RV Furnace Diagnosis:

Example of things we are testing during a bench test and some of the components: Checking Current, Voltage, Resistance, DC and AC power, Circuit Board, Relay, Blower Motor, Sail Switch, High Limit Switch, Gas Valve, Igniter, Flame Sensor.

Safety disclaimer: It’s important to note your RV furnace operates using propane and electricity, two potentially dangerous sources.

If you are not confident in working with either, allow a professional technician to take care of the repairs.

How Does an RV Furnace Work?

Here is the basic sequence of operations:

1. The thermostat sends an electrical signal to the furnace circuit board.

2. The signal passes through a relay and the blower motor starts.

3. At full speed, it activates the sail switch confirming there is adequate airflow to exhaust fumes from the furnace.

4. The signal continues to the high-level switch which indicates the temperature of the furnace is below a safe level to start.

5. With the two previous safety switches activated, the gas valve opens allowing propane into the combustion chamber.

6. The igniter in the combustion chamber receives current from the ignition module on the circuit board. As a result, the current produces a spark between the ignitor tips. This lights the fuel and produces the flame resulting in the heat flowing through the heating ducts throughout your RV.

Complaint: Furnace not operating properly.

Cause: Was an intermittent condition from the PC board.

Cure: Along with serving the unit, the PC board was replaced. This unit was actually installed twice and didn’t ended up failing during the testing process.

Customers came in to pick up and during testing with owners the unit failed to operate during cycles.

Removed the unit for the 2nd time and after testing and monitoring found the PC Board was the issue.

If you’ve determined the circuit board is the cause of your furnace problem, it’s a relatively easy part to replace. The circuit board is usually located in the furnace’s blower chamber near the bottom of the unit.

The hard part is having to remove the furnace to access it for testing and bench testing.

Lucky everything was repaired and reinstalled and tested properly.

More from Dustin

Read more of Dustin’s articles here.

Dustin owns and operates California RV Specialists, an independent RV repair shop located in Lodi, CA. He thrives on sharing his knowledge and enthusiasm of RV repair and maintenance with his team, customers, and virtual friends.

Be sure to check out his YouTube channel, where he shares what’s going on in the shop and the product offerings in the store. Dustin is also very active on Facebook. Join his group, RV Repairs and Tips – What’s in the shop!

Dustin proudly operates the business alongside his wife, Ashley; but the true pair that run the show are their Boston Terriers, Arvie and Hitch.