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Fraser-Johnston furnace blower motor
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Posted by jgarrity (My Page) on Sat, Jul 15, 06 at 12:31
| I have a fraser-johnston horizontal furnace installed for 14 years. Just 2 days ago, the blower motor stopped working. The a/c was on but there was no air flow through the vents in the house. Inspection showed that the A-coil was all frozen up. If I set the thermostat to supply heat, the unit turns on, the safety switches allow the pilot to light. But the blower never kicks on...so the unit just resets itself. I performed the troubleshooting tests from the manual and they told me that I need to replace my 24v transformer. I did that and the problem still exists. If I connect the AC side of the transformer to 110VAC, should I be able to read 24VDC from the output side (without anything hooked up to it). If so, then maybe I purchased a defective transformer! Can anyone help ?! |
Follow-Up Postings:
RE: Fraser-Johnston furnace blower motor
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| I've never worked on a Fraser Johnson furnace but I can't imagine anything 14 years old using DC control voltage. Don't you mean '24 VAC'? The fact that your air conditioning was working and you got the heat to work should be telling you that there is nothing wrong with your transformer. Its all the same low voltage circuit. Your problem is more then likely in the fan circuit, either line or low voltage. |
RE: Fraser-Johnston furnace blower motor
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Yep, if you have your DVM switched to DC on a AC circuit you aren't going to see much!
Open-circuit secondary voltage of a unloaded 24 VAC control transformer is usually in the upper 20's. Comes down with loads.
I would be checking the voltage across the coil terminals of the blower relay. With T-stat calling for cooling, and the blower door safety interlock switch closed, should see ~24 VAC across the relay's coil terminals. The relay's Normally-Open fan contacts should close, powering the blower motor. Of course, all personal safety warnings apply for electrical shock, and fingers in the blower wheel! |
RE: Fraser-Johnston furnace blower motor
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Hi all, new here. Does anyone know why I am getting only low speed on my fan. Its a fraser johnston model g9t1202oupd13a.
I tryed to turn on the ac and it ran for awhile and stoped blowing. Is there some place to get the schematic for the fan speed control. Thanks Roger |
RE: Fraser-Johnston furnace blower motor
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| Does your unit have a pcb in the furnace? If so look for a blown fuse. FJ is owned by BES which also owns York. IMO it is a very good product that will give many years of service. If no PCB, it is a common wired unit without many surprises. The PCB makes diagnostics more difficult. Most blower motors have 3-5 speeds. They can be tested with direct voltage. If they do not run at all, replace the capacitor, otherwise replace the motor. If the unit froze up, you either have a dirty coil, a bad fan motor, or are low on freon. AC should be on anything other than low speed. Heat is usually on low speed. |
RE: Fraser-Johnston furnace blower motor
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Hi Bob thanks for the response. It does have a pcb.I have the schematic from the back of the door of the furnace. Is there a way I could change the jumpers to see if I can get a higher speed on the fan. One last ? what does the "imput" colum refer
to on the carts upper right corner mean.
[IMG]http://i159.photobucket.com/albums/t136/rogerw_photos/Picture196.jpg[/IMG]
Thanks again Roger |
RE: Fraser-Johnston furnace blower motor
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| Heater btu's. Lowest speed is red. Medium speed is blue. High speed is black. Turn off the power before continuing. Move the blue to where the black is currently in place. See if the motor changes speed. Remember, most units have a delay with the fan starting. Depress the door interlock also. Put the fan switch to on, at the thermostat. Keep your hands away from bare wires and moving things. Be very careful not to disturb the small wires from the stat. They break easily. If the motor does not start, the cap could be bad. It is cheap to replace. |
RE: Fraser-Johnston furnace blower motor
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Hey Bob if your still out there, I have a update. I moved the blue wire to the cool terminal on the pc board. The speed did not change (seemed to run at med speed still). I did notice one thing when I had the black wire on the cool terminal on pcb it would run for about 30 seconds and stop. when I put the blue wire on the cool terminal it ran for maybe
a minute before stoping. Another thing I never had the high speed, since the problem started about 5 or 6 days ago. Im thinking either a motor problem or run capacitor. One last ? what is the "park" on the pcb mean. There is cool ,heat, park , park , terminal for the fan to hook up to. Is this the btu you mentioned? used only on the heating setting? Ok 1 more ? is the fan 110 volts ac. Thanks again Roger |
RE: Fraser-Johnston furnace blower motor
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| Na getting close to the answer |
RE: Fraser-Johnston furnace blower motor
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| Park is usually a dead plug where the wire is put to keep it safe from shorting out against anything. You probably need a new motor. The PCB seems to work fine. If the motor does not growl while operating, the motor is probably bad. If it growls, replace the cap first. As to the techs out there- This is the beginning of my new standards for this site. I will help as much as possible to anyone that seems capable. I will try not to insult the poster. A motor replacement is a good test of skills. You need a few tools, and just a little experience with electricity. Like how to switch off the breaker or switch. I am tired of hearing that someone paid $500 for a new $50 motor. Always replace the cap. No excuses, replac3e the cap with a new motor. Do not pass go, until you replace the cap. Otherwise go to jail for your stupidity. |
RE: Fraser-Johnston furnace blower motor
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Thanks Bob I will check into getting a motor and cap tomorrow.
I feel comfortable changing it out. I built a resistance soldering station for 5 dollars using a 12 volt car battery charger I had around. I use it for soldering model train tracks and it works fine so im not new to electrical projects.
Thanks you very much Bob. Roger |
RE: Fraser-Johnston furnace blower motor
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| Hi Bob just wanted to let you know my ac is kicking again. Replaced the motor and cap and have hi speed again. Thanks again Roger |
RE: Fraser-Johnston furnace blower motor
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| I replaced the hot-surface igniter and I can't get to light. How do I know if I'm getting any propane to the furnace. everything else seems to work. |
RE: Fraser-Johnston furnace blower motor
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| I have a Fraser Johnston Furnace that needs service. I live in San Jose, Calif. Can you recomed a service person. |
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