Furnace works sometimes and sometimes don't

[Sdt]

Sometimes the furnace will work and even not moving the next morning it won't. Been to the repair shop twice and they think it's fixed. Maybe a loose connection. It works for a few times, then it doesn't. Any one else have problems like this?

[Foiled Again]

Your profile says 2004 Safari. Presume furnace is original. Try with both propane tanks full and open. If that works, start chasing low pressure problems. Have it cleaned, the flue can get clogged with carbon. Check for tiny spiders in the propane jet. Then wire by wire check for loose connections. How is propane pressure at the tank? And at the furnace? Clear the propane line of any water. Try new propane bottles. You may have water and crud in yours... purge your bottles if different ones are better. Replace the thermocouple.

Next to Last perform an exorcism.
Last get a new furnace.

[Bill M.]

Ours needed a new gas hose between the regulator and the copper lines. The furnace worked fine on the tailgate of the service truck, but not in the trailer. Previously had a couple of bad thermostats. With those the furnace worked in the shop but not in the trailer.

[strangepod]

What others are saying (you won't have a thermocouple) - you will have a flame or sail (same thing) sensor, could be dirty. Also since the electronics are 15 years old and next to a HOT box, it is possible to have bad/cracked solder connections causing this.


John

[azflycaster]

Originally Posted by Sdt

Sometimes the furnace will work and even not moving the next morning it won't. Been to the repair shop twice and they think it's fixed. Maybe a loose connection. It works for a few times, then it doesn't. Any one else have problems like this?

Mine had a similar issue which I finally resolved. The symptoms when it fails and the error code generated will help in problem determination and repair. One of the most common failures is caused by the sail switch not closing which produces a blink led once and repeating. Ignition problems and detecting ignition (my error) will try 3 times and produce a blinking 3 times led and repeat.

My furnace worked on dry days and always failed when raining. The ignightor was the failing component.

[GCinSC2]

Sdt,

Can you identify the make and model of your furnace? Have you looked for fault codes yourself when it fails?

Gary

[tjdonahoe]

Our furnace has has spells when it wouldn’t come on....when I switch tanks...I was told to open the valve very slowly....wow no more furnace problems....it was the safety valve operation....all is well..open very slow

[vhaalen]

We had same problem, got worse until it wouldn't ignite at all. Shop replaced burner and showed me old one, which was pretty much disintegrated.

[Sdt]

I should have been clearer, when you click on the thermostat, the fan should kick on first then furnace ignites. My problem is that sporadically the fan will not kick on. Repair shop twice thought maybe loose connection as it began working while they worked on it. I thought maybe thermostat but it checked ok. Someone said it may be a bad electronic board?

[Tim A.]

We have had similar problems with our furnace over the years. All is well now, after: replacing board with one from Dinosaur, installing a sail switch which functions, and replacing a malfunctioning propane regulator. Those things were not all done at the same time. Each solved a particular problem.

Tim

[chugchug]

Had the same symptoms as you. Turned out to be lint in the sale switch.

[Proton]

e ignites readily in the mornI have a Bambi, but same problem. Checked everything, but the thermostat switch. Realized that is was the cheap thermostat switch which is spring steel not making contact. Remove the cover from the thermostat and push on the contact points with an insulated screw driver. See if the fan engages and ultimately the heater. You could also check your gas line pressure by seeing if the stoving.

[rs52]

I had the same problem. Turn the thermostat up and ... nothing. I’ve changed the board for other reasons twice, including a Dinosaur, and this intermittent failure occasionally rears it’s head. With mine, I can alway get is started Fonzie style with a rap on the outside access panel or a heavy step in the galley near the furnace. Obviously a loose connection somewhere but have not been able to track it down. One service guy thought it was a bad ground.

[GCinSC2]

This was a fix that worked on my Atwood furnace.

It would try to cycle then stop never firing up. IIRC it lit a fault code light too.

One time when it was trying to start and I had the outside cover open I jiggled a wire or two and away it went.

Pretty sure I wound up removing two scotch lock type wire taps and rewiring to make direct connections.

This is a fast non permanent way to take an existing wire A-B and in its run tap wire C onto AB without making independent connections.

That’s why I was asking for make model info.

[A W Warn]

Originally Posted by Sdt

I should have been clearer, when you click on the thermostat, the fan should kick on first then furnace ignites. My problem is that sporadically the fan will not kick on. Repair shop twice thought maybe loose connection as it began working while they worked on it. I thought maybe thermostat but it checked ok. Someone said it may be a bad electronic board?

If you have had a competent person check out the furnace they should have ruled out the sail switch not operating properly, the burner or exhaust being blocked or leaking, the igniter and flame sensor malfunctioning, and/or the gas solenoid valve not working.

I would ask if they checked the internal high temperature safety switch for continuity under load. If they did, I would suspect the circuit board is bad.

If you purchase a new board, spend a few $ more for the Dinosaur board, it is much more reliable.

ps:
Assuming you have a heating, furnace only, single function thermostat (do not have a heat pump/AC that uses the Comfort Control Center thermostat) you can check to see if the thermostat is malfunctioning. There are two blue wires connected to the back of the thermostat that control the furnace. (these blue wires are not at the thermostat if you have the CCC, they are in the rooftop unit at that control board) Touching those two wires together should activate the furnace. If touching those two wires together makes the furnace run when otherwise it will not, that proves that the thermostat is bad.

[bradt]

I have a 2007 Safari and once the furnace quit running. I found a problem with the connectors that just clip on various colored wires around the control board. The clip on connectors are supposed to pierce the insulation and contact the wire (insulation displacement). They used them to make T connections. Over the years the plastic wire insulation had shrunk, so there wasn't enough force on the piercing points to make contact. They look ok, and sometimes work, but other times don't. I could repeat the problem by slightly moving the wires around. I just cut & stripped the wires and used a wirenut to connect the 3 wires making up the original T joint. Has worked fine ever since. Hope this helps!
Regards,
Brad

[blkmagikca]

I had a similar problem about 2 years ago. I had replaced the original furnace. For a short while, it all worked well, then it worked intermittantly. Ultimately the last repair place reached in alongside the furnace and grasped the bundle of wires while the furnace was not working, but the thermostat was set to max. The furnace blower came on; but when he moved the bundle of wires an inch to the left, it stopped. The issue was the connectors on the wires for the power and thermostat - they needed to be pinched to snug them down.

[bartzstream2]

Originally Posted by vhaalen

We had same problem, got worse until it wouldn't ignite at all. Shop replaced burner and showed me old one, which was pretty much disintegrated.

If a guy is even a bit mechanically inclined, replacing suspect parts is pretty simple, and videos are available for guidance. The burner is sort of a flame diffuser and they will rust away and likely not allow the flame to be correct. You should be able to hear the ignition of the propane after about 15 seconds of the fan operating on startup to purge any potential propane fumes from the combustion chamber. You can remove the 2 fan wheels, the smaller of which delivers combustion air to the combustion chamber and the larger of which circulates the (soon-to-be) heated air through the ducting. These squirrel cage fans need to be clean to move the proper amount of air, whichever their area of responsibility. If you do not hear the ignition, take a look at the burner, and the electrical connections (for corrosion or loose connections) for the solenoid that operates the gas valves. As other commenters have noted, the sail switch needs to be moved by the air flow from the circulatory squirrel cage in order to allow the gas valve to admit propane to the process. Dirty cages may hamper that, or the switch itself could be bad and can be tested with an ohm meter. A DC volt meter will give you a reading on the battery voltage, and if it is too low, the squirrel cage will not move enough air to allow the sail switch to do its job. Hope this helps. As an aside, there is a master switch inside the exterior furnace door that cuts power to the unit for service. The furnace operated exclusive on DC power, so there is little chance for injury (electrocution) when working on it. The master board could be defective, and I believe it has some diagnostic LEDs on it. Replace it with the appropriate Dinosaur board. It just plugs in, a very simple install.

[LAWBC]

Originally Posted by Sdt

Sometimes the furnace will work and even not moving the next morning it won't. Been to the repair shop twice and they think it's fixed. Maybe a loose connection. It works for a few times, then it doesn't. Any one else have problems like this?

Had a problem with furnace which ran intermittently and finally stopped heating. The igniter's insulator was cracked(made of ceramic ) causing a electrical short so the furnace and so could not fire up.

You could hear the clicking or attempt to fire and the fan running but no burner running.