Links for Troubleshooting Inoperative AC


  #1  
Old 02-25-01, 07:06 PM
Bart Beaudin
Visiting Guest
Posts: n/a
Question

Our central air conditioning system (Sears compressor unit outside) hasn't cooled for 15 years. Do you know of any links to help me troubleshoot the problem? I want to sell my home this summer and would like to get it operational.

Thanks for any suggestions!

 
  #2  
Old 02-26-01, 02:21 PM
PDF
Visiting Guest
Posts: n/a
You should

Call in a TECH.But do to the age of the unit,and it hasn't run for 15 years,tells me that it is time for a replacement.PDF
 
  #3  
Old 02-26-01, 02:48 PM
Guest
Visiting Guest
Posts: n/a
Try the obvious first. Is there power to the unit? If so, is the fan turning, is the compressor running? If no power, check breaker/fuses and get power to the unit. If power to the unit and it still doesn't run, check that the contactor is pulling in whent he A/C is on at the thermostat and the set point on the thermostat is below the room temp. You may want to have somebody turn the unit on and off at the thermostat while you stand at the condensing unit outside and listen for the contactor "snapping in". If no "snapping" check that the furnace/air handler has power and that you are getting 24volts to the condensor. If this is ok, try manually pushing the contactor in. (Be very carefull doing this, there should be 240volts present) If the unit starts and cools, you need a new contactor. If running but no cooling you will need it serviced.

Hope this helps you get started. Let us know what you find.
 
  #4  
Old 02-26-01, 03:35 PM
Bart Beaudin
Visiting Guest
Posts: n/a
Question Source for Schematic Diagrams for Sears AC?

Thanks ... Dmeyer for your preliminary testing instructions to check-out my Sears Central Air Conditioning Unit.

Where can I find the schematic diagrams for a
Sears Roebuck Model # 769.81127 (Custom 600) central air conditioning system?

Hope you can direct me to a source.

Many thanks...Bart from Colorado (Little too cold to work on it today!)
 
  #5  
Old 02-27-01, 02:58 AM
PDF
Visiting Guest
Posts: n/a
Bart

The diagrams should be inside a panel of your inside blower or a panel in the condensing unit outside.You will need a volt/ohm meter that can also check amp draw.Meter should be ditgital.Make sure you install gauges to check for refrigerant in system.If unit is equipped with a low pressure cutout it will not start.PDF
 
  #6  
Old 02-27-01, 10:25 AM
Bart Beaudin
Visiting Guest
Posts: n/a
Question Ammeter Range and Types of Gauges for AC Troubleshooting

Thanks PDF for your comments!

Would my 10 Ampere range on my multimeter be sufficient for measuring current?

What type of gauges do I need to buy (or rent) to check the refrigerant in the system?

Many thanks...Bart
 
  #7  
Old 02-27-01, 02:41 PM
PDF
Visiting Guest
Posts: n/a
Hey

If the compressor is drawing LRA (Locked rotor amps) which means it could be seized it will bury the needle on your 10 amp meter.If it is LRA,the amps could be as high as 40.If you find the wiring diagram see if it incorporates an LP control or low pressure control.Remove the 2 leads from it and ohm the control.If it shows continuity you have at least some gas in the system.You cannot rent gauges and to buy them will set you back a bit.Please check with friends or relatives to see if they know someone in the business.Please take care and remember you will be working,in some cases ,with 220 volts.PDF
 
  #8  
Old 02-27-01, 06:58 PM
Guest
Visiting Guest
Posts: n/a
Be careful of the EPA fines ($25000.00). If you vent refrigerant or are not certified to handle refrigerant you may get in big big trouble. Be careful of the 220 volts also.
 
  #9  
Old 02-28-01, 07:02 AM
Guest
Visiting Guest
Posts: n/a
I would recommend that you do not mess with the refrigerant. As I stated earlier, if you force the contactor on and the compressor runs, (you should be able to hear a running compressor versus one that is just humming. The humming would indicate a frozen compressor which is usually bad.) your problem is in the 24volt control circuit or in the refrigerant charge. If you have a low pressure cut-out switch and the compressor runs when the contactor is pushed in, by-pass the switch and see if the unit runs. If so, you either have a low charge or your switch is bad. At this point you need somebody to check the charge and/or replace the switch. The reason I said not to mess with the refrigerant is because even if you were to find that it is low, where are you going to get R-22. You need to be EPA certified to handle this refrigerant and it is in your best interest to find the leak before charging so you don't vent the refrigerant. You also need to know how to determine the proper charge.
More info for you to chew on!
 
  #10  
Old 02-28-01, 09:35 AM
Bart Beaudin
Visiting Guest
Posts: n/a
Exclamation Thanks for Counsel on AC Troubleshooting!

Thanks to "dmeyer", "PDF", and "Christopher" for your guidance. My original plan was to do as much as I personally can to troubleshoot the system and then call in a service company. I will definitely not touch the refrigerant systems!

Many thanks...Bart
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: