Bryant 310AAV wont light


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Old 10-17-10, 09:03 AM
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Bryant 310AAV wont light

I haven't searched the forum yet, but I thought I'd throw this out there, first, to see if any experts can help me out.

I've got a Bryant 310AAV/310JAV GAS furnace. We just got home from vacation and when I woke up this morning the house was very cool. Granted, I turned the furnace down to 64 before we left (to save a few bucks), but now it wont light off.

I tried the "shut off the gas control switch, gas valve, breaker" deal a couple of times. Here's what I get:

The blower comes on for approx 90 seconds, during which the LED gives me a code of "12" Blower on after power up, which is normal for this operation.

Then the (pardon my ignorance) the little blower (not the main cased one) that is mounted on what appears to be a three-point soft mount, attempts to turn (1/4 turn max) and I get a LED code of "13", or Limit Circuit Lockout. Nothing after that.

That's as far as I've gotten.

Any advise is much appreciated.

Thanks,
- Pete
 
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Old 10-17-10, 09:19 AM
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As you note, the circulating fan running for 90 seconds is normal.

After that, what should happen is that the small inducer fan motor should start and come up to speed to cause air to circulate through the heat exchanger and venting system. A pressure switch turns on the next stage of the furnace when it verifies that the inducer motor and vent system are operating properly.

From your comment, apparently the inducer motor is only being switched on for an instant and then the power is being switched off. You want to verify that by checking to see what is happening to the 120 VAC power that should be switched on and stay on to operate the inducer motor.

The limit switch error code implies that the limit switch is stuck open. You should check to see if there is 24 VAC voltage on both side of the limit switch. If there is, the limit switch is closed and OK, and the problem is likely a defective circuit board that is failing to turn on the inducer motor and giving a false error code on the limit switch.
 
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Old 10-17-10, 09:34 AM
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SeattlePioneer,

Thanks for the input. Everything you said seems logical. I'll get my meter out and check the voltage at the inducer motor to see what's happening. I'll also look for the limit switch. I have the manual for the furnace, but it does a lowsy job of showing me where the actual parts are.

I'll get back to you with what I find.

Thanks again,
- Pete
 
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Old 10-17-10, 09:48 AM
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The limit switch is designed to open if the furnace overheats. If it overheats the limit switch opens and shuts off the burners.

One way they can fail is by not making a continuous circuit when they are cold and should pass the 24 VAC voltage through the switch from on contact to the other.

If you find 24 VAC on one side of the limit switch only, another way of double checking that the limit switch is the problem is to use a jumper wire to temporarily pass voltage around the switch to the second contact on the limit switch. If that starts the rest of the furnace ignition cycle, that confirms that the limit switch is the problem.

If that happens, a third check is to lightly rap on the limit switch with the handle of a screwdriver to see if that causes the limit switch to close.

Good furnace repairmen look for ways to test for a bad part in multiple ways when possible to confirm a diagnosis.
 
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Old 10-17-10, 11:36 AM
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Well, I had a burst of voltage across the inducer fan motor posts (blipped to approz 63VAC) and then same, same - 0VAC and code #13.

Now, I see two "switches" on the furnace. One straight back, below the inducer fan motor, and one near the to the right of the burner area. Are one of these the limit switches or would it be somewhere else.

Again, thanks for all the help.
- Pete
 
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Old 10-17-10, 12:20 PM
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Usually the limit switch will be in the middle of the furnace and above the burners a ways.

Also usually a limit switch is listed as "L" for limit with the temperature it opens.

L160 f or L180 f might be examples.
 
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Old 10-17-10, 01:43 PM
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Well, I found three limit switches on this unit. The one you described was a L180 (limit). I also found one by the burner area (L350 - flame rollout?) and another in the case (L200 - draft safeguard?). I bypassed each one individually and the furnace behaved the same way (a momentary charge on the induced draft motor followed by an error code of #13 Limit Curcit Lockout). I removed and gently cleaned all three limit switches as well but nothing changed.

I looked at the manual and the error code for #13 Limit Curcit Lockout description is as follows:

"LIMIT CIRCUIT LOCKOUT" - Lockout occurs if the limit, draft safeguard, flame rollout, or blocked vent switch (if used) is open longer than 3 mintues. Control will auto-reset after 3 hours. See code 33."

Code 33 is as follows:

"LIMIT CIRCUIT FAULT - Indicates the limit, draft safeguard, flame rollout, or blocked vent switch (if used) is open. Blower will run for 4 minutes or until open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #13. If open less than 3 min status code #33 contineus to flash until blower shuts off. Flame rollowout switch and BVSS requires manual reset. Check for:
- Dirty filter or restricted duct system (I replaced the filter this morning)
- Loose blower wheel (seems fine)
- Defective switch or connections (checked all wires into and out of control panel and all switches/motors/etc)
- Defective blower motor or capacitor (the blower motor runs fine in the first test)
- Inadequate combustion air supply (flame rollout switch open) (I bypassed this one as well to no avail)
- Restricted vent (hmmm?)
- Proper vent sizing (nothing changed here)
- Excessive wind" (nope, not today)

Thought I might try to jump the inducer draft motor directly from the board to rule out the motor as well.

But in the end I'm thinking maybe the control board needs replaced? Any more ideas?

Thanks again. I really do appreciate the help.
- Pete
 

Last edited by pmpilot; 10-17-10 at 02:26 PM.
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Old 10-17-10, 03:22 PM
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Personally I'd use an AC voltmeter to test for 24 VAC along that circuit.

But it sounds like a bad circuit board.

If it were me I'd be checking to be sure all the correct voltage inputs were in place to be sure some other issue isn't causing the problem. Before replacing an expensive part, you want to eliminate as many possible alternative issues that could be causing the problem.
 
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Old 10-17-10, 05:09 PM
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I used the voltmeter but it doesn't give me much information. At all limit switches, the volts are zero until right after blower 90 second cycle quits, at which time you get a surge of voltage and then zero again, just like the induced draft motor contacts indicate.

I did notice that two of the limit switches have resets on them (a plastic tab like button that protrudes out the center of the switch). I tried reseting both of these but heard no audible click or change in the boot.

I think I'm hearing a loud click on the control panel (probably a relay). This could be the problem. Then again, it may just be the blower relay turning the blower off...

Boards range in the $115 to $200 ballpark. Still not convinced that's the problem, but that's my best guess.

- Pete
 

Last edited by pmpilot; 10-17-10 at 07:52 PM.
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Old 10-18-10, 09:15 AM
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Before I get the board, does anyone know how to overcome the lockout procedure? I was assuming that when I throw the breaker and then fire it up that it's not in lockout mode anymore. But maybe all the bypassing I'm dong is for nothing if the control board is remaining in a lockout mode.
 
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Old 10-18-10, 05:54 PM
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Originally Posted by pmpilot
I used the voltmeter but it doesn't give me much information. At all limit switches, the volts are zero until right after blower 90 second cycle quits, at which time you get a surge of voltage and then zero again, just like the induced draft motor contacts indicate.
Explain how you are doing this test, exactly. Where are you putting the probes of the multimeter?
 
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Old 10-18-10, 06:03 PM
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There is no voltage going to the limit switches during the first 90sec blower phase. At the end of that phase a jolt of current is sent to the blower (induced draft motor) reaching approx. 63volts (measured where the hot and neutral wire connect to the motor). It spins a quarter turn then the the thing hangs with a code of 13. Same at the limiters. Small jolt of current (approx 24 volts) for a split second, then nada.

I jumped the blower (induced draft motor) directly to the control panel and it powers up fine.

I've jumped all four switches with alligator clipped wire and nada.

I did notice a little corrosion on the board last time I looked. We did have a basement flood (inch or two) a couple years back. The board could have collected that moisture and now its telling me.
 
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Old 10-18-10, 06:17 PM
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Originally Posted by pmpilot
There is no voltage going to the limit switches during the first 90sec blower phase.
If by blower, you mean the draft inducer - there should be. If there isn't, there is a problem. Confirm that is the blower you are referring to.

Now just so you know, if you use your multimeter to test switches across the terminals, you will show 0 volts if it is working! I prefer to spare people that confusion and test between each spade of a switch, to ground. With THAT kind of test, you should show 24 volts for BOTH tests.
 
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Old 10-18-10, 06:20 PM
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The draft inducer is not receiving any power until after the blower (the big cased one) stops blowing for 90 seconds. At that point it gets a split second of power, enought to turn it once quarter turn maybe, and then code 13. The blower (big one) blows fine. And I jumped the draft inducer straight from the board and it runs fine. I'm not sure how the sequence goes though...
 
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Old 10-18-10, 06:35 PM
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Sequence is: breaker, furnace switch, blower door switch, transformer, thermostat, when call for heat -------->: relay to turn 24 volt thermostat signal to 120 volts for inducer, inducer runs, safety circuit completely energizes as all safety switches are closed such as limit switch(es), roll out switch(es), spill switch on inducer fan, and pressure switch(es) - to complete 24 volt signal to ignition board telling board everything is okay, so then ignition occurs. The inducer is running the whole time there is a call for heat. The inducer should start up about 15-45 seconds after thermostat gets a call for heat. A relay(as I mentioned) to the inducer sequence is the only time delay impedement. Inducer runs during entire call for heat, ignitor comes on, burners start, blower fan comes on by heat or by timer(which may come on almost right away if by timer, but likely is delayed some) - continues to run some after call for heat shuts off and after flame-out to recover heat in furnace. End of cycle.
 
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Old 10-18-10, 08:14 PM
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Is the motor overheating? Any chance the blower wheel is fouled? Check the blades on the squirrel cage wheel for buildup. It does not take much build up to render the blower wheel ineffective, which also means the motor spins faster than it should without resistance.
 
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Old 10-30-10, 11:07 AM
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I appreciate everyone's input. It was very valuable as troubleshooting is the biggest challenge.

Anyway, I've posted on how I bypassed all the limiters with no luck. Noticed that the induced draft fan gets a split second of voltage, then quits. So I jumped the fan directly from the control board and if fired up and ran with no hesitation. Left me thinking that the control board was faulty.

Found one on eBay for $24! Used, though. Anyway, it came, I slapped it in, and viola, we're back in business.

Found a little corrosion on the old board, likely moisture from a hot water heater leak we had last year.

Again, thanks for the info. Learned a lot. Saved a lot!
- Pete
 
 

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