Dash Heater

nma33 · 11-17-2015, 10:13 AM

Our dash heater in the 35UN is not as hot as it should be, seems like when we drive the air coming out is warm but not as hot as in our other cars and SUV. Does anyone else have this issue? Any suggestions on what this could be. I will be taking it for service shortly and would appreciate any advice as to what the lack of heat could be.
Thanks!

hoppers4 · 11-17-2015, 12:23 PM

The only thing I know of that would affect the heater temp would be if your engine thermostat is defective. If it opens too soon your engine won't run in the proper temp range and this will eventually be detrimental to the engine.

bedrck46 · 11-17-2015, 12:53 PM

Suggest that you get a OBDll Bluetooth adaptor and the torque pro program for your smart phone Cost under $25.00 for both Then you cam monitor your engine temp and other functions. Also check your heater hoses into and out of the heater core. They should be hot and also check you radiator hoses for temp should be very hot also.

gmapatime · 11-17-2015, 01:08 PM

My experience with the Ford MH heater is that you will never get the same amount of heat, or at least think so, as you do your auto's. You need to remember that your autos have a much larger volume of air flow compared to area space being heated than the MH. Also, at least on out 31UL, the air vents are kinda on the small size being 2" dia.

We had ours on the other day when we started traveling and it took about 15 minutes to start feeling any change in temps. My biggest complaint with cold weather travels is the defroster, but that's another subject.

Steve

nma33 · 11-17-2015, 01:13 PM

Yea we have the 2" vents too, but our trip was 8 hours or so driving, and the heater never got hot, the only time it seemed somewhat hot was when we were stopped for a few minutes then the warm air turned hotter. But all in all it was warm at best.

On a good note we got north of 9.5mpg on the trip. the motorhome was empty but I though that was fairly good.

mowdoc · 11-18-2015, 08:00 AM

Our 35UN will blow warm air, warm enough you have to turn it back after while. It is not even close to as hot as regular cars and trucks though.

I would stick a thermometer in the vent and see what temp air is coming out. Perhaps a few of us could do same thing and report back. I will this weekend. Then we would have a baseline to compare with.

I'm pretty sure the heater will put out hotter air when underway. At idle the water pump on engine is not spinning as fast and the engine is not making a lot of heat. When underway the RPM is much higher and the engine is working hard. Work equals heat.

nma33 · 11-18-2015, 08:35 AM

It seemed hottest when we got on our way after spending the night in a hotel, about 3-5 minutes after starting up, before I started to drive, the vents were blowing hot air, as soon as we started driving it went back to warm air like the previous day. the good news is that we don't drive when it's too cold.

We are going to head down to VA in a couple of weeks so I will put a thermometer in the vent and see what we have. Great idea!

Thanks for the replies.

gmapatime · 11-18-2015, 09:03 AM

I'll do likewise this weekend as we head out and get back to y'all

Steve

D&MAKAFUN · 11-18-2015, 12:34 PM

We have had the dealer check with a thermometer twice. Like Steve said, you will never get the same amount of dash heat you do from your cars.
The key to having cabin heat is: prior to leaving, turn on your house furnace and let it run until the interior is toasty. The dash heat will normally keep the cockpit comfortable after that. Dash heat does not have the capacity to heat the house.
Worse case in really cold weather.......run the house furnace going down the road.

There has been a thread lately on the Precept Owners Group, join us...you'll find a lot of great info.

Scoutr2 · 11-18-2015, 12:40 PM

If you are getting warmer air through the floor vents, the problem is not the thermostat. I would think maybe the air directional door might not be operating properly and you are getting too much cold air mixed in with the hot.

mowdoc · 11-22-2015, 05:35 PM

Here are the results of my heater output test.

Ambient outside temp was 61f when test began and 68f at finish. The dash heater setting was on "vent" position during entire test and "temp" control was at full hot position. Fan speed was 2nd speed or 3rd speed, however fan speed had no impact on output temp during my test. All temps were measured with an Extech model 430 multimeter with temp probe connected. All temps were measured inside the dash vent opening located under left side of radio in a 2015 Precept 35UN coach.

During the test dash output varied between 126f and 134f degrees. Generally, the temp was coming out of dash vent at 130f under most conditions. It spiked up to 134 during a long hill climb in 3rd gear at 3600 RPM sustained for 3 minutes. The temp dropped to 126f during the decent of same hill (coasting).

I did find it interesting that the dash output rose to 132 during engine idle while parking the coach at end of test period.

In a nutshell, dash heater output while moving is 130f degrees in my coach but will vary 4f degrees when climbing hills or coasting down.

D&MAKAFUN · 11-22-2015, 05:49 PM

Nice mowdoc. very scientific. Thank you. I wonder what the temp difference is between exiting the dash/defroster and 1', 5' etc. Your test determined the heater/defroster's output is doing it's job but the system installed seems to run short of providing enough heat to keep the cockpit/occupants comfortable.

gmapatime · 11-23-2015, 07:38 AM

Although not as scientific as "mowdoc", I did take a reading from the heater this weekend. Probe was in bottom left vent under radio. Setting was on full vent, 2nd. speed with full heat mode. Our outside temp was 52 degs. I had a reading of 129 degs. after a twenty minute warm-up period. Travel was on flat roads.

Steve

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