Posted: 4/3/2014 3:19:11 AM EDT
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I'm hoping someone here can help me diagnose and fix an issue I'm having with my residential AC. It's getting warm...
My house is not cooling because I suspect the indoor fan/blower is not pushing air out of the vents. We have changed all air filters and did not get any relief. The outside unit is on, I can hear it getting power, and I've noticed that the coolant line is frozen. I suspect the line is getting frozen since the inside unit isn't moving any of the hot air across a heat sink and the coolant isn't giving up it's cold. 
I've checked all the electrical and nothing seemed wrong. Any advice on what to check for? |
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No air being pushed out of the vents means your fan isn't running.
If your fan isn't moving air across the coil, you'll not get the proper BTU absorption into the coolant. Coolant doesn't absorb BTUs, you may be pushing liquid through the compressor and into the condensing unit outside (frozen line). |
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If the blower isn't running on the air handler parts, it'll freeze up fast. You need to find out why the inside unit isn't coming on. It could be as simple as a bad capacitor on the motor, or it could be a bad motor or a bad control board. Put your T stat fan switch over from auto to on and see if the blower kicks on. If it does, it'll likely be a board issue, if it doesn't, It'll likely be a cap or blower motor issue. Easily checked by seeing if you have 120 to the motor on a call for cool. If you have 120, check cap first to make sure it's within 6% of rated specs, if it is, then replace motor AND cap.
And turn off outside unit, you're going to kill the compressor if keeps passing liquid. |
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The indoor fan will not push air with the thermostat on auto or ON. So it's looking like I've got to climb into the tiny attic and start poking around with a well insulated stick.
Quoted:
Start simple... Are your filters clogged? read mo betta  [/sarc] the filters aren't clogged, but they may have gone two weeks too long before we changed them about a week ago. Can dirty filters cause the indoor fan motor to give up?
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Quoted:
The indoor fan will not push air with the thermostat on auto or ON. So it's looking like I've got to climb into the tiny attic and start poking around with a well insulated stick. read mo betta [/sarc] the filters aren't clogged, but they may have gone two weeks too long before we changed them about a week ago. Can dirty filters cause the indoor fan motor to give up?Quoted:
The indoor fan will not push air with the thermostat on auto or ON. So it's looking like I've got to climb into the tiny attic and start poking around with a well insulated stick. Quoted:
Start simple... Are your filters clogged? read mo betta [/sarc] the filters aren't clogged, but they may have gone two weeks too long before we changed them about a week ago. Can dirty filters cause the indoor fan motor to give up?Blower will still run if filters plugged, it'll make it work harder but 2 weeks late on a filter change isn't really a big deal if the filters were not plugged badly. Now you need to find out where the 120V stops..... |
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First make sure the evap coil isn't frozen over and preventing airflow. Turn thermostat off, but leave fan on, that'll thaw the evap in an hour or two depending on ambient temp.
If the coil was frozen over, you more than likely have a low charge, unless you were running the AC with low temps outside(most home units don't have head pressure controls and will freeze up if run at low ambient temps) If there is no airflow after a couple hours of running the fan alone in manual, the fan isn't running, time to grab the multimeter and check things up top. Also, check the easy things first, see if you have 120v to the air handler, then if the proper connection at the fan(might have several speeds/leads) If so, check the capacitor, and ohm the fan motor. |
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I've been up in the attic for a while now, and I can't seem to locate the fan electrical. I did cut power to the unit and poked around, nothing looked burned up. I am beginning to think that it's not the indoor blower actually, since I could hear it kick on when I turned everything back on, but there's still no air (warm or cool) coming out of the vents. The frozen line/coil is beginning to seem more plausible.
I'm glad work has AC, feel bad for my GF, it is supposed to be 86 today 
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Quoted:
I've been up in the attic for a while now, and I can't seem to locate the fan electrical. I did cut power to the unit and poked around, nothing looked burned up. I am beginning to think that it's not the indoor blower actually, since I could hear it kick on when I turned everything back on, but there's still no air (warm or cool) coming out of the vents. The frozen line/coil is beginning to seem more plausible. I'm glad work has AC, feel bad for my GF, it is supposed to be 86 today Could be a coil that has completely frozen, but air will usually move around the coil. I've never seen one completely seal off. If the coil is a block of ice, your defrost cycle isn't happening. That could be a couple of things, depending on how your defrost is programmed. (I still doubt this considering a complete lack of air flow from the registers.) If you "hear" the fan humming, it may be that it's getting power but the start capacitor is done and the blower fan just can't get moving. That's a common issue and is easily fixed. Be careful if you replace the capacitor as it holds a charge and it will bite you if you're not careful. |
| When you changed filters, did you happen to switch to the "Super Duper MERV-1000 Ultra HEPA Pleated " filters? The filters that are so effective they catch sub-atomic particles can be pretty restrictive, especially when they start to gather dust. I just use a plain media filter and change it regularly. |