York 90 Gas Furnace no heat during cold snaps

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Old 01-17-09, 08:47 AM
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York 90 Gas Furnace no heat during cold snaps

Okay, so my wife verified that the heat was working when she got home yesterday. This morning we woke up to the same thing. I am down near the unit I hear it turn on. Run for about 10 minutes, turn off and then repeat the cycle.

So the sequence of events is as follows:
-Set thermostat to 71
-fan turns on in furnace
-after a minute of running the igniter lights
-the burners get lit
-the main blower turns on and the unit starts to (try to) heat the house
-after about a minute of the flames being on the burner goes out
-the blower continues to run for a while, eventually blowing cool air
-blower shuts off and the cycle starts over again


My main question is why does our furnace only do this when the temp is below 20F or so. It has been working fine for the rest of winter.

York Diamond 90
P2URD12N07501A

Propane tank is 500gal. Not sure about the line sizes.

Hmm it seems now it is actually trying to heat the house properly, sigh I wish I knew what was wrong with it.
 
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Old 01-17-09, 09:18 AM
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I just looked at the bottom compartment, where the control board is. I think there is supposed to be a light, but I couldn't find it. There is a trip switch that turns the whole system off when the cover is removed. So I buttoned her back up since she seemed to be working (at the moment anyways).
 
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Old 01-17-09, 09:25 AM
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Glad you started a new thread. The last one got so convoluted with folks jumping in with their own heating problems it was impossible to follow. Just to get a few things clear.
  • Is the P2URD12N07501A a condensing furnace, i.e. does it use PVC plastic pipe for the flue?
  • Does the furnace have a LED light on it's control board or module? If so how many times does the LED blink when the malfunction occurres?
  • IS your propane tank full and have you had the pressure checked?
 
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Old 01-17-09, 09:33 AM
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Yeah PVC for the flue. I couldn't find a led on the control board. There is a power trip switch that removes the power when I remove the cover for the bottom half where the board is. There looks like there is a little window but it is pretty foggy. I put the cover back on as the unit is currently working.

I haven't had the pressure checked explicitly. Amerigas filled her up (about 387 gal) in November or December.
 
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Old 01-17-09, 09:39 AM
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Originally Posted by diamond.g View Post
I just looked at the bottom compartment, where the control board is. I think there is supposed to be a light, but I couldn't find it. There is a trip switch that turns the whole system off when the cover is removed. So I buttoned her back up since she seemed to be working (at the moment anyways).
The LED should be on the circuit board. When this is the case there usually is a sight glass in the blower compartment cover so you can see the fault code but the wire harness may be in the way.

Use duct tape or some other means to defeat the door switch so it stays closed with the door off. If there is a LED on the board you should be able to see it. Newer furnaces usually have a two color led that flashes green if everything is OK and red if there is a fault. Yours may only flash when there is a fault so this may take some patience on your part. It may flash once when power is cycled. Do not leave the door off the furnace and leave the furnace unattended. This is potentially dangerous.
Do this as a troubleshooting measure only do not leave the tape on the door switch.
 
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Old 01-17-09, 09:47 AM
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I removed the little cover that I think I am supposed to see through. Turned the heat up to get the system to turn on. Saw no led lit at all. I did leave the cover on so I can walk away though I will check back a little bit later and let you guys know if any codes pop up.
 
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Old 01-17-09, 12:55 PM
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Nothing so far, hopefully the weather doesn't dip as low as it did last night. I will post any updates.
 
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Old 01-20-09, 09:39 AM
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I'm wondering when the weather gets bitterly cold, the propane is having problems volatizing, and the gas pressure drops off until finally the flame goes out? The other thing that could be wrong would be the flame sensor being dirty, but if the flames burn for a whole minute before they go out, and the burn properly in warmer weather, then that doesn't sound like flame sensor problems.

I'd have the propane company check the regulators to see if possibly they are freezing up or if the pressure is on the low side. It sure sounds like you're losing gas pressure when it gets really cold outdoors.
 
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Old 01-20-09, 09:57 AM
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Personally I wouldn't be too suspicious of the propane gas supply. A 500 gallon tank is a reasonably generous size, and the furnace is gutting off rapidly. A 500 gallon tank suggests a tank that was sized by someone who probably knew what they were doing. Could be the problem, but that wouldn't be my prime suspicion.


diamond, the reason you have been asked about diagnotic lights is that they greatly simplify diagnosing a furnace problem, especially for do it yourselfers. And unfortunately I haven't been able to find a circuit diagram or installation manual by looking about on the internet, so at least for right now you have to do some furnace testing to help identify the problem.

Please provide the make and model of the ignition control module for the furnace, which often has the wires to the thermostat running to it.

Do you have a multimeter for testing voltages and resistance and understand how to use it?
 
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Old 01-27-09, 07:35 AM
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Originally Posted by SeattlePioneer View Post
Personally I wouldn't be too suspicious of the propane gas supply. A 500 gallon tank is a reasonably generous size, and the furnace is gutting off rapidly. A 500 gallon tank suggests a tank that was sized by someone who probably knew what they were doing. Could be the problem, but that wouldn't be my prime suspicion.


diamond, the reason you have been asked about diagnotic lights is that they greatly simplify diagnosing a furnace problem, especially for do it yourselfers. And unfortunately I haven't been able to find a circuit diagram or installation manual by looking about on the internet, so at least for right now you have to do some furnace testing to help identify the problem.

Please provide the make and model of the ignition control module for the furnace, which often has the wires to the thermostat running to it.

Do you have a multimeter for testing voltages and resistance and understand how to use it?
I have a multimeter, and I do know how to use it. I have been checking up on the furnace, there appear to be no leds on it. I will look for the model number of the items you requested (when I get home) and post them.
 
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Old 01-27-09, 02:28 PM
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Originally Posted by diamond.g View Post
I have a multimeter, and I do know how to use it. I have been checking up on the furnace, there appear to be no leds on it. I will look for the model number of the items you requested (when I get home) and post them.
The Control Board model number is G951ADB-1403. The good news is I found the led. It was Zip tied in a bundle, which is probably why i couldn't see it light up.

So when you first put the cover back on (and the unit notices it has power) the led flashes once (quickly). So when the burners go out it flashes 4 times pauses for about 10 seconds then flashes 4 times again (this repeats a few times) then the unit relights the burners.

The 4 flashes is the hi temp limit right?
 
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Old 01-27-09, 02:51 PM
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Unfortunately, this control doesn't appear to be manufactured any more, although other modules can be substituted for it. But I can't find any instruction manual describing it operation in detail.

It is for a hot surface ignition system.

If you look around the furnace, you may find a list of codes to use to interpret the LED blink codes. If you find such a list, what is the problem identified by the four blinks? I can't tell if your comment about the limit switch was a guess or a report on the code you found.

I'd be more suspicious of the pressure switch shutting off the furnace than the limit switch. It typically takes longer than a minute for the furnace to overheat and shut the limit switch off, especially since you report the fan turns on in your opening post.

But what the heck --- check both the pressure switch and limit switch to see if they are opening when the burners shut off. By setting your multimeter to measure more than 24 VAC (50, 100 whatever) and grounding one test lead, check both sides of these switches. if you have 24VAC to both sides of the switch, it is closed and operating properly. If only one side has voltage, the switch is open.

The pressure switch will only close when the inducer motor is operating.
 
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Old 01-27-09, 05:38 PM
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okay, I can't seem to find a led code list. But I did put my multimeter to the Pressure Switch (apparantly I have one for the condensate 2LP and one for the burner box/ventor 1LP) White lead (this probably doesn't help but it is from the limit switch according to the diagram) goes into 1LP then a black wire goes to 2LP. A blue wire then goes to the control board. Neither wire has power when the flame goes out. Neither does the gas valve, nor does the limit switch.

I took the limit switch out to take a look at it. Not only are the connectors rusted on (stuck) but the piece at the end had some rust on it as well.
 
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Old 01-27-09, 06:12 PM
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If the limit switch goes out, what will happen is the supply side to the limit switch will still have 24 volts, but the outgoing wire will not, since the limit opened up(stopped working). Then when THAT happens, it stops current flow downstream to ALL wires on the pressure switch. That then would be the tip off it is not the pressure switch, but the limit switch instead, since you would have 24VAC power INTO it, but not OUT of it.
 
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Old 01-27-09, 06:25 PM
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So the white wires wouldn't have power but the red wire should. Now is it supposed to have power even when the furnace isn't actively running?
 
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Old 01-27-09, 08:23 PM
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Since you can't find the diagnostic codes, was your earlier post about the four blinks being a pressure switch problem simply a guess?

I take it the correct answer is that you just don't know.

Guesses are OK if they are labaled as such. But it's important not to mislead someone who may be trying to help you with a guess.
 
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Old 01-28-09, 04:55 AM
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Originally Posted by SeattlePioneer View Post
Since you can't find the diagnostic codes, was your earlier post about the four blinks being a pressure switch problem simply a guess?

I take it the correct answer is that you just don't know.

Guesses are OK if they are labaled as such. But it's important not to mislead someone who may be trying to help you with a guess.
Sorry if I was misleading. Yes it was a guess.
 
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Old 01-28-09, 10:19 AM
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Frankly, I can't find enough information about the furnace to be of much help to you. With multiple pressure switches and no way to interpret the diagnostic lights, I don't have much confidence that I can point you in the right direction.

Perhaps Ecman will have some better ideas, or someone else.
 
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Old 01-28-09, 02:49 PM
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No Problem. Thanks for all the help you all have given thus far.
 
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Old 01-28-09, 05:33 PM
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Originally Posted by diamond.g View Post
So the white wires wouldn't have power but the red wire should. Now is it supposed to have power even when the furnace isn't actively running?
Colors do no help me. Just tell me the number of wires that go to each part in question that we have been discussing, and that would suffice.
 
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Old 02-08-10, 08:21 AM
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Sorry for the long no reply, the furnace was actually working fine, but with the snow that we just got along with the loss of power and the house being super cold (47) I noted that the problem has sorta returned. I finally was able to take pictures of the furnace I am just going to link the gallery since the pictures are not cropped.
My furnace photos
 
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Old 02-08-10, 08:24 AM
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I can take more pictures if there is something you guys need to see. They would be added to the original link.
 
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Old 02-08-10, 04:38 PM
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Noob post alert!:

You didn't by chance check to see if the outside air intake for the furnace was blocked with ice or something? That happened to me once. When it would get cold, the combo exhaust/in take would freeze due to condensation because of a poor fitting. A little silicone and I never had a problem since. Also have seen ice freeze up to the exhaust pipe as well.
 
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Old 02-08-10, 05:45 PM
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Tolyn suggests something that is typical in snow country.
Always worth checking. In fact, reputable HVAC companies may tell you to check that before even sending a man out. And I actually found a plastic grocery bag had started to get sucked into a PVC intake pipe, causing the furnace to shut down, last year! On another rental, college students buried the exhaust pipe when shoveling!

But after reading your first post again, and then the subsequent posts and replies, it sounds classic pressure switch or other safety circuit failure. Usually when what Tolyn suggests occurs, there is no igniton at all, because the pressure switch is "open" from the get-go, due to poor drafting. But yours does fire up, but goes out in about a minute. That is usually a sign of something going out on the 24 volt saftety circuit - that includes the limit switch, roll out switch(es) and pressure switch(es).

See if when the flire goes prematurely out(meaning the fire went out, but yet there is still a verifiable call for heat, and the inducer is still running) -to see if you have 24 volts entering and leaving the pressure switch.
 
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Old 02-08-10, 08:27 PM
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Another thought: Try setting your thermostat fan to "on" instead of auto. I had a friend who's furnace would do what yours is doing (after I reread your post). For some odd reason the circ fan would not kick in when the stat is set to "auto".
 
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