RV Furnace & Heating Repair

Florida winters are mild, but 40-degree nights in an RV aren't

People who've never spent a winter in a Florida RV think they won't need a furnace. Then December rolls around. Jensen Beach sees nighttime lows in the mid-40s through January and February, and some nights dip into the high 30s. An RV with its thin walls and minimal insulation loses heat fast, and a space heater just doesn't cut it when the temperature drops below 45 outside.

The catch is that your furnace has been sitting idle since March. Seven to eight months of Florida heat, humidity, and insects take a toll. We get more furnace service calls in the first two weeks of November than the rest of the year combined, because that's when everyone turns on the heat for the first time and discovers it doesn't work.

Scott Marlins has been repairing RV furnaces in Jensen Beach for over 10 years. With 3,200+ total repairs across Martin County, he knows exactly what breaks, why it breaks, and how to fix it fast. Most furnace repairs take 1 to 2 hours on-site.

How RV furnaces work

Almost every RV uses a forced-air propane furnace. Here's the sequence that happens when you turn up the thermostat.

The thermostat sends a signal to the furnace control board. The board energizes the blower motor, which starts pushing air through the combustion chamber and duct system. After 15 to 30 seconds (enough time to purge any gas from the chamber), the sail switch detects airflow and signals the board to open the gas valve and fire the igniter. Propane flows to the burner, the igniter creates a spark, and the flame lights. The flame heats the heat exchanger, and the blower pushes air across the exchanger and into the RV through the duct system.

This sequence has to happen in the right order with the right timing. A failure at any point in the chain shuts the whole system down as a safety precaution. That's a good thing (you don't want unburned propane accumulating), but it means a single faulty component can prevent the entire furnace from operating.

Common furnace problems we fix in Jensen Beach

Furnace won't ignite. The blower runs, you hear the gas valve click, but there's no flame. In Jensen Beach, the number one cause is insect debris in the burner tube. Mud daubers (a type of wasp) build clay nests inside the tube during summer months, blocking gas flow. We clean the burner tube and check the igniter electrode. If the electrode is cracked or coated with carbon, we replace it. This repair runs $100 to $175.

Blower runs but no heat. This means the blower motor works but the ignition sequence isn't completing. The most common cause is a failed sail switch. The sail switch is a small flap inside the air intake that confirms the blower is generating sufficient airflow. If it's stuck, bent, or dirty, it won't close and the control board won't allow ignition. Sail switch replacement costs $100 to $200.

Furnace short cycles. The furnace fires up, runs for 30 to 60 seconds, then shuts off and tries again. This rapid on-off pattern usually indicates the high-limit switch is tripping. The high-limit switch shuts the furnace down if the heat exchanger gets too hot, which happens when airflow is restricted. Blocked ducts, closed vents, or a failing blower motor that's not moving enough air are the usual culprits.

Blower motor won't run at all. If you turn up the thermostat and hear nothing, check the fuse first. RV furnaces run on 12V DC power, and the fuse is often a 15-amp blade fuse in the distribution panel. If the fuse is good, the problem is either the thermostat, the control board, or the blower motor itself. Motor replacement runs $175 to $350.

Strange noises during operation. A high-pitched whine usually means the blower motor bearings are failing. A rumbling or popping sound from the combustion chamber indicates delayed ignition (gas is accumulating before the spark catches). A rattling from the ductwork means connections have loosened from vibration during travel.

Propane smell when the furnace runs. Turn it off immediately and ventilate the RV. A gas smell during operation means there's a leak in the gas line to the furnace, a crack in the combustion chamber, or an exhaust blockage that's pushing combustion gases into the living space. This is a safety issue that needs immediate professional attention.

The insect problem: Jensen Beach's top furnace killer

We can't stress this enough: insects are the leading cause of RV furnace failures in Jensen Beach. During the 7 to 8 months your furnace sits idle, mud daubers, dirt daubers, and other wasps build nests inside the burner tube and exhaust vent. Spiders spin webs across openings. Ants create colonies in the ductwork.

A mud dauber nest just 2 inches long inside the burner tube is enough to completely block gas flow and prevent ignition. Even a spider web across the exhaust vent can restrict airflow enough to cause the high-limit switch to trip.

The best prevention is installing insect screens on the furnace intake and exhaust vents. These mesh screens let air flow freely but block insects from entering. We install them for about $35 to $50, and they save you a service call almost every season. If your RV doesn't have them, ask us to add them during your next visit.

Pre-season furnace service

The smartest thing any Jensen Beach RV owner can do is schedule a furnace service in October, before the first cold snap. Our pre-season service takes about 60 to 90 minutes and covers the following.

We remove and inspect the burner assembly, cleaning out any insect nests or debris. We test the igniter for proper spark and replace it if it's weak. We check the sail switch operation and adjust or replace it as needed. The blower motor gets tested for proper speed and current draw. We inspect the heat exchanger for cracks or corrosion. The ductwork gets checked for disconnections, leaks, or blockages. And we verify proper gas pressure at the furnace.

This service costs $125 to $175 and gives you confidence that your furnace will fire up reliably when you need it. About 30% of the time, we find something during the pre-season check that would have caused a failure on that first cold night. Catching it in advance means a quick, inexpensive fix instead of an emergency service call.

When to repair vs. replace your RV furnace

RV furnaces are relatively simple appliances, and most can be repaired cost-effectively. Individual component failures (igniters, sail switches, blower motors, control boards) are almost always worth repairing. A $200 blower motor replacement on a $600 furnace makes sense every time.

Replacement makes more sense when the heat exchanger is cracked (that's the most expensive component, often $300+ just for the part), when the furnace is over 15 years old with multiple failing components, or when the BTU rating doesn't match your RV's heating needs (older units tend to be undersized for larger floorplans).

Need your furnace checked or repaired? Call Scott at 772-356-0328 for mobile service anywhere in Jensen Beach, Stuart, Palm City, or Martin County.