fraser-johnston nateralgas model#pdsd-ld11n100a

[needanswers]

this unit last year twice came on and only the fan worked. Both times I turned off then turned back on and it worked fine. This year I tried it and the same thing happened, except I could not get it to work at all. That was a week ago, today I tried it again and it worked for 5 minutes, than stopped. No matter how much I turned the temp up nothing, not even the fan came on. Does this sound like something anyone out there has ever heard of? Can anyone tell me how to fix it? I do not have the money to pay someone to fix it, and I am mechanically incline. I have to be if my family will have heat this winter.

[hvacdrd]

Since service manuals for some makes are harder to come by than others lets start with a few basic questions.

1-does this have electronic ignition

2-does the furnace have an exhaust fan - do you know if it is an 80%(metal vent) or 90%(PVC vent)

3-do you have A/C - if so does the fan come on when tstat fan switch is set to ON

4-when you turn on the heat do you hear anything at the furnace or see any flashing diagnostic lights

5-thermostat - is it mechanical(dial or lever) or digital

6-do you have a volt-meter

[needanswers]

It has a digital thermostat, that works with the central air, and you can run the fan by it's self.

It has an electronic ignition.

When I turned on heat last week everything sounded like it was working except it was like no gas was getting to the igniter. Yesterday I turned it on and I heard the clicking of the igniter like last week and I heard the gas (which I didn't here last week) and it lit, but after 5 minutes it shut off, and I can't get it to make any noise. I can still run fan, thats it. The thermostat works to put on the AC, but except for the therostat making the noise it is turning on heat, when I go out to heater it makes No noise.

I do have a vote meter.

[Pegi]

Vote Meter>>??? 

I know nothing about central heat systems, however when mine was having problems last winter it would do the same things you are describing...I called it "short cycling" erraticly at different places in the ignition sequence..would stop after the exhaust fan came on, after the delay the fan would come on, then the burner but cut back off, after another delay it would get to the burner on and the fan running to blow the heat into the house, then the next time who knows....now mine is a carrier I believe and the repair company found cracks on the circuit board that runs the system, and I do not know if you have a board or not....this is something I thought about after reading this thread as it may help or not...

[dkpd1581]

If you have a combustion fan motor that runs and pulls air into the burners and forces the flue gas up the flue pipe, you may have an obstruction there.  Typically a unit will run for a few minutes until the flue gas backs up and either causes the heat to build up in the flue and trip out an over temp sensor or the flue gas builds up and then the pressure proving switch does not have enough pressure to make the safety circuit and then cuts the machine off.

I tried for about two hours last night to find a manual online about your unit without luck.  You need to see if you have what is called a combination fan/limit switch.  It should be in the middle of the heat exchanger section and have a metal cover.  If you take the cover off, it will have a silver raound dial in the middle and also 3 tiny metal pins.  These pins let you set the temperature that the fan starts, stops, and trips out at.  With the heater running you need to watch the face of the silver dial and see that it starts to spin very slowly as the heat in the exchanger rises.  If the dial spins to the point where the 3rd pin is reached (the over temperature setting), your blower may be on too low a speed, you may have an air flow issue, you may have a gas pressure problem that is over firing the burners, or your blower motor may be failing.

Unless we can see a diagram or a picture of the heating section, it will be hard to really help out.

[needanswers]

Right now I can not even get this unit to start up. before 2 days ago it would attempt to come on, but not lite. Then 2 days ago it came on for 5 minutes and shut off and now does not do anything. The thermostat clicks on in my hallway, I go outside to were the unit is and nothing. It is like no power is going to it. I have checked the fuses, and the breaker and everything is fine in that aspect. I don't know what else to check? I did not see a circuit board yesterday when I took the facing off the side. This is an old unit, I think it from 1989.

[applianceman18007260692]

http://americanhvacparts.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=fl-manualreset2wire

go to this site and look at them resetable safetys and that will give you an idea of what to look for

be sure to remove all cobwebs,birdnest,waspnests whathave you that may be blocking the vent

be sure to remove all the rust on all the burners, when they get rusty they tend to pool up gas in a certain spot and ignite in a POOF like manner,this causes the safetys to pop.

I have more. try this stuff first. if all the sfetys are ok then you may have a transformer gone out. keep us posted.

[needanswers]

I was in the heater, and found a loose connection, so the heat comes on. There is a kind of low boom when the gas lites. I was told by a friend that means the burner is dirty or bad. Is that correct? The website on last thread is good, but I can not find anything for Fraser-Johnston, do they still make them?

[AccApp]

F-J is now under the York umbrella which includes Coleman and United Products Group. Should be able to get most anything you could need. Can you post a pic of the burners? Some are real easy to clean and others are not.

[applianceman18007260692]

The burners can be blown out and wire brushed if they dont have any huge holes in them I have one of these wire wheels in my shop That is what I use to clean burners with. You want to make sure of even burning and ignition to the gas will not pool up and cause rollout or POOF !

wire wheel.bmp

[needanswers]

ok I  cleaned the burners and everything else, and they were pretty dirty. I have a new problem. In taking out the burners to clean I broke this wire that goes to the igniter. It was in bad shape, and it was almost broken to begin with, so I was being really careful, but not careful enough. I went on the website for parts, and looked for igniters, but couldn't find anything that looked like the part I broke. I saw a part that looked like the end that lites the the gas, but not the other end that is on this box connected to the gas line going into the furnace. What is that thing called so I can ask for the part or look for it in the website?

[applianceman18007260692]

lots of furnaces can be retrofitted with a generic part called a IG1000

[needanswers]

Well after all this time and giving what I thought was the right info, it turns out to need a mercury filled heat sensor. Thanks for all the info, even though I did not know what I was talking about I learned alot  from your help  thank you.  The parts website help very much. I called them and after 20 min on the phone they figured out what it was I was talking about.