Need Advice/help With Central Air

[engineered_excellence]

Before I call the service man out, I wanted to see if I could figure out what is wrong myself.

 

 

My Central AC/furnace is one year old, just recently the outsider condenser unit hasn't been kicking on, the furnace blower kicks on, and I'm getting air flow, just not cold.

 

It will work sometimes, like after I turn the breaker on and off, and mess with the programmable thermostat. But that didn't work the last two days. I have tried using the programmed mode, and also just the manual "on" mode, doesn't seem to make a difference.

 

There is one wire going from the furnace/ac unit in the basement to the condenser unit outside, along with the refrigerant pipe. I am guessing my problem lies on either end of this wire, like an internal thermostat, or whatever it is that kicks on the condenser. Any suggestions? Or should I just call the experts.

[Mememe]

if it works after being shut off for most of the day, something is probably freezing up. You may also have a clogged condensation drain. Turn off the AC until tomorrow. When you turn it back on, let it cool the house by 4 degrees and stay there for an hour. Lower it 4 more degrees and repeat. Don;t try to go too fast or it will just freeze up again. If it still won't work, call an HVAC person.

[boroboro]

If you're capable and motivated you might be able to debug the problem with the unit's wiring schematic and a multimeter. I've occasionally had to debug failed A/C units in the course of a business I used to run. Sometimes I found it surprisingly difficult to figure out what was going wrong. Sometimes it's easy, though -- check the wearable components like switches and relays first.

 

I'm no HVAC expert, but I used the diagrams by following what I wanted the unit to do. For example, If I want it to turn on and it doesn't, I start with the 'on' switch on the wiring schematic, and check and follow the wiring and signals from there to the part that isn't turning on.

 

Checking refrigerant levels and pressures looks like a pretty involved job, involving specialized tools and knowledge. I haven't gotten into that yet, and hope I don't have to very soon...

 

Like Mememe mentioned, icing is a possibility also. I'm very fond of my new 24k mini-split heat pump, but it can ice up in high humidity conditions. If I turn it on full cooling mode in a hot humid room, it will cool very well for an hour or so, then not so well, than not at all. The unit, pumps and fans keep working, just no cold air. Poking around inside the indoor unit, I eventually discovered an inch of ice covering the entire evaporator. Since then I've learned that it works great in a stable environment, it just doesn't like to cool off a large volume of hot, humid air.

 

Be careful if you check out the wiring and internals! There are probably exposed, live 120V / 240V components inside.

[Kingdiamond]

Do not go into wiring on any AC unit if your not familiar with wiring its very dangerous let the heating cooling guy do that .

[Christopia]

Change your furnace filter, get the cheap blue ones. You are probably icing the condenser due to low air flow caused by a poor flowing or dirty filter.

 

What he said! Cheap-o filter in the summer, expensive one in the winter. My high eff. did the same thing first summer I ran it, we installed it in the fall. My buddy that does havac laughed like hell, said he was waiting for my call. HE knew it was gonna happen, lol

[engineered_excellence]

Thanks for all the help guys, Hopefully its something as simple as changing the filter or unplugging the condensation drain.

[Guest Happy Guy]

If it does it mostly only on the hottest time of day there may be a overheat shut off. Make sure the cooling stuff on it is clean and there is easy air flow around the unit. That is one of the only things you could do yourself. With it being only one year old and under warrantee just clean things up and then call a service man.

[+Dizledot]

Mine was a bad condenser. Depending on the manufacturer there was a run on bad ones which just happened to be the one I had. Because of the malfunction my bill for the month before we realized it was bad was through the roof. The unit wasn't cooling but the thermostat was calling for it to cool but no cool air so it ran a lot! There are also switches that are on the unit that just plug in that can go bad also....much cheeper fix but wasn't my issue. I do know mm friendly heating and cooling company if you are in my area. Pm me if you want details...I have no professional, personal or financial relationship to the company. They are good people who mind their own business.

[jayt]

Before I call the service man out, I wanted to see if I could figure out what is wrong myself.

 

 

My Central AC/furnace is one year old, just recently the outsider condenser unit hasn't been kicking on, the furnace blower kicks on, and I'm getting air flow, just not cold.

 

It will work sometimes, like after I turn the breaker on and off, and mess with the programmable thermostat. But that didn't work the last two days. I have tried using the programmed mode, and also just the manual "on" mode, doesn't seem to make a difference.

 

There is one wire going from the furnace/ac unit in the basement to the condenser unit outside, along with the refrigerant pipe. I am guessing my problem lies on either end of this wire, like an internal thermostat, or whatever it is that kicks on the condenser. Any suggestions? Or should I just call the experts.

 

Your furnace tells the a/c compressor to turn on. When the thermostat calls for cooling a relay in the furnace sends 24 volts out to the compressor. In the electrical compartment there is a contactor, basically a electric switch, which turns the compressor on. You can test to see if the contactor is getting 24 volts. The 24 volts is carried to the contactor on the small wire that runs with the "refrigerant pipe". If you have 24 volts on that wire at the contactor the next thing to test is for 240 volts coming in to the contactor. If you don't have 24 volts on the contactor coil then most likely your thermostat is bad. Use a volt-meter to test from one lug to the other, side to side, and make sure you have 240 volts. Test the top first that will be the incoming power, test the bottom second and that will tell you if power is making through the contactor. The contactor could be bad they are pretty cheap to replace, I think about $20. There could be other more costly problems but these are your most common.

 

I'm assuming that you have actually gone outside and looked at the compressor and the fan is off and the unit is not making any noise?

 

Like the others have said you could be icing up the evaporator coil inside the furnace duct, that usually occurs when the unit is running for a while. It can be both the result of low air flow and low refrigerant.

[engineered_excellence]

Your furnace tells the a/c compressor to turn on. When the thermostat calls for cooling a relay in the furnace sends 24 volts out to the compressor. In the electrical compartment there is a contactor, basically a electric switch, which turns the compressor on. You can test to see if the contactor is getting 24 volts. The 24 volts is carried to the contactor on the small wire that runs with the "refrigerant pipe". If you have 24 volts on that wire at the contactor the next thing to test is for 240 volts coming in to the contactor. If you don't have 24 volts on the contactor coil then most likely your thermostat is bad. Use a volt-meter to test from one lug to the other, side to side, and make sure you have 240 volts. Test the top first that will be the incoming power, test the bottom second and that will tell you if power is making through the contactor. The contactor could be bad they are pretty cheap to replace, I think about $20. There could be other more costly problems but these are your most common.

 

I'm assuming that you have actually gone outside and looked at the compressor and the fan is off and the unit is not making any noise?

 

Like the others have said you could be icing up the evaporator coil inside the furnace duct, that usually occurs when the unit is running for a while. It can be both the result of low air flow and low refrigerant.

 

Thanks, this is the answer I was looking for, I'm gonna go check it out.

 

*EDIT

 

I don't have a voltmeter, but I opened the panel on the condenser and when the thermostat kicked the AC on, the contactor switch engaged, and the condenser was humming but not operating, and when the thermostat turned the AC off, the contactor switch disengaged. I guess I'm gonna call the service-man out. Might have to buy a new bottle of febreeze for the basement..lol.

[Beans]

Check your breakers and possible fuses in the disconnect by the condensor

 

The humming sounds like the 220volt is missing

[jayt]

Did the fan turn on? The humming could be the contactor. It's pretty common for them to hum a little. You might have a tripped breaker or a blown fuse at the disconnect for the compressor like Beans said.

 

If the contactor is engaging then the problem is outside not inside.

[Morhawk]

Definitely check your circuit breaker, A/C units will have a humming sound and not turn on if the breaker is popped. Speaking from experience and a lot of WTF'S?! lol