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I have a York 5ton heater/air conditioner and the cooling fan inside the unit will not shut off and the blower motor only works sporadically. Thoughts?
Optional Information: Make: York Model: D1nh060n09006c Already Tried: Just observed the internal cooling fan running without the thermostat being on
In order to find the fault you will need to do the necessary work. I don't guess- I will only do a step-by-step diagnosis, so it would be imperative that I receive definite answers from you on whatever I ask. If you cannot give me what I need to know then this will go unsolved. A voltmeter may be needed here. So, post back if and when you can do this. You must be where the unit is to do this as well-I will not give a bunch of "if this-then that" type scenarios.
I can get to the unit with a volt meter in about two minutes. Ok?
That is fine. First off there is no 'cooling fan'. The fan by the burners is the draft motor and it should only run on the call for heat. Disconnect the white thermostat wire from the control board that came from your t/stat and see if the blower still runs. This will eliminate any t/stat issue.
White wire disconnected and motor still running
White wire disconnected and motor still running. Still with me?
Yes. You may have an open safety limit here. Check them - all should measure closed and all are in series with one another. I am getting ready to eat dinner and will return when I am done to finish this with you.
Not sure how to check them or where they are. Getting dark here. Should we continue this tomorrow?
That would be fine if it's dark by you. I will post to you in the am. All you need to do is see if they have continuity or not- you can test with a meter or touch the 2 wires on them together. One is by the burners- just follow the wires and you will find the rest of them. Turn the power off then on to reset the furnace if you elect to touch the wires together.
By continuity you mean check ohms across the two wires?
Yes, but you must remove at least 1 wire otherwise you do not know what the reading is from. Test the device, not the wires.
I found three. The one by the gas tubes and the one in the squirrel cage show to be closed. Upon checking the third, the blower motor shut off. Does this mean anything to you?
The one where the blower turned off had to be open; it may have reset just from you touching it as these can stick open at times. If your blower is sporadic then that would obviously be suspect as the limits open when the furnace overheats. So, the next thing is to check the blower motor- it should be running whenever it has power to it. I am referring to the blower motor with the squirrel cage- not the draft motor. The blower is powered from a terminal on the board marked heat and you can easily find this by following the motor leads as one speed is used for cool and another for heat.MRANSWER40930.0658012732
Ok. Came back down, heat seemed to work ok. Turned on the ac and the blower seemed to work for about three minutes and it then slowly started to decrease in speed until it stopped completely. Compressor was still running but no blower.
Ok. Came back down, heat seemed to work ok. Turned on the ac and the blower seemed to work for about three minutes and it then slowly started to decrease in speed until it stopped completely. Compressor was still running but no blower. Just ran heater again and after about four minutes, the blower stopped again as well.
The motor is bad OR the capacitor for it is. If the capacitor looks swollen or has evidence of oily residue then it is bad. You can simply buy a new capacitor if in doubt and see if it works as you cannot test them. IF the motor winds up being bad then be sure to use a new capacitor for it -the correct capacitor size needed will be right on the box or the motor. Not doing that is like using a used oil filter on an new engine. Any local hvac supply will have the parts as they are generic in nature and easily matched up- getting the exact factory part is typically not necessary and avoids extra expense as well.
You did a good job here finding the problem, so follow up on what I said and replace whatever is faulty at this point.
Acceptance is what I am after here, so if this helped you get to the bottom of the failure then it is appreciated.
After running the unit, it appears the safety limit switch is open again. Is it possible that is the problem and is there a way to definitively diagnose that from the motor going bad?
The limit will open from no air flow as how can the heat be removed with no air flow thru it? I mentioned that issue earlier. The blower motor is supposed to run when the limit opens as well and the limit has absolutely nothing to do with the operation of the blower motor in a/c. If the radiator fan on you car is not working and the engine then dies how can you think that the engine is causing the issue?
Don't over-think this. You have my diagnosis and I am sure of it as well. There is nothing odd about a fan motor failure.
After running the unit, it appears the safety limit switch is open again. Is it possible that is the problem and is there a way to definitively diagnose that from the motor going It is not the limit switch in the squirrel cage or by the burners, but the one that screws into a non visible area. Do you think it is still the fan motor if this is the area getting hot?
I already replied to this at 9:22 my time- did you not see it??? Check your junk box.
Home Appliance Technician
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