Hi All, I have been having heater furnace problems for a while now with this Day and Night furnace. I was hoping if any one can help me further troubleshoot this problem before the fall/winter comes. Thanks in advance

The Model information:
Carrier BDP, Day and Night furnace, model number 376BAW036055AABA, Natural Gas, Horizontal downward


A while back ago the heater broke and the only the blower continues to run when power is plugged in for the heater furnace. From reading these forums and thanks to all the posters here, I was able to trace that one of the fusible links were broken (no AC voltage reading between R and C) I ordered the part and replace one of the fusible link and was able to get pass the "continuously blower fan" problem. Now, I check the R and C connection and it is reading about 26.7 VAC. I also check that the Transformer Sec 1 and Sec 2 and it measure about 26 VAC as well.

Now when I plug in the heater, nothing happens until I turn the themostat to call for heat which then the inducer fan (I believe its call) turns on. But I don't see the pilot light come up or hear any loud clicking noise. The inducer fan continues to runs. My question is how do I further isolate the problem to see if its the spark ignition generator problem or is the the gas regulator issue. There is a solid state spark generator that is label with T1 and T2, should I check there?

Any advice on where should I check?

I have attach a picture of the furnace, the right side is where the gas regulator with the black box in the middle being the spark generator.

Thanks,
Peter

 

Is the orientation of your picture correct ?

What fusible link did you replace and did you find out why it blew out or opened ?

At the present time it sound like you have an issue with the inducer not creating the proper draft. The two problems may have been related.

 

I'm really curious, I am not familiar with day night furnaces. Is that a fan I am seeing on the left, lower side of the pic. Could you get a wider pic, so I can see the flue. Do you have any paper work on the furnace?

Now to your question, there should be a tube coming off the inducer fan. Make sure there aren't any cracks in it and check to make sure it isn't blocked up.

 

Here are some more pictures the furnace in a wider shot, all pictures are in the correct orientation as I see it inside the attic.

As for the fusible link, I replace the one label no I was not exact sure what cause it to burn out. Our house did experience a high voltage surge several months ago that knock out my fridge controller board and dishwasher when the car accident hit a power pole. It was around the same time that I notice the heater furnace broke but again I'm not totally sure since I did not use the heater right away back then.

I will add more pictures on next reply.

 

Since I can't find the manual for your furnace...that schematic picture is semi helpful. It looks there are several safety stats as well as the pressure switch in the orange line. You'd need to check for something open.

The pressure switch, next to that fan, should be open until the draft inducer is running and then it should be closed.

 

Hi PJMax, thanks for the response, however can you be more specific on where I should look or measure for open or short. I can't seem to find any place to check for open.

By the way, I ran the heater for about 15 mins and it still just the inducer fan running when I turn the thermostat for heat

I attached both the connection diagram and the schematic on the photo sharing site flickr

https://www.flickr.com/photos/958521...7644995884092/

 

Thanks to all whom replied, I was able to find that the pressure switch was not closing when the inducer fan is running. I check the vent pipe and there were no debris clogging the pipe.

So with that precaution check out, I went ahead and perform few simple tests to check out the pressure switch to see if thats root problem causing the no ignition. The pressure switch is a 0.35 inWC with 3 terminal type labeled "COM", "NO" and "NC".

With a ohmmeter with no power apply to heater furnace and wiring disconnect to the Pressure switch, I measure COM to NC is close to 0 ohms and COM to NO is open circuit. I put the wires back (Orange, Brown, and Yellow) to the pressure switch terminal and plug power back in the furnace and issue call for heat. The inducer fan start to run and I measure 24 VAC from ground for COM and 24 VAC for NC. The pressure switch does not toggle over to the "NO" and it measure 0 VAC. Next I took off the pressure switch tube and blow into it and it was still not closing.

At this point, I was think that the pressure switch was the issue so I make another test and jumper COM to NO emulating the pressure switch. The procedure I follow is first jumper COM to NC and issue call for heat, then the inducer fan starts to run. Then about 5 sec after, I jumper COM to NO in hopes that it will fire up the pilot and get heat. I did that and nothing happens other then the inducer fan keeps running.

Can anyone offer any other advice on where else I can look, is my troubleshooting technique of the pressure switch correct?

Thanks in advance to everyone

 

Anyone have any recommendation or advice, I'm really stuck right now and don't have much to go on.

I do have a new update, I did try to clean the little air hole from the inducer fan to tubing to the pressure switch. After that I did notice that I was getting 24VAC to Gnd from the Normally Open (NO) terminal (this pressure switch has three terminal: COM, NC, and NO), but I also got 24VAC across NO as well.. which puzzle me even further.

The pressure switch connects to a circuit card, Hamilton Test System HH84AA007, model 990-490.

Thanks in advance,