Furnace not coming on when it should

From all that has been said and diagnosed, I'd say that the "time delay relay" located in the furnace compartment is the culprit. It is supposed to delay the start-p of the furnace to insure among other things that ALL combustion gases have been purged brfore reigniting. I'ts a $40.00- $50.00 dollar part and is a quick replacement. You could do it yourself as it is usually easily accessiile. Spounds like your somewhat in a fixed location which means that a service call will be needed if you choose not to DIY.

Are you sure there is no sensor....it is a small 1" x 2" plastic thing on the wall in our bedroom. Bedroom is 3-5 degrees colder than up front area where the stat is located......especially when the door is closed.

We don't have anything but the remote. I need to buy a room thermometer to get numbers before we go any further.

We have a Suburban furnace with the usual 4 or 5 button stat. There is a sensor in the bedroom that tells the stat how things are in relation to the stat's setting. Any clue here ?

sounds like something is out of calibration
might need a sensor or some part replaced

until then just change your settings the amount you need to get the temps you desire

Sorry. Been too busy with other problems to get back before now.

Yes, I have a Carriere A/C unit. I have a Surburban furnace on the ground floor. Yes, I have a remote which manages A/C, heating, Fan, and something else I can't remember. The green light indicates something has been set by the remote.

The furnace does work, but for example, we went out this evening, leaving the remote temp set at 66F. By the time we got back in the late evening, I'd say the inside temp was in the 50F range (it gets cold at night in AZ !)

So I cranked up the remote to 75F. Nothing happened. I directed the remote to the ceiling A/C area and turned the remote/furnace OFF. I then pointed it again and clicked the button on the remote to turn the furnace on. It came on, and started to heat the trailer. As it was working, I set the temp on the remote to 66F and I'd say it did go off at about that temp after 10 mins or so.

Notice to turn the actual REMOTE off, you have too point it to the floor, and click the OFF button.

Now we have noticed that if we leave it at 61F for the night, our usual practice, the furnace does come on and go off a couple of times.

It seems that the furnace will only turn on, when it is a long way below what you have set it to turn on. Or when I turn the upper temp way above what it is now.

Does this help in your diagnosis as to why it's not coming on when the temperature drops below what we have set it ? Thanks for suggestions

Sounds like he may have a roof air conditioner with electric heating element?

Steve

Every time I have a problem with a furnace in an RV it is from dirt in the burner.

The Green LIght in the roof????? Do you have a carrier AirV air conditioners?
Otherwise the furnace is normally located at floor level not roof. nothing on the roof or in the roof should matter.

Now the Carrier (And I have no doubt some others) uses a I/R remote and teh thermostat is in the air conditioner housing. This one has lights in the "Roof" to indicate some things like 120vac is present and 12vdc as well. But that's about all (or and an error indicator for the A/C).

The furnace is controlled by a relay.. ON/OFF like a toggle switch but operated by the A/C control system. Mine is gone.

So I now have an advanced Furnace control system.. It helps seriously
IT consists of a Toggle switch.. a common Mechenical wall thermostat of the mercury free type. an LED (indicates with the switch is on) and resistor (To protect the LED)

WHat did it show... it showed that I had a short in the blower motor system. Still have not tracked it down but I know what to do about it.

How the furnace works
T-Stat calls for heat
Control board starts the blower
When air flow is strong enough the sail switch sails and signals the control board which then opens the gas valve and starts sparking to fire it up.
After a brief period of sparking (NOTE THIS is the single wire ignition system) the control switches to SENSE mode looking for just under 1/2 volt (0.480) on the same wire that a fraction of a second ago had about 1,000 volts on it. (WOW)

the multi-wire systems sense all the time. and use a different wire for SPARK.

IF flame is sensed (0.480 volt) then the burner continues operation till the T-Stat says "Warm enough" then the burner shuts down. blower continues a bit then it shuts down.

Possible issues include many logical things but what happens if the change from SPARK to SENSE goes at the wrong time and the SENSE chip gets socked with 1000 volt spark voltage.... Pop goes the sensor.

DINOSAUR Boards put a over voltage arrester on teh board Atwood did not.

Bad remote