A/C comes on for short time...


  #1  
Old 09-03-02, 11:44 PM
Databoy
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Unhappy A/C comes on for short time...

To whomever can help,

I have an AC unit (that I somehow left off of the home warranty), that will come on for a while, blows cold air, then the outside unit (compressor) shuts off. The thermostat is still on, the fan inside is still running, but the system now starts blowing warm air. The outside unit, is still on, but makes a nasty grinding/rumbling noise. I then turn off the system, cause it really sounds bad (like it is gonna blow - ok, maybe not that bad, but almost).

Something to note, that seems strange to me, is that my system is in 2 pieces. What I mean is, that there is the AC unit outside, and then a furnace unit inside. Do these two pieces work together somehow?

I am going to take a look at the unit outside, to see what I can find out. I have also bought a do it yourself book, but I don't know how far I will get. I will try and find out the information on my unit and post this info.

BTW, is it ok to answer other threads, if it is a been there, done that, kind of thing?

Thanks,

Data
 
  #2  
Old 09-04-02, 12:04 AM
Databoy
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Hey,

Just wanted to reply that the outside system has "Payne" on the top and "BDP Company" on the label. Also, it is a Model 42RCU108K.

It is a fairly open unit, with a compressor towards the side, a motor in the middle, and a giant fan on top (basically on top of the motor).

I stood outside and watched what happened, when it made the noise. Basically, the fan stopped moving and the noise was there.

Does this mean that I have a bad motor?

Thanks again,

Data
 
  #3  
Old 09-05-02, 12:47 PM
Databoy
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Well anyway,

I took the side panel off and found that all of the caps, switch, transformer, contacts, fuses, etc., appear to be ok. No apparent burning, corrosion or loose wires. I cannot see any obstructions.

I did however, notice that there is a small bell shaped housing, between my fan and motor. It appears real cracked and broken (it kinda looks like a small, broken, upside down flower pot.

I am pretty sure I have a motor issue now. Looks like I am going to figure this out all on my own. :-)

I have removed the big fuses from the power box thingy, so I am hoping I have no juice. I guess I should put a meter across the transformer, in order to see if I get any juice. I guess I could just check it by attempting to power it on, w/o the fuses in.

I only hope that someone has the motor in stock, that it isn't too difficult to remove, and that it actually works when it is put back together.

I do not think that I can go underneath and get the motor, so my guess is that I have to go at it from the top, by removing the circular fan guard.

Anyone?

Thanks,

Data
 
  #4  
Old 09-06-02, 10:48 AM
Databoy
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Bueller?,...Bueller?,...anyone?

OK, so now I know that I think I need a motor. :-)

I also contacted Payne, who did send a PDF file (4 pages), on the unit, and was told it might be hard to get replacement parts and they might be expensive.

I know I need a 1/4 PSC - 1075 motor. I am curious to know if all motors of that type are the same? Are they the same size and diameter? Do I need to worry about the AMPs?

I am assuming that the fan comes off and that I will need to trace where all of the wires go.

Is the power shut off to the unit, when I remove the big fuses from the fuse box by the A/C?

Data
 
  #5  
Old 09-07-02, 12:16 PM
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be sure

the fan motor is bad first. using an analog mulitmeter, check the common and fan terminals of the capacitor does the needle rise, then fall? if so, it is good. be sure you are getting voltage to the motor itself. if the cap is good, the motor is getting proper voltage, and still not working, replace the motor. same h/p, voltage, rotation. amps should be close
 
  #6  
Old 09-08-02, 09:23 PM
Databoy
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HVAC4U,

Thanks. I have 2 caps. I am guessing that when you ask me to check across the cap, you mean the one that belongs to the fan. Is that the larger or smaller cap?

Also, when I check voltage at the fan, where do I check? Are the wires that lead to it, connected to terminals?

Finally, when checking for voltage, am I going to have to turn this thing back on? Can I simply check for resistance (ohms)?

Thanks again,

Data
 
  #7  
Old 09-13-02, 10:02 PM
Databoy
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Hey,

I finally got it fixed. Thanks, HVAC4U.

OK, apparently the smaller cap belongs to the fan, and that was my problem. I had a guy come out and take a look at it and he found the cap. I do not have an anolog meter and maybe I could have got it done cheaper, but at least it is done and I am sooo glad it was not the motor and I did not just replace it.

It cost me about $100.00 (cap and labor). When the repair guy took out the cap, he showed it to me and the top had bulged out. He checked the cap and pressure and temperature and stuff. He told me that if I had checked with a digital meter for continuity across the cap, that I would have been able to tell if it was not bad (gone), but not if it was still good. When he put the new cap on, man did the fan RPM pick up.

For anyone who reads this, check the cap first.

Thanks.

Marcus
 
 

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