Nobody at the office can reset your thermostat

The air conditioner stops at half past one on a closed rig in July. The thermometer inside will not have anything to say about it for another twenty minutes, and by the time it does, the question is no longer whether something is wrong. It is who you are telephoning: the campground office, or the person who has your spare key.

Those are the only two answers, and they are decided by one thing — whether the pedestal is still delivering power. If it is not, the office can very often fix it in five minutes with a breaker. If it is, then the fault is inside your rig, and no amount of phoning anybody will reset a thermostat or a tripped air-conditioner breaker. Somebody has to open the door.

Which makes this the same article as the furnace one with the seasons swapped, and the same trap: the temperature reading is the one everybody sets, and it is the last to know.

The head start comes from the pedestal

a. The shore power monitor going dark

A Power Watchdog runs off the line it measures, so a dead pedestal takes it off the air with it. Polling every 30 seconds, allowing a couple of missed polls before calling it, that is an alert leaving inside a minute or two — well before the rig has warmed by a single degree. Alert on it going offline, on voltage below roughly 104 volts, and on any non-zero error code. A rooftop unit is at risk under about 104 anyway, so that threshold is earning its keep twice.

The false positives are all things you did: unplugging to move sites, the pedestal breaker off while you swap cords, a brief reconnect. None of them lasts, and none of them coincides with a hot rig unless you left somebody inside it. The real blind spot is the opposite case — if the air conditioner’s own breaker tripped, or the thermostat died, or the coil froze, the Watchdog goes on reporting a perfectly healthy 120 volts and knows nothing at all about it.

b. The current the compressor is not drawing

The same device answers the opposite question. A rig with a rooftop compressor running draws roughly 12 to 16 amps; if the current sits under about 3 amps through an afternoon that should have it cycling, the compressor is not running, whatever the voltage says.

It also reads the whole rig rather than the air conditioner, so a water heater element at around 12 amps, or the converter refilling a drained bank, can hide an idle compressor completely. It tells you something is drawing. It cannot tell you what.

When the power is fine and the A/C still is not

c. The soft starter’s two counters

If the air conditioner has a Micro-Air EasyStart, it keeps two numbers that separate the two failures people otherwise confuse. A fault count that has gone up since this morning means the compressor tried and the soft starter faulted it. A start count that has not moved across an afternoon that should have cycled means the compressor was never asked to run at all — a thermostat off, the wrong mode, or its breaker.

Those are different problems with different fixes, and no other reading in the catalog tells them apart. Two limits: alerting on a counter increment is not a rule shape available today, so treat these as the history you read when a heat warning lands. And the module answers the hub only while the air conditioner has power, so an EasyStart that goes unreachable between cycles is behaving exactly as designed — never build an alert on its silence. The decode behind those counters came from the community rather than from our bench, which we say out loud.

d. The shunt, if the A/C runs off an inverter

On hookups a SmartShunt shows a small positive current, because the converter is topping the bank up. Current going below about minus 5 amps on a day you expect to be plugged in means the converter stopped, which means shore power stopped, which means the air conditioner stopped — the same news as the Watchdog, arriving from the DC side.

If you run the air conditioner from a large inverter it does something the Watchdog cannot: a draw below roughly minus 80 amps at 12 volts is the air conditioner now running on your batteries, and the counted battery percentage beside it is the clock on how long that lasts. Nothing decodes until the Instant Readout key from VictronConnect is saved against it in the hub, and it stays blind to a tripped A/C breaker for as long as shore power is up.

e. The temperature, arriving last

Warn above 82°F and go critical above 90 — examples, and the full argument about the number is on the pet safety page. A sensor reporting once or twice a minute is not what makes this slow. The rig’s own mass is: tens of minutes of it, and by the time the number moves your head start has been spent.

Set it anyway. Every other reading here can miss a cause; this one cannot, because it measures the consequence rather than a component. It also answers the question that actually matters, which is not whether the compressor is running but whether the rig is getting dangerous. Keep the sensor out of the sun and away from the fridge and the stove.

What would close the gap is the thermostat itself, and we cannot read one yet: the EasyTouch RV connects and has a driver, but its field mapping is unconfirmed and nothing decodes. Do not buy one for this.

The combinations

One reading opens the question and a second closes it, which is what the whole cookbook is built on.

• Watchdog offline or under 104 volts, temperature climbing — the pedestal, not your air conditioner. Ring the office first, then whoever holds a key.
• Watchdog healthy at 120 volts, current under 3 amps all afternoon, temperature climbing — shore power is fine and the A/C itself has failed: its breaker, the thermostat, a frozen coil. Nobody at the office can reset any of those.
• Fault count up, and the Watchdog was under about 108 volts at that minute — low campground voltage tripped the soft starter. It will retry after its short-cycle delay, and if the voltage stays down it will keep dropping out all afternoon. That is the brownout article.
• Start count flat, Watchdog current around 2 amps, temperature climbing — the compressor was never asked to run. Thermostat off, wrong mode, or the A/C breaker. Not an outage and not a compressor fault.
• Watchdog offline and the shunt discharging — shore is gone and the rig is on batteries. If the A/C is on the inverter, the battery percentage is now your countdown.
• Watchdog dropped and the hub went offline in the same minute — both were fed from the pedestal and both died with it, so nothing further is coming all afternoon. Move it to 12 volts; that is its own article.

What none of this tells you

Beyond power against not-power, none of it says why. A frozen coil, a failed capacitor, a thermostat that quietly stopped calling for cool — those look alike from every reading we have, and nothing here restarts anything.

What to do about it

The pedestal monitor first. It reads every 30 seconds, it fires before the temperature has moved at all, and the failure it catches is the one that starts most heat emergencies. Then a temperature sensor in the living area, because it catches everything the electrical side cannot see, late but reliably.

Add the soft starter’s counters if the air conditioner already has one — that is a history check rather than an alert, and it is what turns “the A/C stopped” into “the compressor faulted at ten past two”. Add the shunt only if you run the air conditioner from an inverter, where it stops being a diagnosis and becomes a countdown.

Where to get one

In the order above. Which Watchdog depends on your service; the sensor comparison covers which thermometer, and the soft start guide is the separate argument about installing a soft starter at all, since this article only uses one you already have. The compatibility database has the rest.