

Tony said maybe he should hook hoses to it to see if the heater core works. I'm sure he will try to find out the cost of replacing it just in case.
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Old 11-23-2020, 02:46 PM   #4
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Yes if you're needing heat , that would be the first step , and circulating coolant through the heater core and checking for leaks will give you an idea of the potential cost of repair .
Hopefully the by-pass was done to remove a leaking coolant control valve from the system . Replacing the control valve , although not cheap , is way less work than a heater core.
The picture , I posted , was of my original control valve , and the white residue visible was from the valve leaking. Due to my system's age the valve was obsolete and re-wiring the replacement to the control head was required.
Has Tony spotted any evidence of a wiring connector or cable for the valve control ?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
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Old 11-23-2020, 02:53 PM   #5
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I would pressurize it with AIR first. 10 PSI or so, You don't want to discover that the heater core leaks by having coolant pour out in the coach.

You could even do this by sealing off one fitting to the heater core and attaching a line to the other fitting and use and air nozzle to pressurize. If you can't pressurize it, there is a leak.
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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Old 11-24-2020, 03:54 PM   #6
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The house furnace will run off of 12v battery. No need to run the generator just for the furnace.
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Old 11-24-2020, 10:49 PM   #7
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The Evans electronic valves are known for sticking in the open position, in which case they mix hot air in with the cool a/c air. For this reason they sometimes get bypassed in the summer months. Some folks insert a manual shut-off valve ($20 at NAPA) to accomplish this, but perhaps your previous owner simply disconnected the hoses?

Here's a previous thread with some photos of the shut-off valve mod. I did this mod myself a couple months ago and it really helped the a/c blow colder.

2004 National Dolphin LX 6320, W-22, 8.1, Allison 1000, Front/rear Trac Bars, Hellwig Rear Anti-sway Bar, Sumo Springs, Roadmaster Reflex Steering Stabilizer, 2005 PT Cruiser Toad
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Old 11-26-2020, 12:17 PM   #8
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Look at the link that camJam posted above. See the 3rd pic.. If you have this valve, just open it and you will get heat then.
2004 National RV Sea Breeze 8341 35'
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Old 11-26-2020, 12:32 PM   #9
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Check out this link, on this forum, concerning the leaking of hot engine water into the ac-system.
Don and Marilynn
'04 Newmar Dutch Star 4010
Spartan Chassis/Cummins ISL 400
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