# Problem With My Surburban Heater



## toocheap (Apr 5, 2010)

I need some help with my heater on my 28 rss outback.

It will come on for about 1 minute or 2 and then start going off and on. It pulsates down. The blower seems to be fine. The heat is good until it starts pulsating.

All the lights will dim when it does this pulsating down. I can't see where there is a "limiter switch" or anything else for that matter.

Anybody run into this problem before?

Thanks.


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## CamperAndy (Aug 26, 2004)

Sounds like a weak battery, the blower may sound good but it really has to move the air for the system to work. Try it with the trailer connected to shore power to see if it still dims the lights and cycles.


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## toocheap (Apr 5, 2010)

CamperAndy said:


> Sounds like a weak battery, the blower may sound good but it really has to move the air for the system to work. Try it with the trailer connected to shore power to see if it still dims the lights and cycles.


Hi.
Yes it is already hooked up to our house current. I think it has to do with an item called a "limit" switch that is shorting out or is defective but that is all the info i have on it. Thanks.


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## CamperAndy (Aug 26, 2004)

The over temp limit switch would not cause the lights to dim. Now the sail switch that is used to monitor air flow could give you the symptoms but again that fault typically comes back to be a low voltage issue.

If you are connected to shore power then you need to monitor the voltage at the converter, battery and heater when it is running. To see where you have voltage losses.


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## toocheap (Apr 5, 2010)

CamperAndy said:


> The over temp limit switch would not cause the lights to dim. Now the sail switch that is used to monitor air flow could give you the symptoms but again that fault typically comes back to be a low voltage issue.
> 
> If you are connected to shore power then you need to monitor the voltage at the converter, battery and heater when it is running. To see where you have voltage losses.


Thanks for your help.

I ran the A?C for about 10 min and it works fine.

The Heater still does the same thing.

Iam not sure how to check voltage for the heater. The battery was charged and is working ok although it did take a lot of water...


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## Nathan (Jan 2, 2007)

Try disconnecting the battery. If it is bad it will draw a lot of current and the converter won't necessarily be able to keep up. When you do disconnect it, just pull off the negative terminal (If the positive lead hits the frame you'll pop some circuits in the trailer).


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## CamperAndy (Aug 26, 2004)

toocheap said:


> Iam not sure how to check voltage for the heater. The battery was charged and is working ok although it did take a lot of water...


Needing to add a lot of makeup water is never a good sign. Disconnect the battery and try to run the heater with just the output from the converter as Nathan suggests.

Also get a volt meter the instruction that come with it will help you get started and we can help with specific locations to check.


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## toocheap (Apr 5, 2010)

Nathan said:


> Try disconnecting the battery. If it is bad it will draw a lot of current and the converter won't necessarily be able to keep up. When you do disconnect it, just pull off the negative terminal (If the positive lead hits the frame you'll pop some circuits in the trailer).


After doing the above the heater ran for about 3 min then started going in and out. After using the remote to shut it off - it was doing the same thing... almost like it was "cycling down?"

thanks for your suggestions.

JD


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## Lmbevard (Mar 18, 2006)

Sounds like the blower motor is bad. It overheats kicks out and then starts again when it cools enough. As far as checking voltage, stop at a Lowes or Home Depot (or even a Wal-Mart) and pick up a cheap digtal Voltmeter. Make sure it will read AC and DC. The easiest way to check the voltage is to set the Voltmeter to 600V AC and stick the probes in a wall socket. Should read 110-125V. Turn on the heater and watch the display. I bet when the heater starts dragging down, you'll see the voltage drop to about 50V. If this only happens when you run the heater, the best bet is that the blower motor needs replacing. 
Here's a place to get parts: http://www.pplmotorhomes.com/parts/rv-furnaces-suburban-atwood-parts-1.htm#Furnace Parts - Blower Motors
Here's Suburban's site: http://www.rvcomfort.com/suburban/service/repairs.php
I don't think that replacing the motor and limit switch would be that hard if you know what you're doing, but it might be safer to have someone that has worked on them before do it so if it blows us you have someone to sue. Just kidding.


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## CamperAndy (Aug 26, 2004)

Lmbevard said:


> Sounds like the blower motor is bad. It overheats kicks out and then starts again when it cools enough. As far as checking voltage, stop at a Lowes or Home Depot (or even a Wal-Mart) and pick up a cheap digtal Voltmeter. Make sure it will read AC and DC. The easiest way to check the voltage is to set the Voltmeter to 600V AC and stick the probes in a wall socket. Should read 110-125V. Turn on the heater and watch the display. I bet when the heater starts dragging down, you'll see the voltage drop to about 50V. If this only happens when you run the heater, the best bet is that the blower motor needs replacing.
> Here's a place to get parts: http://www.pplmotorhomes.com/parts/rv-furnaces-suburban-atwood-parts-1.htm#Furnace Parts - Blower Motors
> Here's Suburban's site: http://www.rvcomfort.com/suburban/service/repairs.php
> I don't think that replacing the motor and limit switch would be that hard if you know what you're doing, but it might be safer to have someone that has worked on them before do it so if it blows us you have someone to sue. Just kidding.


Remember the heater has a 12 vdc motor and it will not affect AC voltage unless the issue is with the converter. I would start with checking the voltage on the DC side at the converter output.


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## toocheap (Apr 5, 2010)

CamperAndy said:


> Sounds like the blower motor is bad. It overheats kicks out and then starts again when it cools enough. As far as checking voltage, stop at a Lowes or Home Depot (or even a Wal-Mart) and pick up a cheap digtal Voltmeter. Make sure it will read AC and DC. The easiest way to check the voltage is to set the Voltmeter to 600V AC and stick the probes in a wall socket. Should read 110-125V. Turn on the heater and watch the display. I bet when the heater starts dragging down, you'll see the voltage drop to about 50V. If this only happens when you run the heater, the best bet is that the blower motor needs replacing.
> Here's a place to get parts: http://www.pplmotorhomes.com/parts/rv-furnaces-suburban-atwood-parts-1.htm#Furnace Parts - Blower Motors
> Here's Suburban's site: http://www.rvcomfort.com/suburban/service/repairs.php
> I don't think that replacing the motor and limit switch would be that hard if you know what you're doing, but it might be safer to have someone that has worked on them before do it so if it blows us you have someone to sue. Just kidding.


Remember the heater has a 12 vdc motor and it will not affect AC voltage unless the issue is with the converter. I would start with checking the voltage on the DC side at the converter output.
[/quote]

Hooked up the VOM and the A/C stayed consistent throughout the test. It did start acting alittle different though. I made a video and will upload the youtube address.


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## CamperAndy (Aug 26, 2004)

If the AC volts were steady then you need to check the DC side from the converter when it is running.


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