Air Conditioning - a/c not turning on, suspect capacitor
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di_rosa
06-27-09, 04:26 PM
hey all,
it was that time of year again, but when i flipped the switch, nothing!
my furnace fan is turning on, but just blowing warm air.
here is what i've checked/verified:
-both breakers "on" (inside and out)
-confirmed power at the contactor
-confirmed contactor triggers when thermostat inside set to "cool"
-cleaned the contacts on the contactor
-contactor is happily humming
-confirmed fan not seized (spins smoothly)
there is no reset button i can see under the panel cover. if it matters, it's an Aire-Flo unit.
i was under the impression the low pressure switch would kill the compressor, but the fan would still turn on?
the only reason i suspect the capacitor is that all that's left (as far as i know) is the capacitor, compressor, refridgerant, and out of those, the capacitor is the cheapest and easiest to change :D . though, the capacitor isn't swollen, it's just rusted to crap.
so, any thoughts?
it was that time of year again, but when i flipped the switch, nothing!
my furnace fan is turning on, but just blowing warm air.
here is what i've checked/verified:
-both breakers "on" (inside and out)
-confirmed power at the contactor
-confirmed contactor triggers when thermostat inside set to "cool"
-cleaned the contacts on the contactor
-contactor is happily humming
-confirmed fan not seized (spins smoothly)
there is no reset button i can see under the panel cover. if it matters, it's an Aire-Flo unit.
i was under the impression the low pressure switch would kill the compressor, but the fan would still turn on?
the only reason i suspect the capacitor is that all that's left (as far as i know) is the capacitor, compressor, refridgerant, and out of those, the capacitor is the cheapest and easiest to change :D . though, the capacitor isn't swollen, it's just rusted to crap.
so, any thoughts?
Gunguy45
06-27-09, 04:49 PM
Does the fan spin if you try to help it with a stick when it should be running? Do you hear the compressor running to humming?
If the cap is rusted then the wiring contacts may be as well. Cut power and clean up the winging connections.
Oh, when you get the cap, get a new contactor as well, cleaning the contacts will make them wear faster since the silver plating is probably degraded/damaged. It's ok to get one working again, but you need a new one.
If the cap is rusted then the wiring contacts may be as well. Cut power and clean up the winging connections.
Oh, when you get the cap, get a new contactor as well, cleaning the contacts will make them wear faster since the silver plating is probably degraded/damaged. It's ok to get one working again, but you need a new one.
di_rosa
06-27-09, 05:00 PM
the fan will spin freely if i move it with a stick
i do not hear the compressor running/buzzing, just the contactor
the terminals on the capacitor aren't corroded, just the body
makes sense about the silver plated contacts, i'll be sure to grab one, thanks
i do not hear the compressor running/buzzing, just the contactor
the terminals on the capacitor aren't corroded, just the body
makes sense about the silver plated contacts, i'll be sure to grab one, thanks
Gunguy45
06-27-09, 05:03 PM
I meant will the fan start and run if the contactor is closed? When the thermostat is calling for cooling?
I guess its possible you have an OPEN cap for both the fan and comp, but thats not NORMALLY the way they fail.
Do you have voltage on the OUTPUT side of the contactor when it is pulled in?
I guess its possible you have an OPEN cap for both the fan and comp, but thats not NORMALLY the way they fail.
Do you have voltage on the OUTPUT side of the contactor when it is pulled in?
daddyjohn
06-27-09, 05:13 PM
"confirmed power at the contactor"
As in you used a tick tester or a voltmeter? Like GG said, do have 240 volts at the load [output] side of the contactor?
As in you used a tick tester or a voltmeter? Like GG said, do have 240 volts at the load [output] side of the contactor?
di_rosa
06-27-09, 07:14 PM
yes, 240v at output side of contactor when the thermostat calls for cooling. i used a 3m meter from work to test.
no, fan will not spin when the contactor is closed.
no, fan will not spin when the contactor is closed.
daddyjohn
06-27-09, 07:21 PM
and the voltage at the motor leads is?
di_rosa
06-27-09, 08:06 PM
the fan motor? i never opened it up that far.
i guess what you're suggesting is check for a voltage drop between the contactor and the motor leads eh? and if there is, it's the capacitor
there were 4 wires going inside the center. should there be 240 at the motor and 240 at the compressor?
i guess what you're suggesting is check for a voltage drop between the contactor and the motor leads eh? and if there is, it's the capacitor
there were 4 wires going inside the center. should there be 240 at the motor and 240 at the compressor?
daddyjohn
06-28-09, 08:08 AM
Yes, they both use 240 vots. You should see 6 wires [maybe 7 if 4 go to the fan motor] going into the center of the unit. The 3 fatter ones are the compressor and the 3 [4]thinner ones are the fan motor. Touch the body of the fan motor; is it hot or the same as the outdoor temperature?