How to Find and Fix RV Propane Leaks Behind Your Refrigerator - Safety Guide

Bottom Line Up Front

Based on your description of the "pfft" sound returning after replacing the Norcold fridge valve, you likely have a second small leak in your propane system, possibly near the furnace as your sniffer detected. The fact that you don't hear the pfft when propane is actively being used confirms this - gas flows to the appliances instead of escaping through the small leak. While some very minor pressure drop over extended periods (several hours) can be considered normal due to temperature changes and system expansion, a 15-minute pressure loss with an audible "pfft" indicates an actual leak that needs repair, not just normal system behavior.

Root Causes

Your situation involves multiple factors creating a complex leak scenario. The original Norcold fridge valve leak around the gas valve stem packing was successfully resolved, but you've uncovered a secondary leak likely in the furnace area. This is common - when one leak is large enough to mask others, fixing the primary leak often reveals smaller secondary leaks that were always present.

The "pfft" sound you're hearing represents gas escaping when you open the tank valve after an extended shutoff. This happens because the system tries to pressurize, but gas escapes through the leak faster than it can build pressure. When appliances are running, they create demand that pulls gas through the lines faster than it can escape through small leaks, which explains why you don't smell propane during active use.

Temperature changes and normal system expansion don't typically cause audible pressure loss within 15 minutes. True system settling might take hours and would be silent. Your sniffer detecting gas under the coach near the furnace strongly suggests a fitting, connection, or valve issue in that area.

Before You Start

Safety is paramount when dealing with propane leaks. Ensure your propane tank is shut off before beginning any inspection work. Have your electronic sniffer ready and fully charged, along with a spray bottle containing soapy water for bubble testing. Work in well-ventilated conditions and avoid any ignition sources.

Gather the necessary tools including adjustable wrenches, pipe dope or thread sealant rated for propane, and possibly replacement fittings. Since you mentioned the furnace area, you may need to access compartments or remove panels to reach all connections. Take photos before disconnecting anything to ensure proper reassembly.

Document your findings as you go. Note exactly where your sniffer gives readings and the strength of those readings. This systematic approach will help you prioritize which leaks to address first and ensure you don't miss any problem areas.

The Repair Process

Start by conducting a systematic pressure test to isolate the leak location. With the tank valve closed, close all appliance valves, then turn on a burner briefly to depressurize the system completely through that single point. Then slowly open the tank valve while listening for the "pfft" sound. The sound's location and your sniffer readings will guide you to the problem area.

Focus your inspection on the furnace area where your sniffer detected gas. Check all threaded connections, including the gas valve on the furnace itself, any unions or couplings in the gas line, and connections at regulators or tees. Apply soapy water to each joint while the system is pressurized at normal operating pressure (10-11 inches water column) - even tiny bubbles indicate leaks that need attention.

For loose fittings, try tightening them first, but don't over-tighten as this can damage threads or fittings. If tightening doesn't resolve the leak, you'll need to disconnect the fitting, clean the threads, apply fresh propane-rated thread sealant, and reconnect. Use products specifically rated for propane - regular plumbing compounds may not be suitable.

After making repairs, conduct a thorough system test. Pressurize the system and wait 30 minutes, checking with both your sniffer and soapy water. The "pfft" sound should be eliminated, and you should maintain steady pressure. Test the system under load by running appliances to ensure proper operation and no new leaks develop under flow conditions.

Professional Help Needed

If you cannot locate the source of the leak after thorough inspection, or if the leak appears to be within a gas appliance rather than at external connections, it's time for professional intervention. Propane system leaks inside appliances often require specialized knowledge and tools to repair safely.

Consider professional help if you discover multiple leaks, as this might indicate broader system issues such as vibration damage, corrosion, or improper installation. An RV propane technician can perform a comprehensive system inspection and pressure test that might reveal problems not apparent during basic troubleshooting.

Additionally, if you're uncomfortable working with propane connections or lack confidence in your repair abilities, don't hesitate to seek professional assistance. The cost of professional repair is minimal compared to the potential consequences of an improperly repaired propane leak. Many RV service centers can perform propane system inspections and repairs, and some mobile technicians specialize in this type of work.