AC compressor help please

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Old 06-27-14, 09:27 AM
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AC compressor help please

I have 2 units on my house. Last year, the upstairs unit stopped working. It turned out to be the capacitor and I saw a repairman fix the issue. 2 days ago, the downstairs unit stopped cooling. I looked at the outside unit and the fan wasn't running. So I went and bought a replacement capacitor (same size, rating, etc). Replaced the capacitor and the unit kicks on now. However, it isn't cooling. It was cooling prior to the unit not kicking on.

Before I call a repair person, I'd like to try and figure this out myself. I can't tell if the actual compressor is kicking on. It sounds the same as the other unit, but the fan is so loud that it is hard to hear the compressor. Would it be safe to not connect the fan to the capacitor and turn it on to see if the compressor turns on?

Any other advice? Air is blowing, the fan is running, but it isn't cooling.
 
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Old 06-27-14, 09:52 AM
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Yes you can disconnect the fan, but don't let the comp run very long with the fan off.
 
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Old 06-27-14, 09:56 AM
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Did the capacitor you replaced have two or three terminals on it ?
 
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Old 06-27-14, 10:02 AM
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It had 3. It's a dual start. I wired according to the wiring diagram. I've already gone out and made sure the connections were solid.
 
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Old 06-27-14, 11:08 AM
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I removed the brown wire from the capacitor (says fan on the capacitor and wiring diagram shows the brown wire going to the fan). I started the unit and the compressor turned on. It actually turned the fan at just about normal speed. I'm assuming this is normal. So this probably isn't an issue with the capacitor or the compressor. I'm assuming I need to get someone out now? Any other advice?
 
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Old 06-27-14, 11:53 AM
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Reconnect the fan..... start the unit cooling.

Is there hot air coming out of the top of the unit ?
Check the copper lines connecting the compressor to the air handler...... The larger one should be very cold and usually insulated...... is it ?
 
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Old 06-27-14, 12:51 PM
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So the fan ran with the brown wire disconnected?
 
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Old 06-27-14, 01:10 PM
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Yes, the fan ran without the brown wire connected.
 
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Old 06-27-14, 01:18 PM
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PJmax, I will check that. Thanks.
 
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Old 06-27-14, 06:00 PM
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So it is blowing fairly cool air out the top (not hot air like the working unit) and the copper line is cool but not cold like the working unit.

The capacitor I replaced had 3 caps. A green for the fan with 2 terminals on it. A white for the HERM with 3 terminals on it. And a black with 4 terminals on it. The one I replaced it with had 3 caps. 1 white one with 4 terminals that said HERM. 2 black ones, each with 4 terminals. One said C and the other said FAN. I'm assuming it doesn't matter which terminals I put the connectors on, right?

So I just tried again and removed the brown wire. The brown wire definitely goes to the fan along with 2 other wires. One of the wires from the C also goes to the fan. The other wire from the C goes to a contactor. The yellow wire definitely goes to the compressor. With the brown wire off, the fan still started. So I actually can't tell if the compressor is coming on or not. I removed the yellow wire and put the brown back on and the fan came on as well.

Is that normal that the fan can run without being connected to the capacitor? Is it possible I have a bad capacitor? I'm really not sure what to do from here.

Here is the wiring diagram from the inside of the panel.

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Last edited by PJmax; 06-27-14 at 06:15 PM. Reason: changed posts to terminals
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Old 06-27-14, 06:11 PM
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To shut the fan off..... remove black from the contactor or violet and brown from capacitor.
Normally if you remove just the brown wire the fan will just sit there and hum.
 
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Old 06-28-14, 09:59 AM
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It turned out to be worst case scenario for me. The compressor is on, but it isn't circulating the freon. So looks like a new unit for me. It is 10 years old.
 
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Old 06-28-14, 10:08 AM
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I wouldn't pull the plug on it yet. How do you know that there is no flow?
 
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Old 06-28-14, 12:19 PM
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The technician from a company I trust determined that. I saw the gauges as well.
 
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Old 06-28-14, 12:41 PM
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Was there pressure on the gauges?
 
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Old 06-28-14, 03:00 PM
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One showed pressue the other didn't (the low).
 
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