Goodman- GMP 075-3 won't start.

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Old 12-28-14, 07:04 PM
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Goodman- GMP 075-3 won't start.

In heating mode red light is on but nothing happens. In cooling mode fan starts up and it seems like all is working. I won't know till it is hot again outside. What could be a problem in a heat mode?
 
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Old 12-28-14, 07:17 PM
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Welcome to the forums.

On a call for heat the draft inducer blower fan should start. Do you hear any click from the furnace when t'stat is set to a call for heat ?
 
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Old 12-28-14, 08:47 PM
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Not a sign of any clicks. I bypassed tmostat but it didn't help
 
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Old 12-28-14, 09:56 PM
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Did you have the blower door back on ? Otherwise you need to hold the safety switch in place.

Go to the terminal board in the blower compartment. Make sure power is off anytime you are changing thermostat wiring. Connect a jumper between W and R. Power furnace back up while holding the safety switch in. Does the furnace start ?

The following is your manual..... Goodman GMPH manual.PDF
 
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Old 12-28-14, 10:08 PM
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Tried it all to no effect. According to docs constant red light on control board is positive sign of functioning unit. I tested contacts on transformer and it blew out my tester. Red light stayed on.
 
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Old 12-28-14, 10:19 PM
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I tested contacts on transformer and it blew out my tester.
That doesn't tell me anything about the problem.

If the red light is on then your 24vac transformer is ok.

Did you try the R to W jumper ?
 

Last edited by PJmax; 12-28-14 at 10:38 PM.
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Old 12-28-14, 10:40 PM
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I've checked on red light status indicator on a control board from manual on GMP model- it clearly states that system is ok when red is on, not flushing.
I will get new tester tmrw and will run it on every contact for currency. Thank you for now.
 
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Old 12-28-14, 10:51 PM
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Yes I tried jumper on R and W
 
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Old 12-28-14, 11:51 PM
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The red light on solid means the board is powered. It doesn't mean the board can't be bad it just hasn't logged any faults yet.

You said the blower works in the A/C mode. That would be the same as connecting R to G on that control board. See if connecting R to G still activates the blower.

Check for 24vac from R to chassis ground.
 
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Old 12-29-14, 06:32 AM
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Blower worked ok with R connected to G.
R to ground blew the fuse on a control board.
 
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Old 12-29-14, 08:52 AM
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Yes....connecting R to ground will blow the fuse.

If you get no changes or sound when you connect R to W then it looks like your control board is defective.
 
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Old 12-29-14, 11:40 AM
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Checked all the contacts on control board for continuity and all five power lines to main blower are showing no signal along with a black one going to igniter.
connected again R to W only to see red light on a CB and barely distinct humming sound. R to G still makes blower run.
 
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Old 12-29-14, 07:39 PM
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When you connect R to W..... you should hear the distinct sound of a relay or two closing. One relay is for the inducer fan.

You most likely hear a relay close when you connect R to G.
 
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Old 12-29-14, 08:25 PM
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what would you advise me to do next- getting a new control board?
 
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Old 12-30-14, 07:03 PM
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Fixed it!!!

Thank you for troubleshooting the issue it works now with a new circuit board just fine.
Let's see how cycle would run out but so far it ok.
 
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Old 01-01-15, 05:51 PM
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Today second gmp050-3 failed to keep flame on

here is the cequence repeating itself.
Click- fan starts
-"- Ignighter lights to red
-"- Burners fire up
-"- Main blower starts
5 sec.
-"- Burners shuts down, ignighter cools down
10sec
-"- Ignighter turns red
-"- Burners fires up
-"- Shut down cequence repeats itself
Meantime all fans are working
 
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Old 01-01-15, 06:11 PM
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Is there enough air flow? It sounds like there is a safety stopping the process. If you take off the access door & hold the switch, will it run longer?
 
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Old 01-01-15, 06:17 PM
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All that testing was done with an open covers by pushing safety start up button upfront. Tried to reset all 4 sensors and
Now a new failure: gas burners Relay clicks but gas doesn't flow or burns up. No smell of gas. Fan works. Blower doesn't .
Correction on model :-- GMP 075-3
 

Last edited by mikedzh; 01-01-15 at 06:57 PM. Reason: Correction
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Old 01-02-15, 06:49 AM
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What about jumping the thermostat, in case that's bad? I don't know what other safeties are on that system but that's where I would look. Everything else seems to be functioning properly. Other than safeties, the next stop would be the control board.

Another thought: Is there a humidifier on that system? You might want to disconnect that temporarily.
 
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Old 01-02-15, 09:36 AM
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Safety shut off sensors

After checking for continuity on all four sensors and manually resetting them by pushing plastic buttons I finnally got it running. It did looked like one of the sensors got stuck( top one) in open ( cut off) position.
I might be mistaken but it was the only thing I was messing up with.
 
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Old 01-02-15, 02:47 PM
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It sounds like you found the answer.
 
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Old 01-02-15, 03:10 PM
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Only the one or two sensors directly over the burner should be resettable.
They are the flame rollout switches and can have a red button on them.

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Old 01-02-15, 05:34 PM
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Cluster of wires was actually sitting on top of the top sensor and I had it fixed too. Thank you guys. I am getting really good feeling that this furnaces will run for another 5 years. I've got 19 years out of them.
 
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