All lights on for 3 minutes off for about 30, then back on and so on

[AirSRepair]

Hi, I am trying to troubleshoot intermittent lights on/off -- afriend is living in a 73-74 airstream and her lights turn on and then go out after about 3 minutes -- then after 20-30 they come on for about 3 minutes and go off -- I am thinking either a loose connection or a thermal fuse issue -- however I have not worked on these buggers before --
Any ideas ?? Thanks

[uncle_bob]

Hi

Inside lights, outside lights, running lights, head lights? I'm guessing inside lights.

All the lights or just some of them? Knowing this would help narrow things down.

All the lights and the other 12V stuff? That would narrow things down a bit.

Motor home or trailer? I'm guessing motor home.

In motion only or also on shore power? This also would help a bit.

If this is running down the road and the headlights are going from full on to full off, I'd bet on a loose wire. If they are going from dim to bright, I'd bet on a fan belt. Inside lights "flashing" depends a bit on the MH / trailer thing. Thermal fuses are rarely in those circuits.

Probably best to get a bit more info before digging deeper with the guesses.

Bob

[AirSRepair]

Hi bob,
Thanks and sorry for such a lack of info -- this is a parked trailer and on shore power --
The lights I am referring to are the interior ceiling lights and bath light.. I walked in and turned on a ceiling fixture and it came on -- 3 position round switch ceiling fixture -- all other lights will come on also and then after they are on for 3 minutes roughly they go out -all of them - then after awhile they come on again for three minutes then off -- so that's why I'm thinking thermal fuses -- there is a panel under stove that has a lot going on - I see a fan (maybe converter ) -- then I mm pretty sure I found the wire that is supplying the power to lights -- an old terminal block -- yellow wire which was in ceiling of fixture I was looking into

I'll try and get a pic -- but may take awhile like tonight

[Rich W]

Bob probably has a better handle on this, but I would venture a guess that the converter is going bad and overheating, then shutting down until it cools off, then goes back on again. Like you said, probably some internal overload protection shutting it down.

You said you saw a fan, was it moving or just stuck? Maybe the cooling fan has gone bad. If there's room, see if you can add a small fan to improve the air flow into the converter. Even if it shuts down again, if the pattern improves then I would say the fan is the problem, possibly blocked with dust and dirt.

[OTRA15]

Older AS have 12-volt circuit breakers which reset automatically I believe. There may be a problem with the wiring or one (or more) of the lights.

https://www.google.com/search?q=12+v...=airforums.com

The first few threads look hopeful IMO. There was a thread about a year ago, with exactly the same problem in an older AS, but I can't find it right now.

Is there an owner's manual for the trailer? It will help locate the 12-volt breaker panel, and a close exam of this panel will likely [IMO] indicate that the breakers cannot be turned on and off manually.

If your friend does not have an owner's manual, we can locate one online. Please advise.

Good luck!

Peter

PS -- Maybe this is the thread:

http://www.airforums.com/forums/f449...es-167084.html

[Dan@LED4RV]

Originally Posted by OTRA15

Older AS have 12-volt circuit breakers which reset automatically I believe. There may be a problem with the wiring or one (or more) of the lights.

https://www.google.com/search?q=12+v...=airforums.com

The first few threads look hopeful IMO. There was a thread about a year ago, with exactly the same problem in an older AS, but I can't find it right now.

Is there an owner's manual for the trailer? It will help locate the 12-volt breaker panel, and a close exam of this panel will likely [IMO] indicate that the breakers cannot be turned on and off manually.

If your friend does not have an owner's manual, we can locate one online. Please advise.

Good luck!

Peter

PS -- Maybe this is the thread:

http://www.airforums.com/forums/f449...es-167084.html

I think Peter is right-on here. The breaker is a bi-metal switch which is suppose to pop or disconnect when there is a problem. The breaker is doing its job or is weak. I think they are behind the sofa. It is either a 15 or 20 amp. If you replace it and the problem stops it was weak. If you replace and still the light blinks you have a overloaded circuit or a short. There is a buss of wires that run down the ceiling, off to the side, on the door side. I would try to guess the farthest point on this circuit and disconnect that item. Then see if this fixes the problem. If so, the short is there. If not, move to the next item/light and disconnect. Keep going until you find the problem.

[kdickinson]

This happened to us also and I agree it is likely the converter. For us that was the failed component and a quick replacement fixed the problem.

[Boxite]

Self-resetting circuit-breakers will behave as described... and one way this can occur is when someone replaces a light-bulb (usually incandescent but even LED can do this if it's internally shorted)... and they use the wrong lamp. For example, replacing a GE 1142 with a GE 1157 (or something similar.) The 1157 will draw so much more wattage the circuit breaker is resetting itself. That is only a suggestion... not a diagnosis of this problem. Hope it helps.

[ijustlee]

It would also help to know how many light fixtures you are running at the same time. If just 2 bulbs on the low setting of one fixture does it cycle? A 6 bulb fixture pulls about 10 amps to light all the bulbs and trying to run too many fixtures at the same time can overload a small converter. Something is cycling to protect itself or the wires due to load and may not be broken, just not understood. My guess would be converter is overloaded but more info is needed.

[HowieE]

The first thing you have to do is determine where the open is happening. Find the breakers in your trailer and measure the voltage on the input side after the lights have gone off. If you have power there while the lights are off it is the breaker or a short beyond the breaker. Not likely a short as that would blow the breaker as soon as you turned the lights on. If you do not have power on the input side of the breaker check for voltage on the batteries. If the batteries are dead check the output of the convertor. If there is no voltage on the output of the convertor and the batteries are dead. Disconnect the batteries and once the convertor resets see if the convertor alone will power the lights. if so the combined load of dead batteries and the lights is tripping the internal overload in the convertor.

You can't do anything till you no where you are losing power.

[Boxite]

I'm tempted to suggest:
Individually turn one of the light fixtures off...to see how many will be supported continuously... or to isolate the one drawing too much.

[AirSRepair]

Thanks for responses, Been busy working but appreciate everyones thoughts so far >> i will look into all and start chasing down the problem

[HowieE]

Originally Posted by Boxite

I'm tempted to suggest:
Individually turn one of the light fixtures off...to see how many will be supported continuously... or to isolate the one drawing too much.

You are describing the reciprocal of the test for a short, turning lights on one a time is that test. However a short would trip the breaker as soon as the lights were turned on not after 3 minutes.

[HiJoeSilver]

If it was an AC circuit breaker yes. It's a 12v fuse, and likely/unfortunately one of the auto resetting 12v bimetallic fuse/circuit breakers. They can take time to heat up enough to get them to open then takes time to cool down. It depends on how direct the short is. A glass or ATM fuse would blow quicker and stays that way.

The description leads more to a slight overload rather than a direct short though. So hopefully that's good news. A multimeter can make the troubleshooting process go much faster.

if the converter were doing this the battery would try to keep 12v going. Do any other 12v items (try water pump as ceiling fans are usually on same circuit as lights, the bath fan is usually on a different circuit) work when the lights go out. This can quickly rule in or out a converter problem.