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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7602
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Maybe u can help. Lennox 10ACB30-9P central AC. Works great but lately i've noticed

Customer Question

Maybe u can help. Lennox 10ACB30-9P central AC. Works great but lately i've noticed the compressor kicks on for a few seconds, then off...waits about a minute and kicks on again...usually stays on the second time...sometimes on a third try third try...Which should I change or both...Start capacitor or Dual capacitor? They both look like cake to change, just dont know which to do
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Unit is fully charged (has been checked)
Expert:  Phil replied 1 year ago.
Hello, This is not a capacitor issue at all.Do this for me please, after the system has been running stably for 5 minutes, feel the largest copper tube attached to the outside unit, the one covered with insulation, and tell me if its barely cool. sweating or frosty. So far I suspect that the unit might be slightly under charged (that is much better than over charged which is quite common), or that the refrigerant metering device orifice is partially restricted with dirt or chips of copper and copper oxide debris. Ask the technician to tell you what suction pressure the system is running when it stabilizes and the house is at 74F. I need the exact number, not an approximation.... and don't to feel the suction line for me. We can go from there
Customer: replied 1 year ago.
Cold, barely sweating. Closest analogy...like a cold beer right out of the fridge. Is that good? From what I gather you think I should have another service done on the unit and get the exact suction pressure? I had Horizon Services out last year and they "claimed" the unit was still perfectly charged (r22). of course they tried to tell me it was old and in need of replacement. Probably a scam im sure. What do you think? Thanks in advance, I really appreciate your help.
Expert:  Phil replied 1 year ago.
Hello again, thanks for the test.The refrigerant charge is real close to perfect, it is not undercharged enough to cause the short cycling by itself. You will not learn much from a second service. This problem of false starting is not entirely uncommon, if it only has to make two attempts before it stays running, it is likely that the low pressure switch is tripping prematurely. I would try fitting a jumper wire across the low pressure cut out switch. if that stops the short cycling we know that the switch is the cause most likely. You can find it marked on the wiring diagram glued to the inside of the condensing units service panel. I would not replace the switch because the refrigerant in the system has to be removed to do it, and because that is very expensive and because those switches are non adjustable. I would simply ask the tech to install a Penn or Ranco brand adjustable low pressure cut out switch and attach it to a flare tee, fit onto the 1/4" suction service port... and set the control to cut out 45 psig, and to cut in at 62 psig.. that should stop the short cycling while still providing low pressure protection. The tech can see if that works or not, if not he will want to set the cut out a bit lower than 45 psig.http://screencast.com/t/cVdYht6WWOh0 ------------We are on the honor system here. Please remember to rate my service before you leave today. It is how I earn a living, and does not increase your charges. If you need anything else, just let me know. You can continue asking follow-up questions at no additional cost..
Customer: replied 1 year ago.
What are your thoughts on a "hard start kit", some additional capacitor thing, I have had recommended. band aid on a bigger problem or the ghetto fix?
Expert:  Phil replied 1 year ago.
If the compressor is attempting to start. but not actually starting... just humming heavily for 2 or 3 seconds... then a hard start kit will be a very good idea and will solve the problem. If however the compressor is starting and running for 15 seconds to a minute or longer, then it IS starting and running, and a hard start kit will not solve that problem... it would be a pressure switch problem that we would need to investigate as mentioned earlier. Tell me in seconds how long it 'runs' or humms heavily before it eventually starts... if it is only for 2 or 3 seconds, you will be right on track with a hard start kit.
Customer: replied 1 year ago.
Hmmm...its more of a buzz when it first starts. Goes away in seconds once it's spinning or whatever it does and sounds normal. But there are times when it runs for a minute or two and then shuts off. waits about a minute or two and then kicks back on. buzzzzzzzz normal sound... Have a friend who knows these things better than me. May try the hard start kit first as they don't cost much @ all. Worst case, I've already priced some low pressure cutout switches and im sure he could install one of them too. Will keep you updated. Thanks Phil
Expert:  Phil replied 1 year ago.
Thats a good plan, let me know how it goes....... We are on the honor system here. Please remember to rate my service before you leave today. It is how I earn a living, and does not increase your charges. If you need anything else, just let me know. You can continue asking follow-up questions at no additional cost.