Suburban SF-35 Furnace Troubleshooting (Won’t Ignite)

Trying to stay warm can be an ongoing battle when you are camping at higher altitudes. It doesn’t help your sleep when your furnace decides to quit working at that time. But if you know how to do the right repairs, you can stay warm even on a mountain top.

There are many sources of this problem. One would be propane supply. If your tank is running out of fuel, that may be one source. Fortunately, it is an easy fix. All it takes is a short drive into town to refill the tank.

To learn more about the different sources for this problem, just continue to read our article. It goes through those options and helps you find the best solution for your specific situation. Take a few minutes to see how this important information can help you when you get cold.

How do You Troubleshoot a Suburban RV Furnace?


The first step would be to check your warranties. Do not do any work on the furnace yourself if your warranties are still valid. You do not want to run the risk of having them voided. Manufacturers are quick on the trigger to cancel the protection they provide.

If you are under warranty, call an approved repairman. Let them handle the investigation and work. That way you stay protect until your coverage runs out.

If you are not under warranty, then start doing some investigating. There are many parts that can fail and stop your furnace from igniting. Of course, you will need to be able to recognize a bad part from a good one so take your time on this.

Do some tests and make sure to check your propane tank for low fuel, your vents for nests and other obstructions, as well as the propane line itself. After that search, you can start looking at specific parts.

One problem could be the regulator. To find out if that is the case, light your stove and if a burner goes out when you try lighting your furnace, then you have a regulator problem.

This is a step-by-step process that only stops when you find the part or parts that have failed.

Suburban SF-35 Furnace Troubleshooting Guide

If your propane tank has gas in it and there are no obstructions, then start checking different parts to see if they are functioning okay. One part to check is the flame sensor.

If you are getting cold air even during the lockdown mode, then this part is the culprit. It is faulty and does not read the fuel supply properly. The best fix for this would be to replace the sensor.

Or it could be poor air intake, exhaust, or the same for gas flow. Check your vents and pipes to make sure there are no obstructions of any kind. Yes, you will have to check the lengths of those items completely.

The control board only allows roughly 7 seconds for the sensor to report a flame is present. If it doesn’t get that message it will go into re-ignite mode. After the third time, it will enter lockdown mode.

These are just a couple of ideas. You will have to check the next section for the download manuals and see what other problems the manufacturer says can be the problem.

Download Suburban SF-35 Furnace Manual


The biggest hassle about downloading manuals is that you never know what they will cost. Some websites do it for free or allow you to view the manual but charge you for a download.

You have to be careful about which website you use. The best option is to always go to Suburban first and see if they have free manual download. They should have manuals so that is always a safe place to go when yours is missing.

Our go-to website for manuals is this link. It is a very reliable company when it comes to manuals. It is well put together and you can find a wide variety of Suburban manuals for other appliances you may own.

One more source is this website but it only shows a generic manual for Suburban gas furnaces. A final website we will link to is this one. You can pick the exact manual you need from its list.

If you do not want to download a manual, just go to any Suburban dealer or approved repairman and see what they have in stock. Then you can ask any questions you may have about your furnace at the same time.

A good internet search will help you get more manual issuing websites if those locations do not work for you.

Suburban SF-30FQ Won't Ignite


One of the first places to check will be your regulator. When it fails, it can stop your furnace from getting the gas it needs while supplying it to another appliance without trouble.

After the regulator, you can try to check the limit switch and the sail switch. Both of these smaller parts can easily fail and cut off the gas supply. You may also have to replace one or two whips. They can lose their seal and leak when handled.

As mentioned earlier, the problem could lie with the sensor or the control board. The only solution to these many potential sources is a replacement. You will need to buy new parts and fortunately, those parts should still be available in great numbers.

You should also check the flame rod for possible damage. If it has built up some white or red rust then this coating will block the rod’s operation. You would have to remove the rod and give it a good cleaning.

Another issue with the flame rod would be that it is out of position. This can happen due to the bumps you hit or the vibrations from long-term driving. The fix for this is to re-adjust it back to factory settings.

Or it could be a stuck check valve in the hose near the propane tank. This is supposed to be an easy access, easy fix as well as inexpensive. Another easy fix would be to unplug the harness and clean up the connection with a pencil eraser.

Where is The Reset Button on a Suburban RV Furnace?


While this may or may not apply to this model of Suburban furnace. The most common place to find the reset button on most furnace models is inside the blower compartment.

Or this is the type where you only have to shut the power off to the furnace for about 5 minutes or so and then restart the power again. That should reset the system if you can’t find the reset button.

In looking at the manual, we did not see a reset button on any of the diagrams we saw. You may have to call a dealer or a repairman if those two options above are not working on your model of furnace.

The reset button may be there but it may not be important enough to list on those diagrams. Download a manual if you do not have one and scour those pages to see if one is mentioned or not.

Where To Find Replacement Parts


When you are troubleshooting your Suburban SF-35 furnace, you want to make sure parts are easy to come by and close to you. The answer to the first part is yes, they are easy to come by.

The answer to the second part is that you will have to determine what is close to you. Some outlets on our results page sell a tune-up kit. These kits should help make sure your furnace stays in top working order.

These kits cost anywhere between $90 and 4150 approx., and they provide all the necessary parts to tune that furnace up. As for being near, you, Amazon is as close as it gets with its vast delivery system.

That marketplace has a lot of Suburban furnace parts and you just have to pick the right one that you need. Then you will get that delivery quickly if you qualify for their quick delivery system

If you can’t wait for Amazon, there are plenty of online parts stores that are selling the parts you will need. All you have to do is find their location, contact them if they are close, and ask if they have that part.

Make sure to have the serial or model number of the part you need to speed up the service.

Some Final Words

Troubleshooting your Suburban furnace is not going to be difficult if you know what you are doing. Also, it will be easier to DIY it when you are not under warranty coverage and the parts are close by.

Do a good internet search to find a dealer or approved repairman near you. That way you can get those parts fast and be warm at night once again. The repairs shouldn’t take that long to do, furnaces are simple devices.

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