REPAIR BROKEN A/C TUTORIAL - Randazzo Heating & Cooling
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It happens to everyone. The hottest day of the year and the A/C quits working! No worries, though. With Randazzo’s step-by-step broken air conditioner tutorial we might have you up and running in no time with these few simple steps.

Be mindful that this page will only be talking about the split-system air conditioning units and air source heat pumps.

A few questions to ask prior to diagnosing what is wrong

When the thermostat is in the “Cool” position are the vent blowing any air at all?
If yes, is the fan on the outdoor air conditioner or heat pump spinning?
If no, the problem may not be with the air conditioner but with the thermostat or the furnace. See our write up on troubleshooting thermostats.

If the vents are blowing air, and the outdoor unit’s fan is spinning but no cold or cool air is coming out you might want to try and see if your furnace filter is clean. visit our post about determining if your filter is clean.  As stated on Lennox.

If the vents are blowing air and the outside (condenser) fan is NOT spinning try these next few steps.

Check your fuses or breaker in the main breaker box or fuse panel. Take note if the breaker is in the “tripped” or “off” position. If it’s tripped you can try the steps below.
Outside within sight of the air conditioner is the A/C service disconnect box. This is typically a grey colored box that houses the electrical connections to the outdoor unit. Often times you’ll see that the plug (switch) in the box can be flipped upside down or right-side up to allow the ac unit to be “on” or “off” and should be clearly depicted. Caution though, this is live electrical power! If you’re not comfortable or familiar with this type of connection, please contact Randazzo for an appointment. We’re licensed and insured for electrical and mechanical work. If you’re comfortable with the next steps please proceed.
If the breaker is “off” turn it on and try the system again. If it still fails read below.
Open the disconnect switch box and pull out the black carriage. You will see either two types of carriages. One style of carriage will have two “bullet-looking” fuses. If you have the fuses in your disconnect box then pull the fuses out of the carriage and take them to a store or anyone who can test for continuity in the fuses. Continuity is what determines a good fuse from a bad fuse. If you have a bad fuse it is best practice to replace both fuses with the appropriate rated fuses. It’s also a good idea to look at the tag or nameplate on the A/C unit and verify the maximum amperes the unit can safely handle. Do not mix/match fuses or over size fuses. Personal injury or permanent damage to the air condenser can happen. The other type of carriage will not have any fuses and will solely act as a lockout switch for the air conditioner.
Inspect inside the disconnect for and loose or damaged (burnt) wires. If everything looks correct you can put the disconnect back together and move on to the ac unit. Optional – If you have a multi-meter you can test each side of the disconnect to test for 110-120 volts of power or if you test both sides (legs) at the same time you should see 220-240 volts of power.  If you’re lacking power after these tests you’ll need to call Randazzo for an appointment or contact a local electrician. If all looks good then proceed to the next steps.
Inspect the control wires coming from the house to the a/c unit. There will be a copper line (liquid line), a copper line covered in black insulation (suction line), a metal or rubber-like hose (this the electrical whip and should be connected to the a/c disconnect box) and a thin control wire. The thin control wire is commonly cut or damaged by weed-whips or general landscaping. In a situation like this you’ll have to repair the damaged wire for the a/c to work again. If the wire is intact you’ll want to call for service. There are more advanced steps to troubleshoot however they involve opening the air conditioner up and diagnosing parts. If the a/c unit has any warranty left it will be best to have a professional perform the work as to not void any warranties.

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