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AC Compressor © D Friedman at InspectApedia.com Air Conditioner / Heat Pump Diagnosis Details

Detailed Diagnostic & Repair Procedures

Air Conditioner or Heat Pump Diagnostic Procedures List.

For each component in an A/C or heat pump system that might have failed, this article lists articles useful to diagnose and repair the problem.

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Major Areas to Investigate for Problems With Air Conditioning Systems & Equipment

For air conditioner or heat pump troubleshooting that can be done by many building owners or occupants,

Start Here: DIAGNOSTIC GUIDE A/C or HEAT PUMP - quick easysteps to diagnose an air conditioner or heat pump.

Or for more detailed troubleshooting and procedures used by trained HVAC repair technicians, can see our list of detailed diagnosis and repair procedures given below.

A/C Heat Pump Repair Topic Areas

Air Delivery: Supply & Return Ducts

The air conditioning system operates, both indoor blower and outdoor compressor are running, but the does not produce cool air, or not enough cool air: see

The air conditioning system operates but there is not enough cool air flow at the registers: see these diagnostic guides:

Air Filters

Air Handler Unit

Inside cooling or evaporator coil defects

that can be seen by eye: dirty coil, blocked coil, frost on the coil, improperly sized evaporator coil, improper evaporator or cooling coil placement in the system.

Air flow across the air conditioning evaporator coil:

if airflow is weak for any reason (dirty coil, duct system defects, blower fan defects, dirty blower squirrel cage fan), the air conditioning system will not operate properly.

Some experts write that there should be between 350 and 400 cubic feet of air per minute (CFM) moving across the evaporator (cooling) coil for each ton of air conditioner capacity.

One ton = 12,000 BTUH so if your AC unit is a 24,000 BTUH unit it is a "two ton" unit and needs to see 700 to 800 CFM of air across the evaporator coil.

Some home inspectors and air conditioning service technicians carry a small airflow meter that can actually measure this number with fair accuracy.

The same tool is nice for comparing air flow and balancing air flow at various building supply ducts and registers.

See COOLING COIL or EVAPORATOR COIL
and

also DIRTY COOLING COIL / EVAPORATOR COIL - how dirt and debris appear, what to do about a dirty evaporator coil.

Evaporator coil cleaning

often requires cutting refrigerant lines, removal of the coil and other components for cleaning, and reinstallation, pulling a vacuum on the refrigerant lines, and recharge with refrigerant. Such service and repair may involve significant expense, although there are some "in place" cleaning methods using foams and sprays that are a simpler procedure.

Compressor / Condenser Unit

Condensate Handling

Controls & Switches

Cooling / Evaporator Coil

Electrical Problems

Heat Pumps & Backup Heat

Operating Conditions, Noised & Defects

Refrigant Gas Charge, Leaks, Repairs

...




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

AC Compressor won't run

I have a outside heat pump unit and the heat works , but when I turn on A/C the compressor doesn’t come on. The plug to compressor was unplugged so I plugged it in and unit sounded like it shorted out. Any thoughts - On 2020-07-25 by Brandon -

Rely by (mod)

That sounds to me as if a relay or control board has shorted out or worse, a short circuit occurred in the compressor motor itself.

Musty odor from the air conditioner

A musty smell when unit comes on - On 2019-10-03 by Anonymous -

Rely by (mod)

Anon: check for mold and water in the air handler supply and return plenums and in the ductwork.

See details at HVAC SYSTEM ODORS 

 

 

HVAC Unit Control board has no power out - bad transformer?

My control board has power going to transformer but no power out. Is it a bad transformer? - On 2019-07-19 by Rick

Reply by (mod) -

It certainly could be a bad Transformer, or something as simple as a loose or broken connector. I would check all the connectors in and out before replacing the parts.

...

Continue reading at COMPRESSOR / CONDENSER DIAGNOSTICS, or see AIR HANDLER / BLOWER UNIT DIAGNOSTICS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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