Reznor Heater Troubleshooting Manual [A Complete Guide]

The user requires the Reznor heater troubleshooting manual or guide to combat several issues. The major troubles are the Reznor heater won’t ignite, the heater not working or keeps shutting off, and the heater turns on and off. 

Also, the other Reznor heater problems are the heater’s temperature issue, i.e., not heating and overheating, the heater blowing cold air, error codes, the venter motor won’t start, the heater not turning on and the heater’s fan issues.

You can try to resolve all these above issues by resetting your Reznor heater and properly maintaining it. Also, replace the faulty igniter and thermostat to solve the ignition problem. 

Thoroughly read this article till the end, and you will surely learn the above issue’s precise cause and solutions. So, let’s start…

Why Do Issues Take Place In Your Reznor Heater?

After using your Reznor heater for some time, you may experience your heater not turning on, keep shutting off, and not providing you with the service properly. Actually, a new heater will not create these issues.

When you use the heater continuously but don’t concentrate on its maintenance and other factors, you face all these problems. Mainly your Reznor heater may start malfunctioning for the following reasons:

  • Lack of proper maintenance.
  • Wear and tear of components.
  • Old aged heater.

Reznor Heater Troubleshooting Manual [9 Easy Solutions]

The following guide has all the details of the major factors responsible for each Reznor heater problem and their practical solutions.

Note: You can also read how to fix Mr Heater big maxx problems.

1. Reznor Heater Not Igniting

One of the major Reznor heater problems is that your Reznor heater won’t ignite. The fan fails to kick on after turning on the heater, and the burners don’t create fire. Your Reznor heater will not ignite mainly for the following reasons: 

  • Dirty or damaged flame sensor or igniter.
  • Faulty main valve (Valve is not working or getting enough voltage).
  • Bad burner relay.
  • Burner’s improper air shutter adjustment (Too closed or too open).
  • Air in the gas line/No gas supply.
  • Too low or too high gas pressure.
  • Defective venter motor and Diaphragm.
  • A shot build-up in the venter motor.
  • Thermocouple malfunction.  
  • Blocked exhaust pipe or vacuum tube.


If you experience your Reznor heater won’t light, you should do the following to resolve the above troubles:

  • Properly clean the dirty igniter and replace the corroded flame sensor.
  • Make sure the igniter is working perfectly.
  • Check the burner’s air shutter and adequately adjust it.
  • Replace the lousy burner relay, faulty Diaphragm and venter motor, and defective thermocouple.
  • Ensure the burner’s proper air shutter adjustment.
  • Make sure the gas pressure is perfect.
  • Clean the venter motor’s shoot buildup.
  • Ensure your heater has enough gas supply.
  • Remove the vacuum tube and exhaust pipe’s blockage.

2. Heater Keeps Shutting Off

You turn on your heater, but after running for a few seconds, your Reznor heater keeps shutting off, and this is a common problem you may encounter. The following factors are responsible for which your Reznor heater pilot won’t stay lit.

  • Airflow blockage.
  • Dirty or corroded flame sensor.
  • Thermocouple malfunction.
  • Closed gas valve.
  • The faulty or damaged heating element.
  • Loose wire connection. 
  • Defective gas burner.
  • Blocked pilot tube.


If you are suffering from the issue that your Reznor heater won’t stay running or won’t fire constantly, then you should follow the fixing ways below:

  • Make sure your heater is getting sufficient air and remove the airflow blockage.
  • Replace the damaged flame sensor and adequately clean the dirty sensor.
  • Replace the lousy thermocouple, corroded heating element, and faulty gas burner.
  • Make sure the heater’s gas valve is open.
  • Check your heater’s wire connection and tighten it.
  • Remove the pilot tube’s blockage.

3. Reznor Heater Turns On And Off

Suddenly you may experience your Reznor heater not working, and it constantly keeps cycling on and off. If you experience this issue, be sure that the following factors are causing it:

  • Heater’s inappropriate gas pressure (Too low or too high pressure).
  • The burner relay is not grounded properly.
  • Faulty flame sensor.
  • Cracked or damaged insulation.
  • Polarity switch issue.
  • Burner relay malfunction.
  • Circuit board malfunction.
  • Bad combustion air proving switch.
  • Incorrect polarity.


The resolving ways of the above trouble are the following:

  • Check your heater’s gas pressure (For natural gas, the pressure is 15 mbar and for propane gas, the pressure is 37 mbar).
  • Make sure the burner relay is grounded correctly.
  • Replace the defective flame sensor, cracked insulation, lousy polarity switch, bad burner relay, and malfunctioning combustion air proving switch.  
  • Inspect your home’s circuit board and replace the faulty one.
  • Check the polarity switch and reverse the terminal block connection’s voltage wireline.
  • Ensure your heater’s correct polarity.

4. Heater’s Temperature Issues

Two major temperature issues are Reznor heater not heating and Reznor heater overheating. Several factors are accountable for overheating and no heating issues. Let’s discuss the details causes of each problem separately:

i) Reznor Heater Not Heating

When your Reznor heater stops heating, you will get no warm air from it. The following causes are the culprit for the Reznor heater no heat issue:

  • Dirt buildup in the heater or clogged heater.
  • Blown up power supply.
  • Tripped circuit breaker.
  • Heat exchanger malfunction.
  • Insufficient airflow.
  • Faulty thermostat.
  • Incorrect valve outlet pressure.
  • Improper adjustment or location of the thermostat.


If your heater stop heating, follow the solution below to fix your above troubles:

  • Properly clean your heater’s blockage and remove the dirt or debris buildup in it.
  • Replace the tripped circuit breaker, defective power supply, faulty heat exchanger, and bad thermostat.
  • Ensure your heater is getting sufficient airflow.
  • Make sure your heater is operating at the correct valve outlet pressure.
  • Properly adjust the thermostat and correctly install it in its location.

ii) Reznor Heater Overheating

The factors that cause your Reznor heater to overheat are:

  • Faulty high limit switch.
  • Defective blower fan and vent fan.
  • Poor air circulation.
  • Dirty or clogged air filter.
  • Bad heat exchanger.


The easy ways to get rid of these above troubles are:

  • Replace your heater’s lousy high limit switch, bad vent fan and blower fan and defective heat exchanger.
  • Ensure that the air circulation is perfect and there is no lack of air supply in the heater.
  • Properly clean the dirty air filter and remove the blockage.

5. Venter Motor Stops Starting

Another trouble you may encounter with your Reznor heater is that suddenly its venter motor stops starting. The concerning causes of it are:

  • The heater doesn’t have any power.
  • Integrated circuit board’s blown fuse.
  • The Venter motor doesn’t have any power.
  • Faulty venter motor.
  • Circuit board malfunction.


Fix all the above trouble by following the effective ways below:

  • Check the heater’s power supply source and make sure the heater has enough power.
  • Replace the blown fuse in the integrated circuit board.
  • Ensure the venter motor has enough power and it is operating perfectly.

6. Heater Blowing Cold Air

Reznor heater not blowing hot air is one of the main problems that the users often encounter. Reznor heater blowing cold air is a major sign that there is something wrong with your heater. The causes of it are:

  • A clogged or dirty filter.
  • Tripped manual reset.
  • The actual temperature is greater than the thermostat setting.
  • The Fan switch is “ON.”


Follow the tips below to solve the above trouble:

  • Remove the air filter’s blockage and adequately clean the dirty filter.
  • Replace the tripped manual reset.
  • Make sure the actual temperature is lower than the thermostat setting.
  • Ensure the fan switch is in the “Off” position.
  • Replace the defective venter motor and malfunctioning circuit board.

7. Reznor Heater Not Turning On

After several turning attempts, your Reznor garage heater is not working mainly due to the following reasons: 

  • Faulty fan or fan motor. 
  • Insufficient airflow. 
  • Clogged air filter. 
  • Blocked registers.


The fixing ways of all these above troubles are: 

  • Replace the broken fan, obstructed blades, and brunt motors. 
  • Ensure the heater is getting sufficient airflow. 
  • Remove the register’s blockage and adequately clean the clogged air filter. 

8. Reznor Heater’s Fan Issues

The central 3 problems with the Reznor heater’s fan are suddenly the fan stops working, the fan runs continuously and won’t shut off, and the fan cycles on and off. Now let’s discuss the causes and solutions of each of these in detail:

i) Reznor Heater Fan Not Working

For the following reasons, your Reznor heater fan stops working:

  • Open circuit or integrated circuit board malfunction.
  • Faulty starter or motor.
  • The heater is not getting enough power to run.
  • Burner relay and venter motor terminal’s faulty connections.
  • Damaged integrated burner relay.
  • Blown fuse.
  • Open LC1 and LC3 of your Reznor garage heater.
  • Lockout heater.
  • Thermostat malfunction.


Follow the ways mentioned below to fix all these above troubles:

  • Check your heater’s wiring and connections and make sure the heater is closed.
  • Replace the lousy motor or starter, faulty integrated circuit board, corroded integrated burner relay, blown fuse, and defective thermostat.
  • Make sure your heater is getting power adequately to operate.
  • Ensure proper connections between the burner relay and the venter motor.
  • Check your Reznor garage heater’s LC1 and LC3 and ensure both are closed.
  • Reset your heater to get it away from the lockout mode. 

ii) Reznor Heater Fan Won’t Shut Off

If, after shutting off your heater’s thermostat still, the fan keeps running and won’t shut off, then the following factors are causing this issue:

  • The auto setting of the fan’s limit switch.
  • Defective thermostat wiring.
  • Fan’s faulty limit switch.


If the heater stops but still the fan runs continuously, you should do the following to fix it:

  •  The fan’s limit switch is set to Off.
  • Check the thermostat wiring and replace the faulty wire connection.
  •  Replace the fan’s lousy limit switch. 

iii) Reznor Heater Fan Cycles On and Off

Reznor heater fan cycling on and off indicates there is something wrong with your heater’s internal thermal protection device. The factors causing it are:

  • Motor overload device
  • Fan’s defective switch or relay (On/Off)
  • Faulty limit switch
  • Bad thermostat


When the burner is on but your heater’s fan cycles on and off, compare your heater’s motor rating and motor load plate. And do the following:

  • Replace the faulty fan switch, malfunctioning limit switch, and defective thermostat.

9. Reznor Heater Error Codes

Flashing green light and yellow light on your Reznor heater’s display indicates its error codes. Greenlight and yellow light flashing at different numbers convey different meanings. Let’s discuss these error code’s meanings in detail:

i) Reznor Heater Green Light Flashing

When something wrong happens in your heater, you will experience the Reznor heater green light flashing issue. Depending on the type of problem, your Reznor heater may flash the following number of lights:

  • Reznor Heater 2 Flashes: Reznor heater lockoutheater fails to sustain or detect a flame 
  • Reznor Heater 3 Flashes: open or closed pressure switch. 
  • Reznor Heater 4 Flashes: Open flame rollout or high limit switch. 
  • Reznor Heater 5 Flashes: The heater sensed the flame, but the gas valve was not energized. 


If you see Reznor heater error codes on its display, you should press the Reznor heater reset button to reset your heater. The other effective fixing ways are:

  • Reznor Heater 2 Flashes: Make sure the flame is not going out, and the heater is sensing the flame
  • Reznor Heater 3 Flashes: Check the pressure switch and alter the button in the opposite direction
  • Reznor Heater 4 Flashes: Inspect the flame rollout or high limit switch and replace the defective switch
  • Reznor Heater 5 Flashes: Ensure the gas valve is fully energized, and the heater is perfectly sensing the flame

ii) Reznor Heater Yellow Light Flashing

Yellow LED codes indicate your Reznor heater’s flame status. The Yellow LED codes show the following 3 situations:

  • Steady On – Flame is correctly sensed
  • Slow Flash – It means weak flame (when the current level is below 1.0 microamps, it occurs)
  • Fast Flash – It indicates the heater’s undesired flame (It has no call for heat and open valve)

How To Reset Reznor Garage Heater

If you see your Reznor heater flashing green lights, yellow lights, or other error codes, you can quickly solve the issue by resetting your heater.

Also, if your heater goes into lockout mode, you need to reset it. The easy resetting steps for your Reznor garage heater are: 

  • Press your Reznor heater controller’s red button. 
  • For 3 seconds, hold down the reset button. 
  • Ensure oil properly gets to the heater’s nozzle by pushing out the air, and your Rozner heater will fire up.

Reznor Garage Heater Maintenance Tips

Regular maintenance is essential for keeping your Reznor Garage heater perfect and up to date. Increasing the performance and longevity of your heater requires correct maintenance. However, some tips for maintaining your heater are:

  • Properly clean your heater motor, blade, and fan guard’s dust, lint, and grease. Dirt is a primary culprit which stops your heater’s smooth functioning and lowers its component’s durability. Thus frequently clean your heater following a maintenance routine.
  • Regularly inspect your heater’s heat exchanger to find out the internal and external damage.
  • Frequently inspect whether there are any defects in vents. If so, immediately replace the vent’s damaged parts.
  • Also, check loose and corroded wiring, and replace the damaged wire connection.
  • When replacing your heater’s defective parts, make sure that you are using manufacturer-approved components. 


Where is the reset button on the Reznor heater?

The controller’s red button in the Reznor heater is its reset button. Hold down the reset button for 3 seconds to reset your Reznor heater.

How do you reset a pilot light?

Set the heater’s gas valve on the pilot for resetting your pilot light. Ensure the gas enters the pilot by holding down the bypass button. Hold the button for some time. Insert a flame into your heater’s pilot by using a barbecue lighter.

How do you fix the pilot light on a gas heater?

To fix your gas heater’s pilot light, you should inspect its thermocouple, gas level, and corroded pilot tips. Also, regulate the drafts and adequately adjust your pilot light’s irregular flame.

Why is my Reznor heater heating fan not working?

Your Reznor heater’s heating fan stops working due to a faulty blower, tripped circuit breaker, incorrect wiring, motor issues, and a defective thermostat.


We explained the A-Z details of each problem in this Reznor heater troubleshooting guide. Hopefully, following the above solutions, you can now fix your heater’s issues by yourself.

Still, if you have any other queries regarding the Reznor heater, let us know through comments. We’ll give you the answer.

About William

William is the founder of He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

4 thoughts on “Reznor Heater Troubleshooting Manual [A Complete Guide]”

  1. My Reznor heater works great till the temperatures get into the minus the the fan only works for a short time and when it get warmer it starts working like a charm again.

  2. My Reznor shop heater is set to maintain 45 degrees unless I do a override when I wish to be in the shop. Lately I find that the temperature in the shop is much lower than the 45 degrees hold requested. Upon bumping up the temperature at the thermostat, the heater does not respond until I cycle the AC input. I.e turn the breaker on and off. I recently replaced the thermostat and control panel as well as inspected the igniter. Not sure what is left that could have failed.
    Thanks for your support.

    • Hi Doug

      As you have already replaced the thermostat & control panel, now, check & ensure all the ventings are blockage free.
      If it doesn’t bring luck, reset the heater to fix the issue.

      If still you face this heater problem again, contact the Reznor customer support center.

      Best of luck!


Leave a Comment