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-   -   compressor wants to start but won't (http://www.diychatroom.com/f17/compressor-wants-start-but-wont-73816/)

wetbar 06-16-2010 12:49 AM

compressor wants to start but won't
 
Hey I have a unit that had no freon in it. I checked and found a hole in the lines. I repair the leak and put about 1.5 pounds of freon in it. I also added a super start cap to the comp. You can hear it wanting to start but will not start - even with the extra cap. Is this thing just locked up and bad? There is a low pressure switch on the unit, so I would think it shut the comp off before damage was done. How do I get more freon in the unit if the comp wont run?

Thanks for the help.

biggles 06-16-2010 05:07 AM

did you have oil around that leak you repaired?if so might need a cup of refer oil if you pulled a vacuum you would of been easier to go right to the liquid line flip the can of freon and let it fill the LL up then start it.if you give the compressor contactor a quick push in does the compressor run?..if it humms it is locked up

beenthere 06-16-2010 06:16 AM

Did you pull a vacuum on the system before you tried to put refrigerant back into it?

wetbar 06-16-2010 07:04 AM

I did not see oil around the hole. I did pull a vaccuum, and it held for at least 20 min. The compersor will click in then click out, but it does not hum. The contactor stays in but it will not run.

hennyh 06-16-2010 08:32 AM

Quote:

Originally Posted by wetbar (Post 457014)
The compersor will click in then click out, but it does not hum. The contactor stays in but it will not run.

Are you sure the capacitor arrangement is correct?

I'd return the capacitor arrangement to the way it was right before the leak and see if it runs.

Why does a simple leak repair require a "super start cap"?

If the contactor is staying engaged then what's clicking in and out? Is it the starting relay?

wetbar 06-16-2010 08:43 AM

no the compressor tries to kick on, when it can't it clicks off. Yes the cap is going across the brown herm and the common of the cap.

hennyh 06-16-2010 09:07 AM

Quote:

Originally Posted by wetbar (Post 457038)
no the compressor tries to kick on, when it can't it clicks off. Yes the cap is going across the brown herm and the common of the cap.

I would pull the disconnect and make sure the LV control system is functioning 100% correctly. Does the contactor stay engaged?

If not, will it stay engaged with pressure switches bypassed?

Now remove the extra cap (ie return it to stock condition where it was known to be running fine) and re-connect the disconnect and see what happens.

If the clicking out is the actual contactor then I'd think the problem is the protection circuitry (LP, HP, etc) or the contactor itself.

Could the original cap be bad if it's still in the circuit? I don't think your super start cap will function properly if it's in the circuit with a bad cap.

What kind of system is it? How long did it sit without refrigerant? How old is it?

Can you ohm out the compressor?

Good luck

wetbar 06-16-2010 12:06 PM

The contactor is working corectly. It stays in all the time. The fan runs all the time. It sat without freon for at least 3 days and the unit is 6 years old. I have not tried ohming the compressor yet.

wetbar 06-16-2010 01:05 PM

Ok I'm here now. Cap is good but I put a new one on. Contractor is pulled in, it tries to start and bums. Hums for 5 seconds that shuts off. Tries again to start and Hums for 5 sec then cuts offf

There are 4.1 oh in-between the common cap wire and the blue wire going to compressor. 3 ohms between same blue wire and ground (black wire from compressor),and 1.1 between the cap common and the black ground.

beenthere 06-16-2010 04:40 PM

There is no ground wire on the compressor.

Your ohms add up as they should.

Did you use a scale to determine that you only put 1.5 pounds of refrigerant in the system?

wetbar 06-16-2010 06:04 PM

yes I used a scale. then when I pulled out the freon I used a scale again and it measured the same 1.5. The black wire goes the the contactor, I said ground but yeah it is the other side of the 240 V. The one thing I did not do is remove the black wire from the contactor before I measures the resistance.

Marty S. 06-16-2010 06:36 PM

Check the amp draw when it tries to start. If it's wired correctly, not liquid slugged and the capacitor is good then you have a locked rotor.

wetbar 06-17-2010 12:28 PM

Check the amp draw on what wire? what does locked rotor mean?

Marty S. 06-17-2010 06:15 PM

Common wire on the compressor,almost always black colored. Locked rotor means the compressor is seized. Look on the units name plate for the LRA rating.


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