Blower runs for 30 seconds then quits
I bought this house last year. It was a repo. There is no info to be had on its history before me.
A/C has been working fine this summer until yesterday. I’ll include a few possibly helpful symptoms from the winter heating months also.
Forced air, split system
Snyder General built in 1989
Model GUD100A020ATM
Outside -
compressor and fan both run when called by the thermostat. Nothing looks out of the ordinary. Fins are pretty clean and there’s no debris in or around the unit.
I did notice a small amount of icing on the line. I don’t know if that line was “in” or “out”. (this is where the little bit that I do know, ends)
Inside -
The filter was dirty. Actually, it was really grungy. Okay, the truth is, it was caked with muck. No, I’ve never changed it before. Lesson learned… it wont ever get like that again.
Fins on the fan inside the blower housing are a little dusty on the surface, but there’s nothing caked on, just a fine layer of ordinary looking dust. It spins freely in either direction by hand.
The back side of the motor is caked with grunge. It’s thick and paste-like.
There is no visibly apparent bulging on the capacitor
All connections are snug and nothing changed or was touched from when it was working 3 days ago, to yesterday when I turned the system on after being gone for the weekend.
When I adjust the thermostat to trigger cooling, the compressor and outside fan start right up and continue to run until I tell it to stop by adjusting the t-stat. The inside fan will come on after about a minute, run for 30 seconds then shut off. It will come on occasionally and repeat the shutoff. With cooling off or on, I can turn the fan switch to “ON” from the t-stat, and the same thing happens (starts after a minute, then shuts off after 30 seconds).
In winter both in this year and last year, I had fan problems with it not coming on at all when set to Auto. If I turned the t-stat fan switch to ON it would come on and stay on till I turned it off.
It’s getting power, because it does come on, it just doesn’t stay on.
Following the wires around, there’s a fan limit switch (set at on/off: 80/125 and off: 190, a capacitor that isn’t bulging but is 20 years old, and a little chunky black plastic thing (a relay?).
I really can’t afford a service call right now.
Any help with diagnosing the problem would be appreciated.
Also, what would be the appropriate way to clean the gunk off the back of the motor? Carb cleaner works great on most sources of gunk on my dirt bikes… but I’m thinking it’s not the best choice in this situation.
Thanks in advance for your words of wisdom….
If you have a volt meter & know how to use it, make sure the motor is getting power when it shuts down on its own. If it is not getting power you will have to trace the circuit backward to find out why. If it is getting power, the capacitor could be weak & causing the shut down. From what you have said about things being dirty, my guess is the motor is getting hot internally & shutting itself off. You are likely going to have to replace the motor. When you do so, replace the capacitor as well.
