Air Conditioner Inspection Checklist:

This air conditioning inspection article discusses the how to perform a simple visual inspection of an air conditioning compressor-condenser unit, including links to more detailed air conditioning inspection,diagnosis and repair articles useful in the evaluation of air conditioner compressor noises, hard starting, lost cooling capacity, and detection of a burned out compressor or A/C compressors at or near end of their life.

Maintenance tips including attention to compressor support pads and avoiding air conditioning refrigerant leaks are addressed.

How do We Inspect an Air Conditioning or Heat Pump Compressor / Condenser Unit:

This Simple Visual Inspection Procedure Can Disclose Damage or Operating Problems

Here we provide sketches and photographs and descriptions of common defects for each A/C component along with visual or other clues that may suggest a problem or probable failure of each component.

We explain how an air conditioning service technician will diagnose certain common air conditioning system failures or defects. We include photographs to assist readers in recognizing cooling system defects.

The (usually) outdoor half of a typical air conditioning system is a unit containing the refrigerant compressor and condensing coil.

The air conditioning compressor motor is a pump which draws heat laden refrigerant gas from the building's indoor components (evaporator coil and air handler), and compresses the low pressure refrigerant gas to high pressure and higher temperature.

The diagnosis and repair of various defects in the air conditioning compressor/condenser unit are discussed in detail using the links provided at the end of this article .

Here is a little visual inspection checklist that any homeowner or home inspector can perform.

Sketch courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [carsondunlop.com].

AIR CONDITIONING & HEAT PUMP SYSTEMS describes the major components of an air conditioning system.

 

If your air conditioning or heat pump system has lost its cooling capacity or won't start
see REPAIR GUIDE for AIR CONDITIONERS.

If the system seems to be working but is inadequate to cool your buildinge see COOLING CAPACITY, RATED of air conditioning equipment.

 

Air Conditioner Compressor Unit Inspection Checklist - Outdoor Unit Observations

• Location of the Compressor/Condenser:
  
  Locate the outdoor unit or units and look at the characteristics of just where the unit(s) have been placed:
  • Is there good air circulation 
    
    around the compressor/condenser unit or is it too close to a wall, to close to an overhead deck, porch, shrubs - Details are
    
    at COMPRESSOR / CONDENSER INSTALLATION ERRORS
  • Is the unit too close to the property line 
    
    a possible noise issue for neighbors or a local building code violation? Most municipalities require that the compressor be at least 10' from the property line.
  • Is the compressor/condenser too close to a gas appliance vent or to a clothes dryer vent? -
    
    Details are
    
    at COMPRESSOR / CONDENSER INSTALLATION ERRORS
  • Are all of the cabinet parts and cabinet base above ground -
    
    the unit should not be partially buried
• Cabinet condition for compressor/condenser:
  
  look for rust damage or dents from having been struck by a garden tractor or dropped during installation
• Condensing Coil blockage, damage, dirt: 
  
  look for evidence of damage to the cooling fins or dirt, debris, grass clippings blocking the air flow of the unit.
  
  See CONDENSING COIL REPAIR REPLACE
• Compressor/condenser fan damaged, loose, bent:
  
  look for evidence of damage to the fan itself (rare).
  
  See FAN, COMPRESSOR / CONDENSER UNIT for details.
• Compressor motor damage or overheating
  
  may be indicated by smells, odors, noises (humming, hard-starting) or by oil leaks.
  
  Initial, simple diagnostic checks of the air conditioning compressor are described
  
  at COMPRESSOR / CONDENSER REPAIR
  
  See TIGHT or SEIZED AC COMPRESSORS
  Also
  
  see AIR CONDITIONING & HEAT PUMP NOISES
• Data Plate Information
  
   for the A/C or heat pump system: is there a data plate at all? If you can find it, record the model, serial number, and other data from this tag - it can help locate service manuals, system specifications such as RLA, maximum fuse size, and it will permit you to find the age and cooling capacity of the unit.
  
  See DATA TAGS on AIR CONDITIONERS. A home inspector can be asked to make a rough comparison between the cooling capacity of the compressor and the square footage of the building it serves.
  
  See COOLING CAPACITY, RATED for how to do this,
  and
  
  see AIR CONDITIONER BTU CHART.
• Electrical service disconnect switch
  
  at the air conditioner compressor/condenser: a service disconnect switch, fuse, or circuit breaker should be installed, usually on the building wall close to the unit.
  
  Check the size of the fuse or circuit breakers and compare with the overcurrent protection specified on the data plate on the compressor/condenser unit body.
  
  See A/C - HEAT PUMP CONTROLS & SWITCHES.
• Fan not working, noisy, rattling 
  
  on the outdoor compressor/condenser
  
  See FAN, COMPRESSOR / CONDENSER UNIT - if the fan on the outdoor compressor / condenser unit is not working properly
• Levelness of the condenser/compressor
  
   unit: the unit should be level or within 10 deg. of level.
  
  See CONDENSING COIL REPAIR REPLACE
• Noises at the air conditioner: 
  
  if the compressor can be run, listen to the motor and fan motor when the unit starts and after it gets running; Noisy or hard starting compressors may be at or near the end of life or may need service and repair.
  
  See NOISES, COMPRESSOR CONDENSER,
  and
  see OPERATING DEFECTS.
• Refrigerant charge problems:
  
  while you cannot see the refrigerant level directly in residential and light commercial air conditioners or heat pumps, some systems provider a sight glass that can give a clue indicating low refrigerant charge: bubbles visible in a sight glass located in the compressor/condenser unit near the receiver.
  
  See REFRIGERANT SIGHT GLASS. Bubbling or gurgling sounds in the refrigerant lines can also offer a similar clue.
• Refreigerant piping leaks, insulation; condition of the air conditioner refrigerant lines:
  
  look for lost insulation on the suction line; look for absence of any bend or slack in the refrigerant line; if the compressor/condenser is connected to copper piping that is rigid between the unit and the building wall, vibration, settlement, slight movement can produce a refrigerant leak.
  
  See REFRIGERANT GASES & PIPING
  and
  see REFRIGERANT LEAK DETECTION.
• Temperatures of operation: 
  
  a home inspector or service technician may use other instruments, including measuring simple air temperatures at the compressor/condenser to get an idea how well the system is functioning.
  
  See AIR CONDITIONER TEMPERATURES (also useful for heat pump systems)
  and
  See AIR CONDITIONER TEMPERATURE MEASUREMENT for measurement points & procedures
• Wiring for the air conditioner or heat pump:
  
   inspect the wiring, fusing, overcurrent protection, circuit breakers supplying electrical power to the air conditioner compressor/condenser unit: look for signs of damage or overheating, broken conduit that should be protecting the wiring.
  
  A home inspector or electrical inspector will compare the size (current carrying capacity) of the wiring with the fuse or circuit breaker size and the size specified by the data tag. She should also check that the wiring to the compressor/condenser is rated for outdoor use or is suitably installed in conduit.
  
  See ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR.

Key Air Conditioning or Heat Pump System Diagnostic Articles

• at LOST COOLING CAPACITY, our focus is on the case in which the air conditioning system seems to be "running" but not enough cool air, or no cool air at all is being delivered to the occupied space. Sketch from Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].
• at OPERATING DEFECTS we take you through the major air conditioning problem symptoms and how to get the air conditioning system working again.
• at A/C - HEAT PUMP CONTROLS & SWITCHES we explain the many electrical switches and controls that control an air conditioner or heat pump system. You'll need to check these if your air conditioner won't start
  .
• DIAGNOSTIC GUIDE A/C or HEAT PUMP
• DIAGNOSTIC DETAILS A/C or HEAT PUMP

...

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: what's inside of a hermetically-sealed compressor unit?

What is inside if the air compressor units if you cut them open (May 10, 2011) Anonymous

Reply: refrigerant gas and a bit of oil.

COMPRESSOR / CONDENSER REPAIR shows what is inside of that sealed A/C compressor motor. There we include illustrations and text.

 

Question: effects of trees & shade on compressor / condenser units

A question which just came up: A large tree was recently cut back which had provided shade for my outdoor condenser which faces southwest.

Will the efficiency of the unit be adversely affected by this exposure to the hot uninterrupted summer sun? Your comments will be of great help for someone who obviously is not very knowledgeable. Thanks. (June 12, 2011) estelle j.

Reply:

Shade and A/C condenser units: good question Estelle. The outdoor condenser indeed has a slightly easier time of it if located in shade, though the units are designed to be capable of functioning in full sunlight. I have not found a source that gives us actual data on the change of system efficiency when shaded. So I'm reluctant to give a "made-up" number guess.

You can do several things to restore shade to your compressor unit such as:

- temporarily install a beach umbrella to shade the unit

- build a pergola or lattice-work cover above the unit

WATCH OUT - don't put any shade over the compressor/condenser that is so close to the unit's air inlet or outlet or that is so closed as to block airflow over the unit.

Most A/C compressor installation manuals will give the required clearances around all sides and above the unit in order that its airflow is not obstructed. If you can't find that information, and if your shade source is at least six feet above the unit you should be OK.

(Apr 26, 2012) kristopheruu said: that was very helpful

 

Question: I turned our A/C unit on and it is blowing hot air

I turned our A/C unit on and it is blowing hot air. I checked the outside unit and the fan is on.

I was standing by it when it came on, the fan came on first, then a few seconds later I heard the compressor come on, it was humming pretty loud.

The pressure line going into the unit was very warm. I checked the coils inside the house, (air handler?) and they were pretty warm also. Could this be the start up capacitor? Thanks. (Mar 16, 2012) Jeff

Reply:

See the diagnostic procedures beginning at LOST COOLING CAPACITY

 

Question: cutoff valves on AC / heat pump refrigerant lines?

My condensing unit is Carrier but the hot gas bypass has a cutoff valve, Can I install a new compressor whithout unloding the system's capability - that is, can it keep running? (May 15, 2012) slam jeme

Reply:

Slam Jeme I haven't seen cutoff valves on refrigeration lines, but if that's what youv'e got it may be that a swap-out ability was what was intended. Just ask your tech how they are going to get all of the air out of the new system and lines during the reconnection process.

Watch out: a shutoff valve on a refrigerant line can prevent proper compressor/condenser operation and may be unsafe to boot.

 

Question: outdoor compressor fan not running

The outdoor compressor fan is not turning even though the a/c is running. Air does not seem as strong or as cool as it usually is. Should I turn it off in order not to burn up the motor, or what are my other options? Can it be fixed?

The fan on the outdoor condenser is turning, but at a slower speed. The air coming from the top of it is cool, not warm. It makes a sound like a stick being run across a grate periodically as if it's trying to kick into a higher gear. (June 19, 2012) Evilu Pridgeon

The sound lasts about 3-4 seconds. Indoor runs but air is somewhat cool. Capacitor was tested and checks out fine (it was installed last summer). We currently have it turned off. Any suggestions? (Sept 18, 2012) Cathy C.

Reply:

Evilu if the outdoor fan is not turning but the outdoor compressor motor is trying to run it sounds like a fan relay or fan start run capacitor problem.

Watch out: TURN OFF the system to avoid damaging it while you wait for repair.

Cathy:

See FAN, COMPRESSOR / CONDENSER UNIT - if the fan on the outdoor compressor / condenser unit is not working properly

 

Question: condenser stoppd working, jiggled wires and it starts

My condenser stopped working a few months ago there was no noise of it trying to start just nothing at all. The other day I was looking at it and decided to jiggle the wires coming from the blower and the unit started right up and shut down. I jiggles the again and it started right back up.

I could see the wire nuts holding the wires together and decided to reconnect them better.

When doing so they came out of the wire nuts. I had a blue and yellow wire coming from the condenser.

And a red and white wire coming from the blower. No matter what combination I tried I could not get the unit to work again. And now nothing is working blower, heater, or the condenser. Any suggestions? I have tried all breaker that I know of. (Jan 26, 2013) Dooley

Reply:

Sounds as if in moving wires around you may have blown a fuse or mis-wired the unit. Ask for help from your heating service tech.

Watch out: Meanwhile leave power to the unit turned off for safety.

 

Question: split system AC display unit blinks on and off

After switching on split AC, and starting through Display unit, Display shows for 7 to 8 seconds and off for 4 to 5 seconds. A C unit dosen't work.

Can any expert tell why this happening? or cause of this? (June 29, 2014) Bapurao

Reply:

Bapuaro

If a display is cycling on and off I'd look for a condition that is causing the system to lose power itself or a loose switch, or an overload causing a system reset.

 

Question: minimum outdoor temperature for an accurate AC tuneup or freon check

What is the minimum outdoor temperature for accurate tune up/maintenance/ Freon level check? 28 Feb 2015 Phylon said:

Reply:

Pylon

In the inspection points for A/C and heat pumps listed in the article above please see "Temperatures of Operation" where you'll find a link to a detailed article diving operating temperatures and the measurement procedures.

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Continue reading at A/C - HEAT PUMP CRITICAL DEFECTS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• DEFECTS LIST - AIR CONDITIONING
• A/C INSPECTION LIMITATIONS

Suggested citation for this web page

A/C INSPECTION CHECKLIST - OUTDOOR UNIT at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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