Problem has changed...

beckerhead · 08-04-2010, 06:57 PM

Hello all, this is my first post here so thanks in advance. I've been browsing through the site for 30-45 minutes and unable to find a problem like mine so I'll ask the questions.

Last night, my AC fan outside stopped working. I didn't notice it because the air return was drawing air, and I could hear the blower running from the attic. It started to warm up, and I went out side and the fan was not running. I did some online trouble shooting that said if you turn the air on, and hear a hum, try to spin the fan... if it comes on, then there is likely a capacitor problem... sure enough, I spun the fan and it fired up briefly. I killed it for the night (it was midnight). I came back this morning, replaced the capacitor, and away she went. I put my tools away and got the lawn mower going. Long story short, I fixed the capacitor problem several hours ago, and the temp in the house has not gone below 81 for 4 hours. I know that it is hot here in Houston (Heat index of 110 this afternoon) and I expect it to take a bit to cool off, but the air coming from the vents is certainly not 15-20 cooler than the air going into the return. I felt the lines outside the house going into the unit, and the large line is cold and the small line is hot. There is hot air coming from the fan so I know it's cooling something, but I cant get the air in the house to cool down to 73-76 where I usually keep it.

Any help is greatly appreciated.

yuri · 08-04-2010, 07:27 PM

Sounds okay to me. The unit may run for 8 hours to catch up. The maximum temp a unit is designed for is 100-110 degF so yours is maxed out. Have you washed the outdoor coil thoroughly with a garden hose/ NO pressure washer. If it is dirty it cannot get rid of the heat fast enough. Trim any bushes away so you have at least 18" clearance on the sides and none over top of the unit.

beckerhead · 08-04-2010, 07:53 PM

Ok, great, I appreciate that... My next question is this.. Can the polarity be reversed on the fan? It almost feels as if it is running backwards.... pulling air instead of pushing.

yuri · 08-04-2010, 07:57 PM

YES. It should suck in the sides and shoot out the top. Switch the 2 wires on the capacitor if it is running backwards.

**beenthere** · 08-04-2010, 08:53 PM

Yes. The fan can be running backwards.

Can be caused by you. If its a 3 wire fan motor, and you reversed the fan motor wires on it.

If the start winding in the fan is bad, that can also cause it to run backwards.

beckerhead · 08-05-2010, 01:19 AM

Well, it is now after midnight, and dark dark dark....The temp is now 75 degrees, and I will update tomorrow to make sure that it is still where it is supposed to be.

08-04-2010, 06:57 PM	#1
beckerhead Newbie Join Date: Aug 2010 Posts: 3	Problem has changed... Hello all, this is my first post here so thanks in advance. I've been browsing through the site for 30-45 minutes and unable to find a problem like mine so I'll ask the questions. Last night, my AC fan outside stopped working. I didn't notice it because the air return was drawing air, and I could hear the blower running from the attic. It started to warm up, and I went out side and the fan was not running. I did some online trouble shooting that said if you turn the air on, and hear a hum, try to spin the fan... if it comes on, then there is likely a capacitor problem... sure enough, I spun the fan and it fired up briefly. I killed it for the night (it was midnight). I came back this morning, replaced the capacitor, and away she went. I put my tools away and got the lawn mower going. Long story short, I fixed the capacitor problem several hours ago, and the temp in the house has not gone below 81 for 4 hours. I know that it is hot here in Houston (Heat index of 110 this afternoon) and I expect it to take a bit to cool off, but the air coming from the vents is certainly not 15-20 cooler than the air going into the return. I felt the lines outside the house going into the unit, and the large line is cold and the small line is hot. There is hot air coming from the fan so I know it's cooling something, but I cant get the air in the house to cool down to 73-76 where I usually keep it. Any help is greatly appreciated.

08-04-2010, 07:27 PM	#2
yuri Hvac Pro Join Date: Nov 2008 Location: Winnipeg, Canada Posts: 6,737	Problem has changed... Sounds okay to me. The unit may run for 8 hours to catch up. The maximum temp a unit is designed for is 100-110 degF so yours is maxed out. Have you washed the outdoor coil thoroughly with a garden hose/ NO pressure washer. If it is dirty it cannot get rid of the heat fast enough. Trim any bushes away so you have at least 18" clearance on the sides and none over top of the unit. __________________ "Cut it twice and it is still too short". To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. Last edited by yuri; 08-04-2010 at 07:31 PM.

08-04-2010, 07:53 PM	#3
beckerhead Newbie Join Date: Aug 2010 Posts: 3	Problem has changed... Ok, great, I appreciate that... My next question is this.. Can the polarity be reversed on the fan? It almost feels as if it is running backwards.... pulling air instead of pushing.

08-04-2010, 07:57 PM	#4
yuri Hvac Pro Join Date: Nov 2008 Location: Winnipeg, Canada Posts: 6,737	Problem has changed... YES. It should suck in the sides and shoot out the top. Switch the 2 wires on the capacitor if it is running backwards. __________________ "Cut it twice and it is still too short". To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

08-04-2010, 08:53 PM	#5
beenthere An old Tradesmen Join Date: Oct 2008 Location: PA Posts: 19,069	Problem has changed... Yes. The fan can be running backwards. Can be caused by you. If its a 3 wire fan motor, and you reversed the fan motor wires on it. If the start winding in the fan is bad, that can also cause it to run backwards.

Problem has changed...