Loss of Power when Furnace Blower Shuts Down??? Help!!!

We are having to use our furnace....seems fine...gets going, heats, heat shuts off and blower continues for a bit. It seems that this is happening when our blower shuts down....we lose power. Everything but the coffee pot, microwave and TV has no power. It stays off for a few minutes, then comes back on. When it does come back, some of (or all of) our touch lights come on...waking us in the middle of the night last night....and it's still happening tonight. Any ideas? We are hooked to a 50 amp with surge protector

What it sounds like to me is that the furnace is pulling the batteries down dead, and then everything shuts off. But if you are plugged into shore power, all your 12V systems should be powered by the converter.

but they show full with that battery disconnect turned on so we still may just need to unplug the whole camper?

...

We just cut power to the whole camper and checked batteries and they showed 1/3 and that quickly went away, too. So...changing those today.

Here's the thing - if your rig is plugged into shore power, even with bad batteries you will show 100% on the internal battery charge display. That's because your converter is putting out 12V from shore power. But I don't know why your power is going out if you're plugged into shore power.

The fact that you disconnected from shore power and your batteries dropped down to 1/3 and died tells me that your batteries are dead.

Most converters charge the batteries, so I'm surprised your batteries are not getting charged. How long have you been plugged into shore power?

In any case, even if you remove the batteries entirely if you are plugged into shore power your 12V systems should be powered by the converter. There may be some systems that won't function if you remove the batteries but I'm not sure about that. I think the converter should power 12V systems (via 120V) even if there are no batteries or if they are dead.

Steve

You need to tell use what system goes on and off 12 volts or 120 volts. The word POWER and EVERYTHING does not help us. You have 2 POWER systems. Are the touch lights 120 volt lamps? If so unplug and put aside until the problem is fixed to stop confusion. So far all I can determine is you have a loose connection somewhere. Without proper information I can't help you. If the Surge protector says it ok then remove it for testing purposes. If it is an EMS and you have a low voltage problem then it is turning off the 120 volt power until it comes back into the 108 to 132 volt range. The lights will explane this for you. Look at the directions for uses. As a Master Electrician I would love to help.

When the furnace fan stops the 12v voltage does a bounce back. Now the 12v things won't work, but then they do. Does the 12v bounce back too high (how could that be--is there a setting on the ? set wrong?) and trip something (inverter?) then the battery (getting low) takes over? Now 12v voltage lower so inverter works again? They are on shore power. No idea what the converter is really doing. All very mysterious.

Yeah.....everything. The TV stays on, but no power for antenna? Sorry....I dont know a lot about it...but it seems that the outlets stay on...and everything else just quits working....and it's only for a few minutes...then everything powers back up. But, when it powers back up, it turns on some of the touch lights...or all...or none...and that part might be what caused a lot of the confusion when I originally posted... I just thought that might be a clue for someone who knows a lot more about it than I do. ;)

ArkansasWeekenders wrote:
We are having to use our furnace....seems fine...gets going, heats, heat shuts off and blower continues for a bit. It seems that this is happening when our blower shuts down....we lose power. Everything but the coffee pot, microwave and TV has no power. It stays off for a few minutes, then comes back on. When it does come back, some of (or all of) our touch lights come on...waking us in the middle of the night last night....and it's still happening tonight. Any ideas? We are hooked to a 50 amp with surge protector.

Addendum: I made that long post, then realized I mis-read the original post. :S

That's all normal for a furnace, and doesn't really sound like a converter issue. To clarify, when you say lose all power (assuming DC power) is that all lights, water pump, etc? If so, something is odd and you will likely need a multi-meter to figure it out. If it's just the touch lights it sounds like they are just triggering when relays trigger in the furnace.

Okay, so I'm going to try and explain things. Sorry if I over-explain, but judging from your comment of not knowing what the battery disconnect switch does I am assuming you know almost nothing about your RV power system.

Most RVs are designed to be able to work with or without shore power. Because of this, in general, the water pump, lights, vent fans, and furnace blower run on 12 VDC (the tongue jack and slides also run on 12 VDC). The fridge, if it's an absorption fridge, can use 12 VDC to light a propane flame which cools the fridge, or it can use 120 VAC if you have shore power to save propane. The water heater is usually similar. Wall outlets, microwave, TV, AC, etc all use 120 VAC. What this boils down to is that by using batteries, run everything in the camper except TV/AC/wall outlets, allowing you to use most electric systems from batteries while camping at sites with no electric. We do this quite often.

Now, this means you have two separate electric systems on board. One is 12 VDC, the other is 120 VAC. Your coffee pot, microwave, TV, and fireplace all run off 120 VAC, whereas your lights and furnace run off 12 VDC. So if your furnace is shutting down and lights are going out but NOT the TV, coffee pot, and microwave, then you have a problem with the 12 VDC system, and not your 120 VAC system. Got it?

Okay, so the 12 VDC system. This consists of a battery (or batteries), a fused distribution block, a 120 VAC to 12 VDC converter (what I think is bad), a battery disconnect switch and your DC loads, such as your furnace and lights. The battery only powers the furnace and lights IF you don't have shore power. If you have shore power, then the converter steps in, taking the 120 VAC shore power and converting it down to 12 VDC. Think of it like an oversized phone or laptop charger. When the converter is powered, the battery no longer has to power the loads, and in fact the converter will charge a dead battery in addition to running your lights and furnace.

Batteries don't like sitting around at much less than a full charge for long periods, they will sulfate and be permanently ruined. Because things in your camper will always use some 12 VDC power even when shut off (shut as your audio system), this means if your camper sits the battery will get drained, eventually (or quickly) ruining it. That's the purpose of the battery disconnect switch. It separates the loads in your camper from the battery, keeping it from discharging when your not using your camper. In normal operation, you should turn off the battery disconnect when you park your camper for storage if you don't leave it plugged in, and turn on the battery disconnect when you hook up to tow your camper.

So, long explanations done, let's dig in and give you a few things to test. I believe your converter is either not powered on or not working. Hopefully these tests figure that out and get you on your way, or let you know what you'll need to have fixed.

Battery Disconnect: If this is on (battery indicators show "full"), does the furnace and lights still cycle? Sounds like it does, but I just want to check. This should be on when camping, off when not camping if the camper isn't plugged in.

Power: Does the converter have power? Check your circuit breaker panel. Usually the converter is on its own breaker and labeled as such. Be sure the breaker is on and not off or tripped. Try flipping the breaker off and then on again.

Output: If you have a multi-meter (sounds like you're camping so you probably don't), you'll want to measure the converter output. There's usually large metal blocks near the automotive fuses in the DC side of your distribution panel. One will have a really thick red wire, the other a really thick white wire. Measure the DC voltage between these blocks. It should be 13.6 volts or so (up to 14.4) if your converter is running. Anything 12 or below and the converter is bad.

Fuses: The converter can't power any loads or charge the battery if the output fuses are blown. These are often multiple fuses parallel, right next to each other. They are the biggest fuses in there. I have two 40 A fuses. Pull these fuses and make sure they are not blown.

OP states "everything but coffee, TV, microwave loses power".

Just saw this post and read through the comments above. This is a new one for me. My first reaction was, what does the battery 12 volt system have to do with the AC 120 volt system? The common junction point is the converter (breaker panel).

The battery kill switch will shut the battery off. But if you are still plugged into shore power, the battery is now in a disconnect mode (same as disconnecting it) and all your house lights are now running through the converter's 12 volt DC output. House lights are 12 volt DC as is the furnace.

For anything AC powered, like the microwave, the common point of contact is the converter.

If the house lights are turned off, I don't understand how they can flip on all by themselves. But, this is what you are experiencing.

Easy test. Flip the battery kill switch. Unplug shore power. Everything should be powered off. Check everything. If you have an inverter, flip the kill switch to it also. On my 5er, the inverter is wired separate, on it's own kill switch and fuse system, directly to the battery. I does not have any dependency on the "converter". Everything off? Double check every plug and every light.

Now flip house battery on (leave "inverter") off. Turn on furnace (battery only), and let it cycle. Do house lights (12 volt battery) come on? If so, the common junction is the converter. If not, do just the opposite.

Kill the battery (disconnect or kill switch). Plug into shore power now. Converter will power your 12 volt system and your 120 volt AC system. Turn furnace back on. When it shuts off, do house lights come on? If so, the common junction point is the converter (breaker panel).

One more test. Unplug from shore power. Kill switch or unhook battery. But turn on and power up the inverter. What systems are now running? House lights and microwave? or just the refrigerator? Does the furnace run with just the inverter turned on.

Why do the three separate power feeds? To eliminate the inverter that's it back-feeding somehow into the converter, probably through the transfer switch that toggles the power outlet from the inverter, switching power from Shore power (AC 120) and the inverted battery to (AC 120), which is now powering the Converter (breaker box).

This will eliminate or confirm the problem is with your inverter. Anything, it's something to think about.

ArkansasWeekenders wrote:
We just cut power to the whole camper and checked batteries and they showed 1/3 and that quickly went away, too. So...changing those today.

Hold up, don't buy batteries yet. Sounds like your converter is bad, not your batteries. I just got up and I'm on my phone. Let me make some coffee and go to my desktop computer and I'll explain why I think this.

In the meantime if you have a multi-meter that can measure DC go dig that up.

ArkansasWeekenders wrote:
We just cut power to the whole camper and checked batteries and they showed 1/3 and that quickly went away, too. So...changing those today.

Bad batteries or not being charged. Have the batteries load checked at a auto store. Idiot lights ONLY use is to sell the rig - as in a great battery monitor is included which it is not.

Buy a $10 digital voltmeter and learn how to use it.