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Troubleshooting Heating and Cooling

Troubleshooting a furnace or air conditioner whether it be fired by gas, electricity or oil requires special tools, testing equipment and a host of other items. Glossary of Heating and Air Conditioning Parts Since most people who are mechanically inclined may have some of this equipment there is the danger that they will think they can handle the job. To these people let us say up front, the author of this article is a Certified General Motors mechanic, but just as the automotive industry has added such things as air bags, computers, fuel injection, turbo chargers, superchargers and many other new components, so have the H.V.A.C. manufacturers. While you may have some of the equipment to test a vehicle, chances are you will only get just so far in troubleshooting the newer components. Then there is the chance of getting hurt as in the case of working on an air bag system not to mention damaging expensive parts from the lack of having the right testing equipment. New furnaces and air conditioners have the same issues. As an example, the newest type of refrigerant out in some air conditioners use R-410A refrigerant which has the possibility of running operating pressures into the 700 pound range. A brand new set of refrigerant gauges and hoses which are meant for the old refrigerants are only rated for about 650 pounds! All H.V.A.C. technicians have to buy new gauges and matching hoses not to mention new refrigerant recovery equipment as required by the E.P.A. If they don't, someone is going to get hurt for sure! We are writing this article only as a guide and strongly suggest that you call a reputable H.V.A.C. service professional to service your gas, electric or oil furnace and your gas, or electric heat pump or air conditioner.

So with all that said we will attempt to write this page with the emphasis on simple troubleshooting aimed at the average homeowner. If you are more mechanically inclined than this please bear with us as we will include more technical advise noted as " For Advanced Troubleshooting ".

FURNACES:

DESCRIPTION: Oil, natural gas, L.P.gas fired and electric strip heat.

Most older gas furnaces usually have a pilot which burns all the time. This pilot burns and its flame must touch a sensing device called a thermocouple. The thermocouple generates a small amount of electricity within itself. Standing Pilot ThermocouplesNote: " For Advanced Troubleshooting " There are millivolt systems which use pilot generators thermopilegenerator that are totally different than the thermocouples used in standard 24 volt furnaces. The thermocouple can fail thus providing a safety against the furnace trying to send raw gas to the burners with no pilot present. If your pilot won't stay lit even though you have followed the pilot lighting instructions usually posted within the furnace burner compartment continue reading here. These instructions vary from furnace to furnace but usually amount to turning the gas valve knob to the pilot position, holding down on the gas valve knob ( sometimes a separate knob ) while lighting the pilot with a long match and then continuing holding down for (2) minutes. After this 2 minute hold down period release the knob. The pilot should remain lit. If it stays lit, turn the knob to the " ON " position. The burners should light if the power is on and the thermostat is calling for heat. If the pilot goes out immediately after you have held the knob down for (2) minutes you probably have a bad thermocouple. This is the number one call we get on these old furnaces. There are also various electronic pilots used, especially in older furnaces such as the following, Bryant LH33WZ512A Spark Igniter, Carrier Pilot Burner. Be aware however, a bad gas valve Robertshaw 700 Gas Valvesor open high temperature limit control Fan Limit Controls can sometimes cause similar reactions.

In oil furnaces this thermocouple is for the purposes of this article, replaced with a cad cell or flame eye which serves the same purpose as a thermocouple. If the oil and air mixture isn't ignited within 15 seconds the oil pump will shut down on safety. When this happens a reset button will pop up on the burner control box and must be reset.
Oil Burners\R8184M Primary Control" For Advanced Troubleshooting " Resetting this button multiple times will flood the fire box with raw oil and if ignition does take place there can be a serious fire or explosion!! There is no pilot on oil furnaces and no attempt to reach in the fire box with a lit match should EVER be made! Ignition in oil furnaces takes place by use of a high powered transformer and ignition electrodes." For Advanced Troubleshooting " These electrodes have a certain gap and angle that need to be set for proper ignition similar to spark plugs in a vehicle. Also oil furnaces have a pump which must develop 100 P.S.I. of pressure and an adjustable air venturi that must be adjusted to spray an atomized mist of oil and air at the right timing for correct ignition to take place AND within 15 seconds. As you can see there are many reasons to have an oil furnace cleaned and adjusted by a trained service professional before the heating season. Be sure there is a new oil filter in the oil supply line before the heating season and that you are using new oil that is not contaminated with water. An oil nozzle of the right size and spray pattern for the particular furnace should be changed along with the oil strainer on a routine tune up. We have seen many oil furnaces that were installed by homeowners or incompetent installers with NO oil filter in the supply line! Any air leaks in the oil lines will cause a loss of prime to the pump and result in no ignition within the 15 seconds required. We have seen many old oil systems with lines buried outside that, over time, develop leaks - Good Luck finding them. Every effort should be made to check the other possible problems out first before tearing up your lines. A good oil furnace service technician can locate leaks using a pressure gauge. One biggest suggestion from us is KEEP YOUR SYSTEM CLEAN. How well will your car run with gasoline that is 9 months old and full of water from sitting idle?

Furnaces over 1985 vintage:

If your gas has a small motor which you hear running ( not the main blower motor ) you most likely have a system that is loosely called an induced draft furnace. Inducers That small motor is supposed to be " inducing a draft through the furnace heat exchanger ". Usually this is the sequence of operation for these furnaces.

On a call for heat from the thermostat Thermostats the first thing that happens is that small inducer motor runs. After a couple of minutes either a spark ignition Fenwal Direct Spark Ign L37-930 Controltakes place at an electronic pilotor a Hot Surface Ignitor Gas Furnace Parts begins to glow " Red ".

Once a burning pilot takes place or the ignitor glows red Gas Furnace Parts, a signal is then sent often times to a Printed Circuit Board Circuit Boards( Microprocessor ) or ( mini computer ). Then and only then, will the burners try to light. These printed circuit boards provide an extremely safe furnace in that if the furnace doesn't light in ( 3 ) tries it will go into lock out mode. To remove it from lock out turn the main power off to the furnace and right back on. This will reset it and it will try 3 more times to light. " For Advanced Troubleshooting " Spark ignition systems also have a gap that needs to be set correctly. Hot Surface Ignitors have a certain resistance value for each ignitor manufacturer. Printed circuit boards are very un forgiving as to improper grounding and polarity of the line voltage wiring to the furnace and can be damaged by power surges, lightning and improper testing! Some of these boards can cost a couple of hundred dollars depending on the brand and model of furnace so be VERY careful! We DO NOT suggest you get into this for safety and damage to the equipment reasons.

On any of these furnaces there are so many different parts and testing equipment necessary we require our own technicians to go to factory training classes on an on going basis.

AIR CONDITIONERS:

DESCRIPTION: 230 Volt central systems only.

Yearly preventative maintenance should include checking refrigerant, (freon) Freon Leak Kit electrical controls, Dual Capacitors, Cartridge Fuses, Contactor wiring, air filter Electrostatic Air Filters in the furnace or air handler, belts if so equipped, oiling motors if needed, checking indoor and out door coils for good air flow ( cleanliness ) and operating amperage and refrigerant pressures. To answer the number one question we get from homeowners - no you can't pour freon into the system as you do oil into a vehicle and there is no dipstick as in a vehicle! The refrigerant is put into the system using special gauges, under high pressure used for the purpose, and outdoor temperature, ( has to be at least 65 degrees out side ) indoor conditions and specific " Charging " charts have to be used by qualified personnel to properly charge your system. Many times we are asked by people such as Apartment Maintenance people " What should the operating pressures be? " This can't be answered this simply as the outdoor temperature, humidity indoors and outdoors, ductwork, blower speed and a whole lot of other things must be considered. There are different refrigerants used and all require the use of gloves, safety glasses and other safety measures. Freon R22 boils at around -40 degrees. That's right it is boiling NOT freezing as most people think. If it comes into contact with your skin or even worse, your eyes - consider that part of your body badly burnt if not gone! Additionally there are serious penalties for venting refrigerants to the atmosphere imposed by the E.P.A. A Federal License is required to handle these refrigerants. " For Advanced Troubleshooting " Mixing of different refrigerants will result in damage to equipment as well as possible serious physical dangers!

HEAT PUMPS:

Heat Pump
Online resource to buy Heat Pump, Goodman Heat Pump, Goodman Air Conditioner, at lower prices.

DESCRIPTION: Air source.

Service should be done at the beginning of the heating season and before the cooling season. The maintenance is much the same as for central air conditioners with many added controls to be "checked". Again, the single most important thing for a home owner to check is the furnace air filter. Filters need to be changed at least every 60 days during the heating and cooling season. Furnace heat exchangers, evaporator coils, motors and the compressor of your air conditioner all depend on a clean filter. Not to mention your utility bill will skyrocket with a dirty filter!

Heat pumps are basic air conditioners which have the capability of reversing the flow of refrigerant, thus they begin extracting heat from the air out doors to heat your home with. This reversing cycle takes place through your heat pump thermostat and a reversing valve within the heat pump. As the out door temperature gets colder the heat pump has less to work with and will begin kicking on the auxiliary heat strips or fossil fuel furnace to keep the indoor temperature at the desired point. About every 30 minutes during the winter, the reversing valve has to shift to the cooling mode to melt the ice that naturally builds up on the out door coil. This is known as the defrost cycle and takes place usually through another defrost Printed Circuit Board A Rheem Defrost Control within the out door unit. The old heat pumps had to accomplish this through the use of pressure switches and relays. If the out door unit is not fully charged with " Freon " the only way your home will be heated is with your electric strip heaters or fossil fuel furnace which are very expensive to operate. If you have a high electric bill in the winter look at the heat pump as the prime suspect! The heat strips Electric Furnace Re String Kitsshould only be coming on during the defrost cycle or unusually cold out door temperatures. Don't put the selector on your thermostat on " Emergency Heat " unless the heat pump has a problem. If you do, expect a high electric bill! If you see the Emergency Heat light on all the time you have a problem, call a service professional.

To answer common questions we often get - it is normal to see some ice on the outdoor unit. But it should go away when the reversing valve switches to defrost mode Heat Pump Parts at which time you will hear a " swishing " noise on the out door unit. Then you will see steam rising as the unit melts the ice. This is normal and doesn't require calling the fire department as it is not on fire.

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