Godman Package unit not heating


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Old 10-02-13, 02:26 PM
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Godman Package unit not heating

Goodman PG024074-1AB 1989 Package unit ground mounted.
AC working good but no Heat.

From 2003 to 2009, I installed heat exchanger, Honeywell gas valve, rollout switch, transformer 240/24 V AC, contactor, and new thermostat.

All worked well until last spring when furnace quit. Used Air Conditioner all summer. Now need heat but unit doesn't run.

I have diagrams, parts list and tools.

Thermostat 4 wires. Tests prove heat, cool, fan, all working from thermostat.

Vent fan motor runs fine, Have continuity through rollout switch and limit switch.
In the Burner area, no clicks or any activity.

Blower fan runs for AC but does not run for Heat. Removing rollout switch from circuit does not force blower fan to run (as it used to do).

Does that sound like a bad Ignition Control Module B13707-24
Or a bad Fan Limit Control B13701-21
Or something else?

I apologize for being sparse on voltage measurements. At age 81 health limits me from testing more than a little per day.
 
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Old 10-02-13, 10:04 PM
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Does this unit have a pressure switch?

Can you feel air discharging from the exhaust vent outlet near the burner section?

If you feel air and have a pressure switch, remove the rubber hose between the pressure switch and unit and clean the metal barbs that the hose connects to with a paper clip. Inspect the rubber tubing for holes when you remove it.
 
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Old 10-03-13, 08:48 AM
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No pressure switch that I can find and not listed on parts list or on diagrams and no rubber hose.

On a call for heat, the vent fan runs but nothing else. No other noise or activity of any kind. I can leave it on "Heat" for hours and nothing else happens.

Call for Cooling and after a short delay, air conditioner works until thermostat reaches set temperature.
 
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Old 10-03-13, 10:01 AM
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When you set the thermostat to heat can you hear a click at the furnace control board? Do you hear a "sparking" like it is trying to light? Are these the parts you have in your unit?
 
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Old 10-03-13, 01:04 PM
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Thank you.

T'stat set for heat. Wife turned on while I sat at furnace. No clicking on board, Vent motor running. Waited 4 minutes and turned off power.

Pictures; (some appear a little different than my old original parts).

1. Is similar to my ignition and sensor. Both wires go to Ignition control module.
2. Linit switch. Mine is mounted on single 3 inch platform. VOM shows continuity.
3. Rollout Sensor. Mine is resettable and VOM shows continuity.
5. Replacement for original B13707-24 ignition control. My original has notice, "Intermittent pilot 100% shut off." Another notice says, "90 second lockout, 5 minute retry."

Thank you for your time and effort.
 

Last edited by Doug D; 10-03-13 at 01:31 PM.
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Old 10-03-13, 01:38 PM
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You will need to use your meter to see if you have 24VAC going into the control board and coming out of the board. Using your schematic locate the two wires that provide 24VAC to your control board. Set your meter to VAC and place a lead on each of the two terminals. You should have around 24VAC. Then use your schematic to determine which terminals send out 24VAC and test to see if you have 24VAC going out when the furnace is trying to start. You said you had a replacement control module. Can you post the model number of that module?
 

Last edited by firedawgsatx; 10-03-13 at 02:34 PM.
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Old 10-03-13, 04:50 PM
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I'm sorry but I wasn't clear. I don't have the new control module but I searched for a replacement in case I need one. My control module is the original B13707-24.

I'm going to do another voltage test in the morning. I have 26.9 VAC coming from the transformer to the board but only 13.79 coming from the board to the control module.
Tests were done with wires connected and call for heat at thermostat.

When thermostat was turned on, I heard a click from furnace circuit board.

Lighting was not good and mosquitoes were bad. I don't doubt the readings which I did over and over but I'm going to test again in the morning..

Previous open line tests at the thermostat show 23.5 for heat and 26.4 for cooling. Both fall to "0" on a call for heat or cool which I think shows me a good circuit to and from the thermostat.
Thank you.
 

Last edited by Doug D; 10-03-13 at 05:34 PM.
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Old 10-03-13, 05:54 PM
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You need to have around 24VAC coming out of the control board. Which terminals were you measuring on the "output" side of the board? Does your control board look exactly like the one in the photo I posted earlier? If so, you should get 24VAC between the MV/PV and PV terminals when you are trying to ignite the pilot light. If you don't get 24VAC then your control board is probably bad. Have you checked all of the wiring connections?
 
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Old 10-04-13, 09:59 AM
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The transformer is sending a steady 26.7 VAC.

I wasn't sure where I should connect my meter leads to check the the old type Ignition Control Module but I tested voltage from transformer + (positive) to each (connected) Ignition Module wire.

24 VAC -TH = 24.7 and gradually dropped to 18.
MV = 14.9
PV = 26.4
Sensor = 19.0
Ground/Common = 16.4

The circuit diagram is posted on my Web Site if you want to look. 01

Thank you.
 
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Old 10-04-13, 10:11 AM
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The voltage from the transformer should not gradually drop from 24V to 18V. With the thermostat set to heat place one probe on the PV terminal and one to chassis ground (a screw on the cabinet) and see what you read.
 
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Old 10-04-13, 12:13 PM
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Thermostat set to heat.

PV to chasis ground "0"
MV to chasis ground "13.3 V AC

Retested numerous times. Same result.
 
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Old 10-04-13, 12:17 PM
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Test between PV and TH when set to heat.
 
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Old 10-04-13, 12:50 PM
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T'stat set to heat 82, room is at 74.

PV to TH = "0.2 V AC"
MV to TH = "7.9 V AC" (this one to prover Volt meter is working).

During these volt tests, Vent Motor is running normally.
 
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Old 10-04-13, 12:58 PM
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When the thermostat is calling for heat you should have 24V from PV to TH or PV to Common (I believe that is where the blue wire is connected). For the ignition module to to create a spark you have to have 24VAC into the module and 24VAC out of the module. Have you checked all of the wiring connections to make sure they are not loose or corroded. A lot of times problems turn out to be bad wiring connections. What voltage do you show coming out of the vent motor when it is running?
 
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Old 10-05-13, 06:50 AM
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Following your testing directions, I think the problem is the Ignition Control Module. I found an exact replacement for the old one at a reasonable cost. I ordered it last evening.

Thank you for the help.
 
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Old 10-05-13, 07:07 AM
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If you checked all of your connections for tightness and corrosion and checked all of your grounds (especially at the module) and based upon your voltage readings it does point to the module. The MV/PV shown in your schematic is the common for your module. Please let us know the outcome.
 

Last edited by firedawgsatx; 10-05-13 at 07:45 AM.
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Old 10-14-13, 05:40 PM
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I found that my brand new combustion Vent motor had a bad centrifugal switch. It would sometimes work for a few seconds then no more. Finally the switch quit completely while the fan motor continued running just fine.

I bypassed the 24 V AC line from the switch in-out and the furnace runs like it should. I just bought that new vent motor a little over a month ago. New doesn't always equal better.

Thanks for all your suggestions and help. I really appreciate it..
 
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Old 10-14-13, 07:01 PM
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Glad to hear you determined what the problem was and thanks for letting us know.
 
 

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