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Mark Henley
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3217
Experience:  UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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My air conditioner for my house wont start up

Resolved Question:

It makes the same noise over and over again but won't actually stay on. Sounds as if it is trying to start but can't, could it be a relay or something.
Submitted: 5 years ago.
Category: HVAC
Expert:  Mark Henley replied 5 years ago.

Hi,

 

It sounds like the compressor is either over heating or the unit is shutting off on a refrigerant pressure control ( either high pressure or low pressure ) .

 

Does the outdoor unit fan come on at all when it is trying to start ?

 

Thanks

 

Mark

 

 

 

Customer: replied 5 years ago.
It tries for about 15 min, a quiet humming noise, not continous it starts and stops ovr and over, and then you hear the air conditioner noise with the fan kick in but then switches off streight away and then the humming noise over and over again
Expert:  Mark Henley replied 5 years ago.

Hi,

 

It sounds like you have a bad contactor in your outdoor unit. It looks like this one.

 

graphic

 

Thanks

 

Mark

Customer: replied 5 years ago.
I have had a look on the weekend but did not see that contactor, where would I find it and what does it do. Is it a big problem and how do I go about repairing it, what causes this, the fact that it is trying to start, does that mean that the whole air con unit doesn't need to be replaced. If that is the problem what could I expect to pay +-. I know that is a lot of questions, I am sorry. I just need some news good or bad.
Expert:  Mark Henley replied 5 years ago.

Hi,

 

From what you describe it sounds like a contactor problem. If it were a compressor problem the fan should stay running the whole time that you hear the humming noise. So I'm discounting that it may be a compressor problem however it could be but it just doesn't sound like it right now from the symptoms, there is also another possible defective part which is the capacitor.

 

In your situation it will be worth having a service call to have it checked as there is a good possibility that you won't need a large item such as a compressor. A capacitor or a contactor are the two most inexpensive repairs that can be made on a unit.

 

Thanks

 

Mark

Customer: replied 5 years ago.
One more thing, when it makes the initial start up noise there is a click heard then it stops and this carries on the whole time, can this damage the unit and is there a chance it may just start up if I leave it. Or should I kill the main switch. thanks for your help and you fast response.
Expert:  Mark Henley replied 5 years ago.

Hi,

 

No , I would kill it in case it is the compressor not being able to start because of the capacitor. There isn't much chance that it is going to start if either of those components have failed, or even if it is the compressor.

 

Thanks

 

Mark

Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3217
Experience: UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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Mark Henley
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HVAC Controls DDC
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UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential