RV Furnace Clicks but Blower Won’t Start: Causes and Fixes

The RV furnace clicks but blower won’t start is a common problem RV owners face during cold-weather travel and storage. This article explains likely causes, diagnostic steps, and practical repairs to restore heat safely and quickly while highlighting when to seek professional help. A concise summary table follows to guide troubleshooting.

Symptom	Possible Cause	Quick Action
Clicking at furnace but blower silent	Thermostat signal, limit switch, or control board	Check thermostat and circuit power
Clicking then furnace lights but fan doesn’t run	Blower motor, capacitor, or wiring	Inspect motor and capacitor, test 12V or 120V supply
Intermittent clicking, no heat	Gas valve or igniter issues	Examine igniter and gas supply, then call tech

How RV Furnace Systems Work

An RV furnace typically consists of a thermostat, control board or module, igniter, gas valve, burner assembly, combustion chamber, limit switch, and a blower motor with fan blades. Many RV furnaces run on 12V DC for controls and 120V AC for some blowers depending on model. When the thermostat demands heat, the control board sequences power: it sparks or heats the igniter, opens the gas valve, senses flame, then energizes the blower to circulate warm air. A failure at any step can produce clicking without blower operation.

Common Causes When The RV Furnace Clicks But Blower Won’t Start

1. Thermostat Or Control Signal Problems

Faulty thermostat settings, loose wiring, or a failed thermostat can send an intermittent or absent signal to the furnace control board. A control board that receives a startup signal but cannot progress may emit clicking as relays or solenoids attempt to engage. Check the thermostat first because it’s an easy and frequent culprit.

2. Blower Motor Failure

The blower motor can seize, suffer worn brushes, or develop internal electrical faults. When the igniter or relay clicks but the blower does not receive or act on power, the motor is a likely suspect. Motors on older furnaces often fail after years of dust, moisture, and vibration.

3. Failed Capacitor

Many blower motors rely on a start or run capacitor to provide torque at startup. A weak or failed capacitor will produce clicking from the relay while the motor can’t get going. Capacitor failure is common and relatively inexpensive to replace.

4. Limit Switch Or Safety Interlock Engaged

Limit switches monitor furnace temperature and airflow. If a switch detects overheating or blocked airflow, it will prevent the blower or gas valve from operating. Clicking may result from repeated attempts to reset. Dirty filters, blocked vents, or a stuck switch often cause this scenario.

5. Control Board Or Relay Problems

Control boards and relays handle sequencing and power distribution. Corroded connectors, water damage, or burned traces can cause clicking as relays chatter without sending stable power to the blower. Replacing the control board is sometimes necessary when diagnostics point to electronic failure.

6. Power Supply Or Fuse Issues

Low battery voltage, blown fuses, or poor ground connections can prevent the blower from receiving sufficient current. The control board or igniter might still click with minimal voltage, but the blower requires more power to start. Ensuring 12V or 120V supply integrity is essential.

Initial Troubleshooting Steps

Before disassembling the furnace, perform these safe, low-effort checks to narrow the cause when the RV furnace clicks but blower won’t start.

• Verify thermostat settings and replace batteries if applicable.
• Check the RV battery voltage or shore power; measure with a multimeter.
• Inspect fuses and circuit breakers related to the furnace circuit.
• Look for obvious signs of water, corrosion, rodent damage, or loose wiring at the furnace access panel.
• Ensure intake and exhaust vents are clear of debris, snow, or nesting material.

Diagnosing Electrical And Control Issues

Check Power And Ground

Using a multimeter, confirm the furnace receives the required 12V or 120V at the control board connection. Low voltage will often allow clicking but not the sustained current for motor startup. Also verify a good ground connection to prevent voltage drop under load.

Test The Thermostat Signal

Measure voltage across the thermostat output while calling for heat. If no control voltage is present, bypass the thermostat temporarily by shorting the heat call terminals to see if the furnace proceeds. If bypassing starts the sequence, replace or rewire the thermostat.

Inspect Fuses And Relays

Locate the furnace fuses on the control board and in the RV fuse block. Replace blown fuses with proper ratings. Listen for relays clicking and test relay continuity when energized. A relay that clicks but fails to pass current under load indicates a bad relay or board issue.

Testing The Blower Motor And Capacitor

Visual And Manual Checks

Disconnect power, remove the furnace access cover, and inspect the blower motor for debris, binding, or burnt smells. Manually spin the blower wheel to check for free rotation. Resistance or grinding suggests motor wear or foreign object interference.

Measure Motor Resistance

With power off, measure motor windings with an ohmmeter. Open or shorted windings indicate motor failure. Compare readings to manufacturer specifications if available.

Test Or Replace The Capacitor

Verify the capacitor using a capacitance meter or replace it with a known-good equivalent. Symptoms of a weak capacitor include clicking from the control board with the blower attempting and failing to start. Replacing capacitors often restores startup torque.

When The Igniter Works But Fan Doesn’t

If the furnace lights but the blower remains dead, the ignition system and gas valve are likely operating correctly while the blower circuit is failing. Focus on blower motor, capacitor, relay, and airflow safety switches. Some furnaces have a separate blower relay or triac on the control board that can fail while ignition functions continue.

Airflow Restrictions And Limit Switches

Clogged air filters, blocked ductwork, or restricted return vents can cause the furnace to overheat, tripping a limit switch that prevents the blower from engaging. Replace filters, clear ducts, and reset the limit switch if accessible. Replacing a faulty limit switch may be required if it does not reset properly.

Safety Tips And Best Practices

• Always disconnect power (both 12V and shore/generator) before working on the furnace to prevent shock or fire risk.
• Handle gas components cautiously; shut off gas supply when troubleshooting related to valves or lines.
• Use insulated tools and follow manufacturer service manuals for component locations and specifications.
• Wear eye protection and gloves when accessing internal parts.
• Document wiring and take photos before disconnecting connectors to ensure correct reassembly.

Common Parts To Inspect Or Replace

When diagnosing why an RV furnace clicks but blower won’t start, the most frequently replaced parts include the blower motor, start/run capacitor, thermostat, control board, relays, and limit switches. Costs vary widely: capacitors are inexpensive, motors and control boards are mid-range, while professional labor and gas system work increase expenses.

Step-By-Step Repair Checklist For DIYers

1. Confirm power and thermostat call for heat.
2. Check fuses and breakers; inspect wiring for corrosion.
3. Bypass thermostat to test furnace response.
4. Open access panel and visually inspect blower, motor, and capacitor.
5. Manually spin blower wheel and test capacitor and motor windings with a meter.
6. Test relays and measure voltage at the motor during attempted startup.
7. Replace the capacitor if readings are out of range; re-test.
8. If the motor is seized or windings are bad, consider motor replacement.
9. If control board relays fail, replace the board or relay assembly.
10. After repairs, test operation through multiple cycles and monitor for unusual noises or overheating.

When To Call A Professional

Seek professional RV HVAC service if the problem involves gas valves, persistent electrical faults, control board replacement, or if diagnostics are inconclusive. Certified technicians have tools to test gas pressure, flame sensors, and specialized components safely. If the RV furnace clicks but blower won’t start after basic checks, professional diagnosis reduces risk and can prevent costly mistakes.

Preventive Maintenance To Avoid Future Failures

Regular maintenance reduces the odds of the RV furnace clicking but blower won’t start. Clean or replace air filters seasonally, keep intake and exhaust vents clear, inspect wiring and connectors yearly, and run the furnace for short periods during storage to exercise components. Periodic lubrication of motor bearings where specified helps extend blower life.

Cost Estimates And Parts Sourcing

Typical part costs: capacitors $10–$40, thermostats $20–$150, blower motors $100–$400, control boards $150–$500. Labor for a tech visit can add $100–$300 depending on region and complexity. Genuine OEM parts are recommended for compatibility; many RV parts suppliers and online retailers stock furnace components. Always verify model compatibility before ordering.

Key Troubleshooting Quick Reference

• Clicking but no blower: Check capacitor, motor, power, and relay.
• Igniter clicks and lights but no fan: Focus on blower circuit and limit switch.
• Intermittent operation: Look for loose wires, corroded connectors, or low battery voltage.
• Smell of gas or strong fuel odor: Turn off gas and power immediately and contact a professional.

Resources And Further Reading

Consult the furnace manufacturer’s manual for model-specific diagrams and specifications. Reliable online RV forums, manufacturer support pages, and certified RV HVAC technicians provide additional troubleshooting guides. For gas-related concerns, consult a certified propane technician to ensure safety and compliance.