I noticed that my house ac is not working today. I checked the circuit breaker first, it was not tripped. The thermostat is on "cool". The blower is blowing. Outside, the air conditioner is doing nothing. The outside unit is just under 3 years old, still under warranty. Any simple things I can check before I call a pro?


Lawrenceville, GA

Is there air coming into the house? Sometimes the vents can freeze up. Chuck

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Manchester, New Hampshire

Well, I feel room temperature air is blowing at the vents.

Oh, and it has been working this Summer, or Spring, whatever season it is.


Lawrenceville, GA

You might check that the condensate drain isn’t stopped up.  My unit has a sensor that shuts down the compressor if the water level gets too high.  Another thing to look for are ants within the electrical panel on the outside unit.  Ants do like the relays.

Lorena, Texas (South of Waco)

It could be your ballast resistor on the outside unit.  It is about an $18 part. This connects inline between the power coming in and the compressor and fan motor.  It is kinda like a jump starter to get these units going.  It will be a metal canister around the size of a pack and a half of cigarettes with wires coming in and out.  You can check to see if one end is pushed out.  Both ends should be flat but the liquid inside can expand and pop the end out.  Whatever it is should be covered under your warranty.

Dan

Ok, I was the town electrician, not the hvac guy, but I've been thru this at my house more than once. I can't help with the pressure/ charge side, hooking up the gauges, etc., but at 3 years that should be ok. I'm going to assume you know how to safely go in with a volt meter, or better yet a modern meter or old fashioned solenoid tester (a wiggins). Don't get hurt, even 110 on one side will kill you.



There should be a disconnect at the unit (an off on switch). Door should only open in off. Check the voltage there, 120 to ground each side, and 220 between them. Voltages are nominal, could be 110-120, and 208-240. If theres fuses, check them with an ohm meter, they should be de-energized in the off position, but the top hardware is hot, and easy to get across if you reach in to pull them.



Somewhere in the unit, typically in the air handling unit in the house if its a split system, there is a control fuse that feeds 12-24 volts to the t- stat and controls. Might be a glass fuse, but my new unit uses a modern automobile stab, plastic fuse. Some tstats give an error, or AC OFF-if this blows, but not all (or mine). It will be in an easy off access panel, in a circuit board, and hooked up with small, like 22 gauge, wire. Most of the time, thats where my problem is. Don't know why, but IMHO, they let the HVAC guy run the wires, instead of me.



After that, I call the guy who knows what he's doing, and stand around and try to learn something so I can do it next time.



Be careful, I've lost qualified friends who quit respecting the current.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

This morning I did a test before I left for work. When the system is on and in cool mode, I can hear a hum at the unit outside and nothing else. When I turn the system off, there is no hum.


Lawrenceville, GA

Is the fan spinning on the air intake?

Sometimes they stick over the winters. Use a long screwdriver to set the fan blade in motion-BUT BE CAREFUL !!!!!!!!!!!!!!!!!!!

Mine did the humm routine both last year and this year.Once I got the fan to spin the A.C. was O.K.

Oldmics

Do not leave the thermostat on, turn it off until you get the unit fixed.  That hum you are hearing is the compressor and it will overheat.  As the previous post suggested, try spinning your fan with a long piece of something.  It sounds like either the ballast resistor is bad (most common in my limited experience), the fan is bad or the compressor is bad.

Dan

Do not leave the thermostat on, turn it off until you get the unit fixed.  That hum you are hearing is the compressor and it will overheat.  As the previous post suggested, try spinning your fan with a long piece of something.  It sounds like either the ballast resistor is bad (most common in my limited experience), the fan is bad or the compressor is bad.

Dan