no power to Thermostat

[Bill n Rose]

Our less than 1 year old FC 19CB has a perplexing electrical problem. Yes it is under warrantee but we had reservations for the Smokies next week and have no ability to use heat.
We discovered the thermostat, the front fantastic fan and the TV booster do not have power. All else 12volt works, batteries good, fuses checked.
Any Ideas?

[uncle_bob]

Originally Posted by Bill n Rose

Our less than 1 year old FC 19CB has a perplexing electrical problem. Yes it is under warrantee but we had reservations for the Smokies next week and have no ability to use heat.
We discovered the thermostat, the front fantastic fan and the TV booster do not have power. All else 12volt works, batteries good, fuses checked.
Any Ideas?

Hi

If the fuses are all good (as checked with the ohms function on your multimeter) and you have voltage at the fuse sockets (as checked with the multimeter), then you have a loose wire. It's either a loose power wire or a loose ground. It could be multiples.

To check this, measure both sides of the power at each device. Check it to a convenient location on the skin of the trailer. If you get nothing on both sides, it's an open power wire. If you get +12 on both sides (with the device turned on) then you have an open ground. (If you get +12 on one and zip on the other, either the device is turned off or all is well ....)

Once you know which wire you are after, you can chase them down by looking here and there. Since they run behind the walls, this usually is a "tug tug .... did it move?" sort of thing with a helper doing one end and you doing the other.

My guess would be an open ground, but that's only a guess.

Bob

[Bill n Rose]

Thank you so much for your reply.
My husband is up on the roof with the AC unit and wants to know where the AC ground wire is. There is a hot pink wire secured to the frame of the AC housing with a black end . It plugs in where it says outdoor temp sensor. We thought that was the ground before we saw were it was plugged in.

I should also tell you that he " fixed it " temporarily a couple days ago when he was up there randomly giggling wires. We thought he was a genius.

We will let you know if we make progress.

[Bill n Rose]

Uncle Bob
We have checked found that the wire on the roof that my husband giggled to result in temp fix is the outdoor temperature sensor. He will climb up there later and get it to test it with the meter.
we will report back.
Thanks

[Al and Missy]

With multiple items not working, there is probably no power or a bad ground connection on a circuit which is fed by one of the fuses. Check the connections at the fuse panel for tightness. Check the nuts on the connections to the fuses and find the ground buss bars in your power center and check the screws that hold the wires in. Beyond that it may be a connector between wire harnesses between the walls.

Al

[A W Warn]

Originally Posted by Bill n Rose

Our less than 1 year old FC 19CB has a perplexing electrical problem. Yes it is under warrantee but we had reservations for the Smokies next week and have no ability to use heat.
We discovered the thermostat, the front fantastic fan and the TV booster do not have power. All else 12volt works, batteries good, fuses checked.
Any Ideas?

I suggest starting at the fuse panel and working outward on the circuit that is problematic. After confirming which circuit is the issue >
1. confirm fuse is good in that circuit
2. confirm the (+) wire is connected correctly to the fuse panel
3. go the first piece of equipment on the circuit and confirm that the (+) wires are connected properly
4. go to the second, third, fourth, etc... do the same.

Each piece of equipment is grounded directly to the trailer structure/skin. There is no common ground wire between them (at least that's the way it is on my trailers), so it is unlikely that all three items you mention have lost ground at the same time.

Good luck!!

[A W Warn]

Originally Posted by Bill n Rose

Uncle Bob
We have checked found that the wire on the roof that my husband giggled to result in temp fix is the outdoor temperature sensor. He will climb up there later and get it to test it with the meter.
we will report back.
Thanks

You mentioned the thermostat, the front fantastic fan and the TV booster have lost power. Jiggling the wires on the roof would have no affect on these.

Both the 120v and the 12v power supplies to the roof top AC unit comes from beneath the AC unit. On my trailers I have to check these by removing the interior cover. There is a yellow Romex NM cable supplying 120v power, with black supply wire, white neutral wire, and bare copper ground. Not sure about your trailer, but on mine there is a black/red wire providing 12 volt (+) power.

[Bill n Rose]

Thanks to all who are trying to help! We will be rechecking the fuses and connections. We will recheck the buss connections. So far all has tested good except not getting 12 volt to thermostat, antenna booster and front fan which are all on the same circuit as the AC.
As noted before, jiggling the outdoor temp sensor in the AC gave us a fix for several days but after the trip home the Jiggling doesnt do anything to fix the recurrence.
At this point we are no longer Giggling over the problem

[uncle_bob]

Hi

The wire you are giggling likely is moving another wire that's moving another wire .... Eventually it gets to the wire nut or broken wire or loose screw that is creating he problem. The only way to debug it is to follow through the circuit and figure out where the loose connection is. Since Airstreams are all a bit different, you will need to track things down as they apply to your specific trailer.

Bob

[guskmg]

I would tighten all electrical connections. It is amazing how many time several are missed and it is not just Airstream, but vender supplied components as well.
guskmg

[Bill n Rose]

Thanks for all the suggestions. We are still not able to get things going.
We went to the smokes last week doing without the furnace. 29 Degrees in am but glorious hiking weather and the elk were bugeling.
I made cinnamon rolls in am so we had a bit of heat from the oven.
Appt at out of doors mart Nov 5.
You cant be in a rush for warrantee work!
We will report back on the fix.

[FloydCoVa]

Did you camp in Catalochee to see elk?

[Bill n Rose]

You guessed it. If you're not squeamish about winding, steep gravel roads Cataloochee is a wonderful spot in the spring and fall.

[FloydCoVa]

Thank you for that info. Wwe trailered our horses there for a weekend long time ago. Might have to go back. Sorry for highjacking thread.

[AirstreamInc]

Originally Posted by Bill n Rose

Our less than 1 year old FC 19CB has a perplexing electrical problem. Yes it is under warrantee but we had reservations for the Smokies next week and have no ability to use heat.
We discovered the thermostat, the front fantastic fan and the TV booster do not have power. All else 12volt works, batteries good, fuses checked.
Any Ideas?

Hi Bill n Rose,*

We're very sorry to learn about the issue you are having. Please send us a direct message with your contact information and the last 6 digits of your VIN so we can share it with our Customer Service and Technical Support team. We look forward to helping you get this resolved.

You can also reach Airstream Customer Service and Technical Support at*customer_support@airstream.com*


Thank you.*

[Bill n Rose]

We are still looking at Nov 5 appt at Out of Doors Mart for warranty work including this problem with the thermostat.
Once again, Bill scrambled up on roof tried to push in all the plug in wires and rj-11 plugs on the AC to no effect but then he opened the furnace access and reset it and suddenly thermostat, front fan,heat and AC and TV booster all worked.
Interestingly we then turned the reset on the furnace off and the fan, thermostat and booster kept working.
At this point it is all working but we will see what the 3 hour drive to ODM does.
Also spoke with customer service at Airstream. They have been supportive but this is getting old for a new trailer!

[Bill n Rose]

Just wanted to let others know the problem remained resolved . The fix seems to have been all the tightening of connections in the AC and resetting furnace

What is still unexplained is the relationship between furnace reset, AC and thermostat, fan and booster power.

We have had a rocky first year but Airstream Support and ODM have been great.
Circuit boards on frig and water heater also had to be replaced along the way.
Also convertor went bad ....Fortunstely this is not our first rv .
Thanks for all the suggestions.

[BayouBiker]

12V goes up to the A/C - Heat Pump, there are splices there. Then it goes to the TV antenna where there are splices, then the fan. It was very likely one of the splice / wire nuts at the A/C - Heat Pump since all three devices were affected.

The Heat Pump logic board feeds power to the thermostat.

[Bill n Rose]

Thank you for that information. It is beginning to make sense. Do you have any idea about how the reset inside the furnace ties in?

[BayouBiker]

Originally Posted by Bill n Rose

Thank you for that information. It is beginning to make sense. Do you have any idea about how the reset inside the furnace ties in?

So a "feature" of the Dometic logic board in the heat pump along with the communication bus to the thermostat is that instrumentation, and communications are negatively impacted by the auxiliary connections including the temperature and freeze sensors, the furnace control wiring and furnace logic board. They can especially be sensitive to variances in neutral and high side voltages of each connected device. The system works well when everything is well grounded and well connected and operating correctly, but it is easily knocked out of wack.

So it is possible that resetting the furnace cleared an imbalance in the control system, caused the Dometic to also reset and precipitated a voltage surge in a loose connection in the power wires allowing it to make a better connection.

Okay, its a stretch but I don't have a better idea.....

And it's really not that outrageous. In my business connecting instrument and controls devices that are not specifically designed to be compatible causes no end of "weird" issues. Like I described above, everything is great when everything is new and tight, but different responses to averse conditions very often cause the devices to cause other attached devices to malfunction in weird and wonderful ways.