RV FURNACE TROUBLESHOOTING – DSI Only

My RV Furnace does not work.

Electronic Ignition Models only – DSI

Only qualified technicians should work on RV furnaces.  If you are not qualified to work on this appliance please do not do so.  Safety First.

We have tried to list the things that should be checked first before a technician is contacted.  We also list some of the problems the technician might find.

A.  The blower does not run:

1.   12 Volt Power below 10.5 volts and a maximum of 13.5 volts.

       Measure the voltage at the furnace and confirm proper voltage.

2.   Thermostat contacts dirty – clean the contacts with a business card.

       Hold the business card between the contacts and drag in thru the contacts.

3.    Thermostat on/off switch is bad. – Replace the on/off switch.

4.    Shorted or broken wires from the circuit board to the thermostat.

       Replace or repair the broken/shorted wires.

5.    Bad thermostat – replace the thermostat.

CAUTION: Do not to attempt to short out the thermostat wire for a test, you 

       will damage the thermostat.

6.    Bad ground or broken wires. – Repair broken wire or repair the ground.   

7.    Bad thermostat relay – replace thermostat relay.

8.    Bad time delay relay – replace time delay relay.

9.    Blown fuse or tripped circuit breaker – Reset breaker and change the fuse

       with the same size fuse.  The cause most be found if we have repeated fuse

       and circuit breaker trips.

10.  Bad fan motor – replace the motor.

B.   The Blower runs, but no ignition:

1.     Low voltage – check the voltage at the furnace, a minimum of 10.5 volts.

2.     Fan motor is bad – replace the fan motor.

3.     Low LP pressure or bad LP gas.  Check for 11” water column with at least

        two LP gas appliances running.   Have your LP distributor add alcohol to

        your tank – this will absorb extra moisture in the tank.   Ask if winter or

        summer LP was in your last fill.

4.     Check the air intake and exhaust vents for obstructions – wasp nests, etc, –

        Clean out the obstructions.

5.     Bad wire to the electrode – repair or replace this wire.

6.     Electrode is cracked or out of adjustment – Replace or adjust the electrode

        gap to 1/8 inch.

7.     A dirty burner – clean out the burner.

8.     High limit switch is bad – replace the high limit switch with the same

        ratings.

9.     Sail switch is dirty or bad – Clean or replace the sail switch.

10.   Gas valve is bad – Replace the gas valve or the individual coils.  They

        should read between 30 to 50 ohms.

11.   Control board is bad – Replace the control board.  We like the Dinosaur

        brand.

C.   The burner ignites – but goes our after a short period of time:

1.    The LP gas pressure is too low – 11” water column is measure with two or

       more LP gas appliances operating.

2.    The air intake and exhaust vents are blocked – clear the obstructions of

       nests or other debris.

3.    The electrodes are out of adjustment, cracked or dirty.  –  Adjust and clean

       or replace the electrodes.

4.    The burner is dirty – clean the burner.

D.   Black streaks from the exhaust vent – sooting.

1.     Intake or exhaust vent obstructed – clean out these vents.

2.     Low LP gas pressure – adjust the gas pressure to 11” water column with

        two gas appliances operating.

3.     The burner is dirty – Cast iron burners are more prone to this ailment.

        Clean the burner.

4.     Fan motor is bad – Replace the fan motor – Caution: the blower wheels

         need to be handled gently – a bent lower wheel will tend to be noisy.

E.    Insufficient heat:

       1.     Low LP gas pressure:  adjust the gas pressure to 11” water column

        with two gas appliances operating.

2.     An LP gas line that is crimped.  – Replace the line with like materials.

3.     In below freezing temperatures – Question which gas was used in your last

        fill; summer or winter LP.

4.     Is your tank large enough to accommodate a sufficient volume of gas for   

        the amount of fuel used in a given time?  Ask your LP distributor.

SEQUENCE OF OPERATION:

1.     The thermostat calls for heat.

2.     The time delay relay or thermostat relay and controls the power to the

         blower.

3.      The sail switch operates at 75% blower speed.

4.      Power is routed thru the high limit switch to the control board ignition

         function.

5.      The ignition function on the control board opens the gas valve and

         provides a spark to the electrodes.

6.      The burner ignites and burns until the thermostat is satisfied.

7.      The gas valve closes, and the burner goes out.

8.      The fan runs enough to cool the furnace down.

Consult with your manufacturer for your specific make and model, or review your installation manual as well as your operators manual for more detailed troubleshooting techniques.

 Happy Camping

     RV101byFred.com

        Fred Brandeberry