Signs Your RV Refrigerator Cooling Unit Is Failing
The three warning signs to check before you lose a fridge full of food on the road.
RV refrigerators run on absorption cooling — ammonia, water, and hydrogen sealed inside a boiler tube, driven by heat instead of a compressor. It's a simple, reliable system that can run for decades, but when it fails, it fails in a handful of predictable ways, and catching the early signs saves you from finding out the hard way on a trip.
The clearest warning sign is a yellowish, crystallized stain on the black cooling fins at the back of the refrigerator, visible from the exterior access panel. That's ammonia that has escaped the sealed system — once you see it, the cooling unit itself needs replacement, not a recharge or a simple part swap. A second sign is a refrigerator that cools fine while parked and level, but drifts warm once you're on the road; before assuming the cooling unit is failing, check that the fridge is actually level (absorption units need to sit close to level to circulate) and that the rear vents aren't blocked by stored items or a wasp nest, which is more common in Tucson than most owners expect.
The most urgent sign is a sharp, rotten-egg-like ammonia smell near the refrigerator vents, inside or outside the RV. That means the boiler tube has ruptured. If you smell it, turn the refrigerator off, ventilate the area, and get it looked at — ammonia fumes aren't something to keep running through.
Tucson's ambient summer heat makes all of this worse: a cooling unit that's marginal in a mild climate often fails outright once outside temperatures climb into the triple digits, since the unit has to reject heat into air that's already hot. If your RV sits in outdoor storage through the summer, a quick fridge check each spring — level, clean vents, no yellow staining — catches most problems before they become a spoiled-food emergency on the road.
RV Water Heater Won't Heat: What to Check Before You Call
A quick, safe checklist that solves a surprising number of no-hot-water calls without a service visit.
Before assuming an RV water heater needs a real repair, a few checks take five minutes and rule out the most common — and cheapest — causes. First: is the bypass valve set correctly? If the water heater was winterized or the bypass was switched for any reason, water can be routed around the tank entirely, meaning the heater lights and runs fine but no hot water ever actually reaches the faucet.
Second, on gas mode: is the propane tank actually full, and is the regulator supplying steady pressure? A water heater that won't stay lit is often blamed on the water heater itself when the real cause is a nearly-empty propane tank or a regulator issue affecting every gas appliance on the rig, not just the heater. Third, on electric mode: check that the breaker for the water heater's electric element hasn't tripped, and that shore power or the generator is actually supplying a full 120V — a low-voltage connection can run the heater weakly without heating properly.
If those check out and it's still not heating, the most common real faults are a failed thermocouple or sail switch (pilot lights, then won't stay lit), a bad thermostat or heating element (electric mode runs but water stays lukewarm), or a fouled burner orifice restricting gas flow. None of these require replacing the whole water heater — they're straightforward on-site repairs once diagnosed correctly.
The one sign that does point to full tank replacement: a steady leak or visible crack in the tank body itself, as opposed to a drip from a fitting or the pressure relief valve (which is often just normal pressure venting). Tucson's hard water also accelerates anode rod corrosion on tanks that have one — checking it once a season is cheap insurance against a surprise leak.
How Tucson Monsoon Season Puts RVs' Floors at Risk
Sudden downpours find every weak seam, seal, and blowout patch faster than steady rain ever would.
Tucson doesn't get much rain, but what falls during monsoon season (roughly June through September) tends to arrive fast and hard — heavy, wind-driven downpours rather than gentle, steady rain. That matters for RV floors and subfloors more than most owners realize, because wind-driven rain finds weak points that a light drizzle never would: a roof seam that's due for resealing, a slide-out seal that's compressed and cracked from years of Arizona sun, or — critically — a subfloor repair from an old tire blowout that was patched over the visible hole but never fully sealed underneath.
Once water gets past the exterior barrier, it doesn't evaporate quickly inside a closed-up RV, especially one sitting in outdoor storage between trips. That's how a small, unnoticed leak turns into a soft or spongy floor spot weeks later, often far from where the water actually got in — it travels along the subfloor before showing up as damage somewhere else entirely.
The practical takeaway before monsoon season each year: check roof seams and slide-out seals for cracking or gaps, and if your RV has ever had a tire blowout, don't assume the floor repair that followed is watertight unless it was specifically inspected and resealed for that. A subfloor that's structurally patched but not properly sealed against water is exactly the kind of weak point monsoon rain is good at finding.
If you already have a soft spot, discoloration, or a musty smell inside near an exterior wall after a storm, it's worth having it inspected before the next one — water damage that sits inside a closed subfloor cavity gets worse, not better, with time.
RV Battery Keeps Dying or Won't Hold a Charge? What to Check Before You Call
How to tell a bad battery from a charging problem, why Tucson heat and dry camping wear batteries out, and when to bring in a mobile tech.
A house battery that is flat by morning, or that will not hold a charge after a full day on the plug, is one of the most common problems RV owners run into in Southern Arizona. The tricky part is that the battery is not always the culprit. Sometimes it is worn out, but just as often something else is draining it, failing to charge it, or cooking it. Replacing a battery without finding out why it failed usually just repeats the problem a few months later, so it pays to sort out the cause first. Keep in mind that an RV battery can deliver a lot of current, so work calmly, take off rings and watches, and keep metal tools from touching both terminals at once.
Start with the heat, because Tucson is hard on batteries. Lead-acid batteries age faster the hotter they run, and a common rule of thumb is that sustained high temperatures can cut their life dramatically. A battery sitting in a closed compartment, a tongue box, or a storage lot in July can be far hotter than the air around it. Heat speeds up internal corrosion of the plates and, in flooded batteries, makes the water evaporate faster. If your batteries are the flooded type with removable caps, check the fluid level only after a full charge, wear eye protection and gloves, and top up with distilled water only. Never open or pry at a sealed battery. If the batteries are tucked in a hot spot, shade and airflow help more than most owners expect.
Dry camping, or boondocking, in the desert is the other big battery killer. Without hookups, everything runs off the batteries: the furnace fan, lights, water pump, fridge controls, and an inverter if you have one. The usual guidance for lead-acid is to avoid draining them below about half charge, because repeated deep discharges build up hard sulfate on the plates and permanently cut capacity. A resting voltage of roughly 12.7 volts is close to full, around 12.2 is about half, and anywhere near 12.0 is nearly empty. Those numbers only mean something after the battery has rested for a few hours with no loads and no charging. Solar helps a lot in Arizona sunshine, but only if the panels, the charge controller, and the wiring are all doing their part, and a battery that is already sulfated may not recover even with plenty of sun.
If the battery dies while the RV is parked, suspect a parasitic drain, which is something quietly pulling power when nothing seems to be on. Common sources include a propane or CO detector, a stereo or thermostat memory, the refrigerator control board, a tank monitor panel, and a relay or switch that is stuck on. Stored batteries also lose charge on their own, and they do it faster in heat. A simple, safe test is to flip the battery disconnect switch off before you park it for a week or two. If the battery holds its voltage with the disconnect off but is flat when it is on, something is drawing power. Tracing which circuit it is takes a meter and some patience, and that is a good job to hand to a technician. For a rig that sits in storage, a maintainer or a small solar panel with a proper controller keeps the battery topped up.
Next, look at the connections, because they cause more trouble than people expect. White or blue-green crust on the terminals, a loose cable clamp, or a corroded ground strap restricts current and can make a good battery act weak. Turn off the disconnect and unplug shore power first, then remove the negative cable before the positive. Clean the clamps and posts with a baking soda and water solution and a brush, keeping it out of the cell openings, then rinse, dry, and reconnect the positive first and the negative last. Wear eye protection and gloves. A charging lead-acid battery gives off hydrogen, which is flammable, so keep sparks, flames, and smoking well away and never disconnect a cable while a charger is running.
Then check the charging side. The converter/charger turns shore or generator power into 12-volt charging, and if it is weak, the battery never fills up no matter how long you stay plugged in. With the RV on shore power and the battery connected, a multimeter at the battery posts should read noticeably above the resting voltage, often somewhere around 13 to 14.5 volts depending on the charge stage. If it sits near 12 volts, check the converter's fuse or breaker and the battery disconnect before blaming the battery. If it stays well above 15 volts, or the battery gets hot or smells like rotten eggs, the charger may be overcharging, which can cook a battery in a matter of weeks. Converter fans that never run, or that never stop, are another hint the unit needs service. If you charge from the tow vehicle, a long thin wire on the trailer cord often delivers very little.
So how do you tell a bad battery from a charging problem? Charge the battery fully, disconnect it from the RV, and let it rest for several hours. If the resting voltage drops quickly or never gets near 12.6 volts, one or more cells are probably failing. If it reads fine at rest but lights dim, the pump slows, or the inverter alarms the moment you add a load, the battery is weak under load, which only a proper load test confirms. If the battery tests fine but the voltage never rises on shore power, look at the converter or the wiring. And if it charges and tests well but is flat after a week in storage, think parasitic drain. A swollen case, a hot battery, or a leak means stop charging it and replace it.
A quick word on battery types. Flooded lead-acid batteries are the cheapest but need water and ventilation. AGM batteries are sealed and more forgiving, though they still dislike heat and deep discharge. Lithium iron phosphate (LiFePO4) batteries are lighter, handle deeper discharges, and hold steady voltage, which also means voltage alone is a poor fuel gauge and a battery monitor helps. The catch is charging. Many older converters were built for lead-acid and may undercharge lithium or lack the protection it needs, so a lithium upgrade is a charging-system project, not just a battery swap. Do not mix old and new batteries, or different types, in the same bank.
Some situations call for a technician: a battery that dies again soon after being replaced, a converter that is not charging or is overcharging, melted or scorched wiring, a swollen or leaking case, a lithium system that will not charge, or a draw you cannot track down. When you call, have this ready: the battery type, number, and approximate age, the voltage readings you took, how long the charge lasts, how the RV is charged (shore power, solar, generator, or tow vehicle), and what you have already checked. It also helps to say where the RV is parked.
The good news is that you do not have to haul the RV anywhere. Big Sky Mobile RV Tech Services has served RV owners since 2006 and comes to your driveway, storage lot, or campsite, by appointment, Monday through Friday, 8:30 AM to 6:00 PM. For mobile RV repair in Tucson, Oro Valley, Marana, Sahuarita, Vail, Green Valley, and Catalina Foothills, call or text (520) 818-2310.
Quick answers
Usually one of two things: the battery has lost capacity from heat, age, or deep discharges, or something is drawing power while you sleep or while the RV is parked. A load test and a check for a parasitic draw tell the two apart.
Yes. High temperatures speed up plate corrosion and water loss in lead-acid batteries, and a hot compartment or storage lot can run well above the outside air. Shade, ventilation, and a charger that does not overcharge all help them last.
Not always. Lithium works best with a charger set for it, and an older lead-acid converter may undercharge it or lack protection. Check the converter, any inverter, and the wiring first, or have a technician confirm the setup before you buy.
Check the voltage at the battery posts while on shore power. Near 12 volts means it is not charging, which points to the converter, a fuse, or wiring. A normal charging voltage with a battery that still goes flat points to the battery itself or a draw.