Furnace Tries 2 or 3 times before staying on until reaching set temperature


This is not really an answer, since I don't think this can be answered without being on site. Rather, I'm going to explain a bit about how the system works, and offer a few ideas as to what the problem could be.

To start, you'll want to understand how air moves through the system. You'll want to know the difference between conditioned air, and combustion air. And you'll want to understand the normal ignition sequence of the unit.

Combustion Air

Combustion air, is the air the furnace uses to burn fuel. As you may know, fire requires heat, fuel, and oxygen (oxidizing agent).


Heat is typically supplied using a hot surface igniter, spark gap, and/or a pilot light.


In this case, fuel is natural gas.


Oxygen comes by way of combustion air. In this case, the inducer draws air into the combustion chamber, and expels it out through the exhaust vent.

Conditioned Air

Conditioned air, is the air...

0 0

Sounds like either a bad over-temp switch, or cause for an over-temp. Replace the plenums over temp sensor, or remove obstructions from the air system (dirty coil or filter, closed registers, half detached and now hanging duct insulation.) If all else fails cut the gas back some by slightly closing the gas valve, however be prepared to have to reset the furnace if your local gas pressure drops intermittently. My step one on Goodmans is as mentioned, clean the flame sensor, but I think they only run for a few seconds if that's the case.

"Sometimes there's no flame at all" sounds like a bad pressure switch on the exhaust blower. Until that switch is satisfied the gas valve won't open. But you must be sure it's not still in a lock-out. This applies to only when you do a cold start (flip the switch that should be there, or the...

0 0

Bottom line the thermostat controls the off and on of your heat system thermostat is nothing but a switch that shuts your furnace on or off when the desired heat level is reached, you can actually run a heat system manually with a simple toggle switch and get the same results as a thermostat, so to simplify your problem first make sure your power supply to the furnace is correct if so then remove the cover from the thermostat and place a jumper wire from the red terminal to the white terminal or green is your fan yellow is your air condition if nothing starts when you touch all three terminals then you need to check the transformer voltage it should read 24 to 26 volts, if this checks out and still no function then you have other problems and it may require a trained tech.to trouble shoot as it could be a combination of many things, there is no simple one solution to any heat system every problem must be considered, in plain English no one can fix your furnace with one simple...

0 0
Hello, this is my first post, so please be kind.

I have an Amana Furnace model AMV9- 0905DX-B two-stage variable-speed gas furnace, 90,000 MBTU/h, 90% AFUE.

I recently replaced the main Board and the Inducer Motor because for a few days, my HVAC technician had to spin the motor wheel manually as it was not inducing enough draft to ignite the 4 burners. He made sure to grease the motor very well, and that seemed to get things going while the parts arrived. He claimed that the parts were back-ordered and there was no way to know when they would arrive. He then claimed that I may wish to replace the furnace, which would guarantee to be replaced the following day (obviously a sales pitch, since my furnace is less than 7 years old).

Annoyed with such attitude, I proceeded to order the parts myself and replaced them (saving me about $1,200 in the process, or even more if I would have replaced the entire furnace). I made sure to map every single thermostat and other wire to...

0 0

Answer Yes, the thermostat in your home causes the gas valve to come on inside the furnace, although in some of the newer, high efficiency furnaces the process is

… a little more complicated. Furnaces usually detect the temprature inside the plenum and turn on the blower to move warm air into the home. Once the home is up to temperature, the gas is shut off and the blower will run until the plenum is cooled. Answer The gas should not go off and on until it reaches the desired temperature. The gas should come on and the burners should stay lit until the desired temperature is reached. If this is not the case and the burners come on and off, you have a problem. If the burners come on and stay on until the temp set on your thermostat is reached then all is well. If you notice your burners are not lit and the temp is not reached and the blower is on, then you have a problem that needs a service tech. Your filter could be clogged or your flue pipe could be blocked or...
0 0

We have lived in our current home for almost 30 years. For the first 22 years or so, we made do with the 1970's vintage NG furnace. It had the habit of regularly having to restart before the house was fully heated in the morning. By restart, I mean the programmable thermostat would call for heat, the unit would turn on, but before reaching the set point it would cycle off, then immediately restart.

I thought that was odd, and tried a couple of different thermostats over the years. The last being a Nest, which detected this condition and admonished me for being a bad furnace owner and neglecting it in some way. We've always been regular with the filter changes, and that older furnace had little to nothing in the way of pressure sensors... why should it? It was old school.

Fast forward to 2012, when we pulled the trigger on a new Day and Night N9MSE. Imagine my amazement when it immediately continued with the series of restarts (usually 3 starts were needed to heat...

0 0

Start >>

Every two years the Amana GUIC-070 furnace in my house starts acting up. Sometimes, when the thermostat "calls for heat", the burner will ignite and then go out within a few seconds. The ignition control module will try to start the furnace again, and the burner might stay lit for the normal duration. Over a period of a few months the situation degrades to the point where almost every time the furnace tries to start, the flame goes out within 5 seconds.

On this furnace, the problem is the flame sensor... it develops a thin coating of clear or whitish deposits that insulate the sensor from the flame, so the ignition control module doesn't receive the signal that the flame is actually lit. Without that signal, the control module shuts off the gas valve and then tries starting the furnace again. If 3 to 5 attempts don't succeed in lighting the flame, the control module will wait for one hour and then try again. That's an hour where the house has no heat, and if...

0 0

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Furnace turns on after call for heat has been satisfied:

This article describes what to check if the warm air heating blower fan cycles on and off after the call for heat has stopped, that is after the room thermostat has been satisfied.

Some conditions that cause unexpected furnace fan cycling on and off may be dangerous, risking overheating of the furnace heat exchanger which in turn risks cracks and even carbon monoxide leaks. So it is worth checking out this problem promptly.

Green links show where you are. © Copyright 2017 InspectApedia.com, All Rights Reserved.

How to Diagnose & Fix a Blower Fan That Keeps Cycling On/Off After Call for Heat Has Stopped

Why does the blower fan keep turning on and off repeatedly after the thermostat has stopped calling for heat?

What do you do if the...

0 0

Furnace starts, then shuts off.

Rheem Criterion model.

It begins its power-on cycle normally. First the updraft blower turns on for a bit, then the HSI glows bright orange, then the gas turns on and the flames ignite fully and the big blower turns on.
About 3 seconds after the gas ignites, it shuts off. That is the gas shuts off, the blower continues for about a minute then it shuts off. This cycle will repeat a few times, then usually after the second or third time everything stays on and works normally.

Is there some kind of flame sensor I can check/clean/replace?
Anything else?

Would any pics be of help?

Last work done was the HSI was replaced two years ago.

How long is it after the big blower cuts on that the gas shuts off?

to dm19891

My guess would be that the pressure switch is opening.

It may not necessarily be faulty, there could be an underlying cause. When the blower kicks on, it's pulling vacuum or...

0 0