Carrier Weathermaker 8000 mid-efficiency 58WAV upflow loss of flame

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Old 02-10-15, 01:44 PM
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Carrier Weathermaker 8000 mid-efficiency 58WAV upflow loss of flame

problem: flame cut-out in a continuing cycle, with duration of burner on time decreasing with each successive loss of flame

: no lock-out, cycle continuous
: code 31 after each burner out, LED returns to solid condition when ignition sequence restarts
: cycle stops with manual end of heat call at thermostat or power off to furnace
: normal ignition sequence and timing from inducer on, to blower on, for first three cycles
: burner on time, 8 minutes first cycle, 1 minute 2nd cycle, 15 seconds 3rd cycle at which point inducer stops and blower continues for 90 seconds (after each cycle)
: 4th cycle- flame out before blower starts, after ignition sequence
: 5th cycle - burner remains lit for 1 minute 15 seconds after ignition and blower on
: 6th cycle- flame out before blower starts, after ignition sequence
: 7th cycle- flame out before blower starts, after ignition sequence
: 8th cycle- same
: 9th cycle- same
: 10th cycle- same

: each time the burner flame stops, the inducer stops with it, and the blower will continue for 90 seconds before the ignition sequence re-starts.
: from troubleshooting of two furnace technicians, pressure switch, control board, and flame sensor have been replaced
: I have installed a new Honeywell thermostat and thermostat wiring

: code 31 sates that:31 PRESSURE, DRAFT SAFEGUARD, AUXILIARY-LIMIT (when used), OR
BLOCKED VENT SHUTOFF (when used) SWITCH DID NOT CLOSE OR
REOPENED - If open longer than five minutes, inducer shuts off for 15 minutes
before retry. Check for:
- Proper vent sizing and condensate pitch - Inadequate Combustion air supply.
or sag. - Low inducer voltage.
- Vent restriction or high winds. - Disconnected or obstructed
- Defective inducer motor or start capacitor. pressure tubing.
- Defective pressure switch or connections. If it opens after trial for ignition period,
blower will come on for 90 second recycle delay.

: new board- CES0110057-02, replaces CES0110057-00, updates include ‘furnace will recycle if pressure switch opens and re-closes during a call for heat’

: please help
 

Last edited by jackson4015; 02-10-15 at 02:08 PM.
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Old 02-10-15, 06:25 PM
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I would remove the hose from the barbed connector on the furnace and ream out the furnace end with a straightened paper clip.

Verify that the hose is not damaged.

It seems less likely that the vent pipe is restricted because that furnace should have a spill switch at the vent pipe connection with a manual reset button. If the problem persists You can look inside of the vent pipe for a wasp nest or a bird nest.

If I connected a manometer to the pressure switch tubing with a Tee, I would expect to see around .66 inches water column of negative pressure before flame with a .22"w.c. reduction in the vacuum when the furnace gets ignition and heats up.



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Last edited by Houston204; 02-10-15 at 06:46 PM.
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Old 02-10-15, 07:53 PM
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Thanks for your reply Houston204,

I've recently removed the hose and made certain it is clear and undamaged. The connection at the furnace end is a nipple, no barbed connector.

The switch at the vent pipe is exactly as shown in your accompanying picture and has never tripped.

I recently removed the vent pipe from the furnace to the first elbow and it was clear except for a white powdery build-up, which I cleared, at the bottom of that section of pipe and in the horizontal elbow at the top- it looked like calcification from some water infiltration, but not enough to create a blockage.

Of the various visits from furnace techs, I've yet to see one hook up a manometer. If one was hooked up as you describe, and showed an irregular reading from ignition to heat-up, along with the decreasing duration of burner on time and considering that the pressure switch is less than a year old, where would you go next?

This condition has been on-going with periods of normal furnace operation, but has degraded to the point it is at now, with virtually no lasting burner operation. Extreme cold, such as has been occurring here lately, does seem to make this problem worse, if not cause it altogether.

Again, thanks

I mention this in case it is meaningful: about 3 weeks ago, when this condition restarted, I found that if I left the burner compartment door off, the furnace would operate normally, but within minutes of replacing it, the flame would fail.
At this point, whether it is on or off makes no difference.
 

Last edited by jackson4015; 02-10-15 at 08:18 PM.
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Old 02-10-15, 09:01 PM
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Sadly, it is not very common for a serviceman to connect a manometer to a pressure switch with routine maintenance.

If one doesn't regularly connect a manometer to furnaces with routine maintenance it would be harder to know what to expect when it is measured.

I check the vacuum at the pressure switch, microfarad reading of the capacitor, and flame rectification with every heat check that I am able.

The wire connections to the furnace, gas connections at the furnace, ESP, Delta Tee, voltage,and amperage are also items that I check. I would imagine that most techs would also take these readings.
 
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Old 02-11-15, 04:53 AM
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I'll show the service tech your routine next time he comes for a service call and ask him if any of the checks have not been done.

Just from my own research and observations, I'm suspecting a problem with the inducer motor. Could you advise me as to what checks the technician could perform to assess the operation of the inducer.

Many thanks Houston204
 
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Old 02-11-15, 06:21 AM
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The induced draft motor squirrel cage can rust and fall apart.

Moisture can dry on the inside of the nipple on the furnace that feeds the pressure switch. It can seal the nipple much like a child's bubble wand and must be cleaned with something like a straitened paper clip.


The flame sensor should be cleaned.
5 microamps DC is a great reading but I usually read at least 3.5uA DC when I measure the flame rectification.

The run capacitor for the fan motor should read its rating plus or minus 10%.

The temperature rise across the furnace should be measured and compared to the acceptable range listed on the furnace nomenclature.
 
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Old 02-11-15, 11:09 AM
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This is all good, specific information- thanks.

I think I'll take the DIY approach to heart here, instead of relying on more technician testing for the moment.

I would have to remove the inducer to get a look at the squirrel cage and there is a gasket to seal the unit- when I put it or a new one back in its place, will hi-temp silicone be suitable? Is there any way to determine if the squirrel cage is damaged without removing the inducer? (it shakes, like it's out of balance when it's spinning)

The nipple I can check.

My tester has a low range of 200uA with resolution of 100nA- is this within the range I need to test the flame rectification, and how do I do this?

Where is the run capacitor and how do I test it?

The temperature rise is the difference between the air temp. taken where the duct leaves the furnace and the return air?

I appreciate your help with this problem.
 
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Old 02-11-15, 05:09 PM
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Houston seems to be tied up so I'll see what I can do to help. Honestly with the code & symptom list given, I don't think it's a flame sense issue. You will be toward the low end of your meter but with resolution of 0.1 microamp, you should be able to get a reasonable reading.

Personally, I'm suspecting either a draft or temperature issue. The guys you've been dealing with seem to be far from technicians, more like parts changers.
As for tesing the capacitor: Your meter will have to be able to read microfarads. Disconnect the leads from the capactior & put a probe on each terminal. Compare the reading to that on the cap.
 
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Old 02-11-15, 05:30 PM
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I usually remove the vent pipe to inspect the inducer squirrel cage.

It is easier for me to clean the nipple to the pressure switch tubing then to look inside for a restriction. ( but I own 2 manometers and measure the negative pressure)

To test the flame sensor, remove the (usually white) wire connecting the circuit board to the flame sensor an wire your meter in series with the flame sensor.
To do this I use an alligator connector on my black meter lead and connect my black lead to the flame sensor.

I plug my red lead to the white wire to the flame sensor.

After flame has occurred I read the meter on the micro amp dc scale.

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If I see 5uA DC I am a happy camper.
If I see below 3.5 with a Carrier I suspect we have a dirty flame sensor, a dirty ground connection or a dirty burner face.




This picture actually has 3 ground screws. If I see a white powdery build up, I remove the 2 mounting screws and wire brush the contact point between the box and furnace...



The face of the inshot burners can rust and the face of the heat exchanger can get a white powdery buildup that I clean to shoot for 5 micro amps DC.



As Grady has posted it is best to have a meter that measures capacitance to check a cap...




Capacitors can hold a charge for ~ 90 seconds after removing power so I wait longer than that then test with a screwdriver to ground the terminals before touching them.
 

Last edited by Houston204; 02-11-15 at 06:04 PM.
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Old 02-11-15, 06:15 PM
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Houston, I noticed in the picture of cleaning the flame rod it was being cleaned with emory plumber's grit cloth. I was taught NEVER to use anything gritty. Use only a Scotch Brite pad or fine steel wool. Does Carrier say it's ok to use grit?
 
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Old 02-11-15, 06:23 PM
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Check out code 34...


I use emery cloth. Fine steel wool is probably better if the flame sensor is already clean and you don't have many furnaces to clean in a day.

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New Carrier furnaces now say to use fine steel wool.
 
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Old 02-11-15, 06:27 PM
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Thanks guys.

My meter doesn't read microfarads, so I'm out of luck there for the time being- I'll try to borrow one that does. If the capacitor is bad, how will that affect the operation of the fan motor?

I'll clean out the nipple, and test the flame sensor, as described, and report back.
I might have some trouble with the temp. rise as I don't think the furnace is running long enough to reach its max temp.

I have cleaned the flame sensor.

I'm very curious to see what condition the squirrel cage is in after I remove the vent pipe- thanks for keeping me from removing the whole assembly Houston.

Sorry I haven't had a chance to complete all these tests yet- winter and trying to keep the house warm have kept me a little preoccupied.

Great pics Houston.

Thanks for your input Grady, it all helps.
 
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Old 02-11-15, 06:32 PM
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There is a formula to calculate capacitance if you have a clamp on amp meter and a volt meter but it would be tough to use it with a blower motor.

The amperage of the start leg divided by the voltage measured across the capacitor terminals times 2652.

amps/volts*2652
 
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Old 02-11-15, 06:41 PM
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I don't have the clamp style meter either Houston. Strike 2.
Either way, if I were able to do the test, should the capacitor be discharged first, or is that defeating the purpose?

Actually Houston, I just noticed your picture about discharging and testing the capacitor. Question answered.
 
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Old 02-11-15, 07:00 PM
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I have a Fluke 902, a Klein CL2300 and a bunch of Fieldpiece clamp meters but I love using this little true RMS meter. I keep it in my shirt pocket at work. It measure 20 million ohms, 2000 microfarad, volts AC and DC and amperage AC and DC. I wish it measured micro amps dc.

Discharge the cap when using a capacitance testing meter.

The cap must be powered with the motor running for the formula method to work.
 
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Old 02-12-15, 10:14 AM
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Hello,

I couldn't get a reading for the flame sensor, set at the lowest range 200uA, the display wouldn't budge from zero.

I reamed out the furnace nipple for the pressure switch hose- with a tiny straight brush used for cleaning electric razors, it fit inside the opening perfectly, with enough friction to clear out anything that might have been in there.

I pulled off the vent pipe, all the way back to the first elbow at the roof stack, to clean out that whitish, rust powder that lay along the bottom of the horizontal pipe, but especially so I could get a look with a mirror up the stack, which was completely clear.

The squirrel cage on the inducer was very clean, no rust, would spin easily if I blew on it, no bearing noise, no looseness when I wiggled it. It looked brand new in fact, which I know it isn't.

One thing I thought might be significant- it's moderately windy here today and I could feel a substantial draft on my face coming down the stack from the roof- this has blown out the standing pilot on the water heater in the past, the vent from which hooks into the same roof stack as the furnace.

I'm just putting the pipe back together, at which point I will fire up the furnace and take some readings to figure out the temperature rise.
 
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Old 02-12-15, 10:55 AM
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That wind could be overcoming the power of the venter. If the same thing happens on a calm day, obviously it would shoot that theory in the foot.
 
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Old 02-12-15, 11:23 AM
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I just took the readings for the temperature rise-

supply air: 104 F

return : 62.9 F = 41.1 F

The furnace plate reads: 40 - 70 F

The burners would only stay lit for about 6 minutes, so I'm guessing the rise could have been more, but it's just within the acceptable range.
 
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Old 02-12-15, 11:40 AM
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Grady,

I found out a while back that the stack where it comes through the roof is not high enough as per standard installation practices, to overcome the effects of downdrafting, the top of the stack actually below the peak line. So the pilot light goes out occasionally, but there doesn't seem to be a difference where the furnace is concerned between a calm or windy day.

At this point I would happily accept that as a solution- I can't rule it out as contributory at times, but I don't think it's the culprit here.
 
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Old 02-12-15, 12:21 PM
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This is from the furnace installation instructions:

'This furnace is designed for a minimum continuous return-air of 60 F db or an intermittent operation down to 55 F db such as when used with a thermostat night setback. Return-air temperature must not exceed a maximum of 85 F db.'

I'm not quite sure how to interpret that 'intermittent operation' part or if it's even significant to this matter.
 
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Old 02-12-15, 01:41 PM
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One other thing I have done that I didn't mention earlier was to have the tester hooked up to the high-limit switch when the furnace was working a little better.
I've done this on a couple of occasions and the limit has never tripped with the burner shutdown.

The service tech was here last week, and I'm pretty sure he checked the flame sensor and blower capacitor, but I've got a call in to him to verify that- he's frustratingly hard to get a hold of.
 
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Old 02-12-15, 02:29 PM
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The majority of the causes of a 31 code are draft related. None point to a flame sense issue. Someone needs to install a digital manometer, pull up a chair, & sit there to monitor the manometer. If the flame fails & the manometer never indicates a pressure at which the pressure switch(es) would open, either a switch is bad (unlikely but not unheard of) or there is an electronic problem.
 
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Old 02-12-15, 04:32 PM
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Thanks Grady,

That sounds very straightforward. Either I'll get one or insist that the tech hook one up next time around.

If the switch did open when it's rated to open, would you then look at the performance of the inducer in this particular case?

The water column value isn't shown on the pressure switch. If it did open, I'm guessing it would be necessary to know if the switch is opening at its rated value, to help rule out the switch and look elsewhere. Is this information accessible?
 
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Old 02-12-15, 04:44 PM
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You might Google the part number on your pressure switch.

Your furnace is a twin to the 58PAV that I grew up servicing and I believe that model opens at .3" W.C. This would probably vary with size.

Have you connected a meter to the pressure switch terminals to see the change in voltage when the furnace drops out?

24 volts across a switch indicates potential, so the switch is open.
0 volts across the terminals (with 24 volts supplied to either terminal) indicates a closed circuit so the furnace should fire up.

I have had to extend vent pipes higher than the ridge of a roof to stop the spill switch from tripping in the past.

I usually only replace pressure switches after they get water in them from a backed up drain or ice.

Do you have carbon monoxide detectors in your home?
 
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Old 02-12-15, 04:46 PM
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Shucks. I was looking at pictures Houston posted thinking they were yours. Somewhere we have to be able to find the pressure switch spec. If you have posted the full model number, I can't seem to find it. If you can do that, I'll call my local Carrier distributor & see if they can tell me. Can't hurt to have a serial number as well.
 
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Old 02-12-15, 06:50 PM
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I put the leads across the pressure switch:

The furnace actually got up to heat and shut down normally- it actually seems capable of doing it if it can satisfy the thermostat within about 8 minutes ( I only put it up about 1.5 F above ambient).

Anyway, I raised the thermostat again, there was ignition, tester remaining at
0 volts, flame lasted less than 30 seconds, and went out before the tester jumped to 26.6 volts with the inducer stopping at the same time as the voltage jump, blower continued, tester settled back to 0 V when the inducer restarted.

This repeated as per my original post, although I didn't let the furnace run as many cycles, with the flame dropping out before the tester peaked at 26.6V with the inducer stopping.

Is the order- flame out first, then pressure switch opening, significant?

We have two detectors, one on the main floor, the other in the basement.
 
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Old 02-12-15, 06:58 PM
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I found the specs for the pressure switch:

Pressure Switch, HK06WC090
make point=.33 in. w.c.
break point=.13 in. w.c.

Good recall Houston.
 
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Old 02-12-15, 07:15 PM
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Yes it is signiificant. I seems the flame loss is not the result of loss of draft.
I'd love to see a wiring diagram &/or schematic to determine current path. Then we could check the safety devices in order.
 
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Old 02-12-15, 07:45 PM
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I've got the schematic here Grady, I'm just trying to upload it.
 

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Old 02-12-15, 08:15 PM
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dms.hvacpartners.com/docs/1009/Public/01/58WAV-1SI.pdf

The schematic is on pg.9- right click and rotate clockwise to view it properly.

I hope this helps.

My thanks to you and Houston for your patient help with this problem.
 
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Old 02-12-15, 08:36 PM
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That edge pin connector is a very likely culprit.

I would unplug it and look for corrosion.

Looks like the circuit is orange and yellow.

What year is your furnace? 1992 like the manual that you posted?
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Old 02-12-15, 08:45 PM
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The first 2 digits in the serial number indicate week and the 3rd and 4th digits in the serial number indicate year.
 
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Old 02-12-15, 08:56 PM
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I'll take a look now. It looks like connections 2 and 4 are yellow and orange respectively.

The furnace was manufactured in 1993.
 
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Old 02-12-15, 09:48 PM
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For the moment, I can't budge that connector Houston. It seems to fit much more tightly than it did on the old board.

I'll take another crack at it and get back to you.

Could all of this come down to a bad connection?
 
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Old 02-12-15, 10:25 PM
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It very well could be the edge pin connector.

Klein Tools Test Lead Set-69410 - The Home Depot

If you clamp your meter leads across the pressure switch and see it drop out on a pressure switch fault, but you do not see 24 volts across the pressure switch, it would point away from a real pressure switch problem.
 
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Old 02-13-15, 05:33 AM
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The volt meter is wired parallel with the pressure switch, not in series as with the flame sensor testing.
 
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Old 02-13-15, 06:19 AM
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Hello Houston,

In post 26, I describe putting the leads across the pressure switch and the resulting reading of 26.6V, but after the flame had dropped out. Would this rule out the switch as the culprit?

I took a look at the the tabs that accept the connector on the old board, and saw no signs of corrosion there, but I'll try to get that connector off and see what shape it's in.
 
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Old 02-13-15, 07:17 AM
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Just a couple of thoughts:

Although the performance of the furnace has been poor, it has been consistent in terms of the shutdown process I have described-

: would an electrical problem manifest itself with this regularity?

: that initial 6-8 minutes of heat can only be achieved if I let the furnace "rest" for a number of hours between attempts.

Any thoughts?
 
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Old 02-13-15, 08:02 AM
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Can you guide me in how to check inducer voltage? ( one of the checks from the service list for a code 31)

This is a check I haven't performed yet.

Thanks
 
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Old 02-13-15, 11:16 AM
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It sounds like you have proven that the pressure switch is dropping out if you get 26 volts across the pressure switch when it drops out.

Does the inducer continue to run when dropout occurs?
 
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