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Posted 07/27/2019 in HVAC

Air Conditioning Repair | 4 Helpful DIY Tips Before Calling a Technician

Air Conditioning Repair | 4 Helpful DIY Tips Before Calling a Technician

Help! It's 90+ degrees outside, you are hosting a dinner party in a few hours...and your air conditioner (A/C) just quit! Therefore, the last thing you need, or want to be worrying about is air conditioning repair...am I right?

Sound familiar?

It seems like this exact scenario happens all the time, and it has happened to me! Due to the fact that your air conditioner will always fail at the worst possible time, or on the hottest day of the year [Murphy's Law], we're going to give you a few simple DIY tips that will get you back up and running, and in no time at all!

The Dog Days of Summer got ya down? Stay tuned because this info may just prevent a delayed and EXPENSIVE service call from your friendly Heating, Ventilation, and A/C (HVAC) professional! Lets get started!


  1. Air Conditioning Basics Operation
  2. Air Conditioning Repair Basics - The Scope
  3. Air Conditioning Repair - Prep and Setup
  4. 4 Helpful Tips Before Calling a Technician
  5. Help! My A/C Still doesn't Work
  6. Additional Resources


Air Conditioning Basics - The Operation

First of all, your air conditioner only needs a few MAIN ingredients for normal cooling and operation. Those three main "ingredients" are listed below, and the rest is taken care of by all the other major A/C mechanical and electrical components that comprise your system. Most air conditioning failures and repairs involve the following issues:

  • Thermostat Failure - the main control and user interface
  • Electricity/Power Failure - main power provided and controlled from the breaker panel, wet switch, and lockout switch (outside)
  • Refrigerant Leaks  - the internal coolant commonly referred to as  "Freon"


Air Conditioning Repair Basics - The Scope

Furthermore, it's a given that the average Homeowner does not have the ability to repair major A/C system items or components due to specialized HVAC equipment and tools that are usually needed. So, the focus and Scope of this article will be on DIY Homeowner repairs and tips. Additionally, these tips can be easily accomplished with basic, general tools and knowledge.  

Any additional repairs outside of this scope may need to be performed by an HVAC professional or technician.


Air Conditioning Repair - Prep and Setup

Before you can asses, inspect, or fix anything, you need to locate, identify, and become familiar with some major items and A/C system components. The following A/C items should be located outside or in your attic, basement, service closet, or garage.

NOTE - Electrical Hazard: When working on ANY electrical equipment, ALWAYS make sure the main power source is unplugged / switched OFF / locked out BEFORE service or repair is attempted.

So let's get started on A/C component identification!


Air Conditioner Thermostat

  • Usually located on main floor level of homes. 
  • Sometimes located on multiple levels of the home.
  • Serves as the main control panel for the A/C unit - on/off, fan, heat, A/C.

home hvac thermostat on wallHouse Thermostat 


Main Electrical Service Panel

  • Usually in the basement, service closet, garage.
  • The main "power control center" for all your home's electrical circuit breakers.
  • Supplies the main power to the HVAC or A/C unit.

house electrical panel, 200 ampHouse Electrical Panel, 200A


Air Conditioner Condenser

  • Usually located outside and close to the house.
  • Sometimes located on a roof.
  • Transfers heat; cools down and condenses refrigerant vapor into liquid.

a heat pump air conditioner condenserAir Conditioner Condenser


Air Conditioner Condenser Service Lockout Switch

  • Usually located outside and near the A/C Condenser.
  • Locks out the power between the main breaker panel and the A/C Condenser.
  • Enables safe maintenance and repair for the homeowner or technician.

an air conditioner condenser and lockout switch, outsideExterior Condenser and Lockout Switch


A/C Air Handler (with drip pan)

  • Usually located in the attic, and/or basement, service closet, garage.
  • A split-system may be located in an attic AND basement.
  • Usually located with the air filter box (unless you have a cold air return filter box).
  • The unit filters, delivers, and returns the conditioned air - continually throughout the house and back to the unit.

a unico system air handler unit in house atticUnico System Handler in Attic 


A/C Air Handler Wet Switch

  • Safety item - It protects against flooding from a clogged or overflowing drain pan.
  • Usually located in the bottom of air handler drain pan. Looks like a hockey puck with a red/green light.
  • Should be located to the SIDE of the drain pan - out of the path of normal condensation draining and drips. 
  • Location is important! Otherwise, you may get a false system shutdown, and you  DON'T want that!!! The Wet Switch has a Test and Reset button.

hvac air handler wet switchHVAC Air Handler "Wet Switch"


Air Conditioning Repair - 4 Helpful DIY Tips Before Calling a Technician

Ok, now that you are familiar with the major A/C System items and components, and where they are located...let's run down a short list of things to check BEFORE you call you call a technician for air conditioning repair.

 These are super easy, so let's get to it!


1.  Check the Air Conditioner Thermostat

a nest smart thermostatNEST Thermostat 

Symptoms/Possible Fix

  • No air blowing from your vents at all  >>>  is the system turned on? Do you have power to the thermostat?
  • Only warm/ambient air is blowing from the vents  >>>  make sure the system is on COOL and not the FAN, or HEAT setting.
  • If everything looks OK, check the power supply (electricity) next  >>>  see #2 below.  

2.  Check the Main Breaker Panel

  • First, locate and open the main Main Breaker Panel.

a house electrical panel, 200 amp

House Electrical Panel, 200A

Symptoms/Possible Fix

  • Next, locate the breakers for the A/C AIR HANDLER and A/C CONDENSER UNIT  (likely "double" breakers as shown here, and 20-30A) - SEE RED [X] below.

home electrical panel and circuit breakersService Panel and Circuit Breakers

  • Flip each breaker (off) toward the BREAKER LABEL,  and back  (on) toward the CENTER of the panel. This will ensure the breaker hasn't "tripped" or malfunctioned. As a result, the breaker should stay engaged and locked toward the CENTER after you reset it.
  • Finally, if everything looks OK at the panel, check the power to the A/C Condenser, next. See step #3.


3.  Check the A/C Condenser Service Lockout Switch

  • First, locate the A/C Condenser Lockout Switch. The one shown below is outside next to the air conditioner/HVAC condenser.

heat pump ac lockout switchExterior HVAC Lockout Switch

Symptoms/Possible Fix

  • Open the A/C Condenser Service Lockout Switch cover.

 hvac ac condenser service lockout switchHVAC Lockout Switch Panel

  • IMPORTANT - Read the instructions, make sure the switch is NOT loose, AND make sure that the removable switch is pushed all the way in/firmly secure. Also make sure that it is not accidentally "locked out" (when you remove it, invert it upside down, and reinstall) -  this cuts the power to the condenser (outside) WITHOUT having to access the main breaker panel in the house, basement, etc.

hvac service lockout panel instructionsLockout Panel Instructions


4.  Check the Air Handler Wet Switch


Symptoms/Possible Fix

  • If it comes in to contact and detects ANY water absorbed by the felt base, it WILL completely cut the power and shut down the HVAC system. First, locate the Air Handler Wet Switch (in the air handler bottom drain pan).air handler wet switch
    HVAC Wet Switch

  • RED light = the bottom "felt" pad is WET from being in the path of normal condensation/water OR the air handler drain pan is flooded from a clogged drain.

tripped air handler wet switchHVAC Wet Switch - Tripped

  • Clear the drain pan drain if needed.
  • Dry the "felt" pad on the bottom of the Wet Switch with a hair dryer - takes about 2 minutes

drying the hvac wet switchDry the Wet Switch Base

  • GREEN light = Once the "felt" pad is thoroughly dried on the base of the switch, push the RESET button. A GREEN light is good!

 resetting a hvac wet switchReset the Wet Switch

  • Re-position the Wet Switch out near the edge, inside the air handler drain pan.
  • DONE - turn the thermostat back on and give the system about 10 minutes to complete the HOLD / RESTART sequence.
  • Finally, if the outside A/C Condenser fan is running, you should have COLD air!

exterior air conditioner condenserAir Conditioner Condenser


Air Conditioning Repair - Help, My Air Conditioner Still Doesn't Work

Above all, if you have tried the 4 DIY tips mentioned above and your A/C is still not working properly, it may be time to call an HVAC professional or technician. You may be experiencing more difficult A/C system issues like:

  • Refrigerant (Freon) leak.
  • Mechanical component problem or failure inside the A/C Condenser OR Air Handler Unit.
  • Electrical component problem or failure inside the A/C Condenser OR Air Handler Unit.


hvac repair toolsHVAC Repair Tools


NOTE - Electrical Hazard: When working on ANY electrical equipment, ALWAYS make sure the main power source is unplugged / switched OFF / locked out BEFORE service or repair is attempted.


Air Conditioning Repair - Additional Resources

What is a Wet Switch?

Main Breaker Panel Info

For More Old House Air Conditioning Info

More AC Repair and Troubleshooting Chart

Best of luck, and keep on Fixing!   

Christopher Hewett My Old House Fix

For more info visit:  www.myoldhousefix.com

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