1. The main gas control valve right through the diaphragm and through the main on-off valve on top of the valve.

2. At the seams where the valve parts meet each other. The gasket leaks.

3. At all of the pilot tubing connections. These are commonly miss-threaded.

4. At any gas shut off (main or pilot) that contains a spring. The spring gets weak.

5. At any flared fitting. This is especially true if someone used pipe dope or Teflon tape on it.

The Repair Never Use Teflon Tape It tends to leak gas. Most Teflon tape is not rated for gas.
The normal repair would be to install a more fuel efficient electronic ignition assembly. We wish to do away with pilot lights because of the waste in fuel year long and safety concerns. They tend to burn the firebox out and if it does develop a gas leak then the pilot would be a close proximity ignition source. If you do elect to replace the gas valve with a like replacement it is mandatory that if the system uses a thermocouple that you change it out. The movement that you cause when you take the thermocouple on and off can break the tiny electrical wires in it and cause a recall. The thermocouples are not valuable enough to not install them. If the valve is hooked up with a gas flex that is too small, is made out of rigid aluminum or brass you must also change it out. If the gas cock serving the furnace has a spring on it then it must also be changed out as it is no longer code approved.

Hint:     Always give your customer the opportunity to replace the furnace or fix the furnace. It should always be their choice if the furnace can be fixed. If your customer opts to fix the furnace you can give them an option for 30 days. We can credit the amount (all or most) to the replacement if they elect to have us perform the replacement. Many people have a hard time making up their mind. This gives them the best of both worlds and you are much more likely to perform the needed work.

The Tif 8800 Combustible gas leak detector is a very good Sales & Diagnostic tool.

Not only does the tool work very well, but it enables the homeowner to hear where the leak is and become involved. The loud shrill noise of the “Geiger like” counter notifies everyone within earshot that something is wrong. This prompts the customer to ask what the noise is all about. Your response should be to explain the tool and show them where the leak is. The majority of gas leaks inside a heating system are from internal failures of the gas valve. The valve must be replaced necessitating a repair for you to perform.

Compressors

This section is about compressors and condensers. The compressor is only one component in the condensing unit. This section has been completely rewritten as a diagnostic flow chart and should be able to help you find the majority of problems in the field. There are 2 main types of compressors that we deal with. The diagnostics procedures are nearly the same with each one of the different types of compressors. The compressors are and have always been little more than a large motor that is hermetically sealed.

1) The Reciprocating. This has been the staple of the heating and air conditioning industry since its inception. The problems associated with this compressor have been solved long ago. It is very reliable. This compressor has a crank, rod, and piston and operates very similar to a car engine.

2) The Scroll. Picture a double spiral. One of the spirals squeezes the Freon up against the inner side of the other one continually pushing the Freon forward compressing it. This type of design has been around a long time, but has only within the past few years been manufactured small enough to be used in residential applications. Copeland came out with the first for residential. They had a tremendous number of problems. Scroll compressors typically start easier than reciprocating but they can not handle any liquid Freon in the case. The scroll compressor should be more reliable as it has fewer moving parts, but so far that reliability gain has not been seen. The following diagnostic procedures are important to follow in the field. These procedures are designed to be thorough. This is to prevent call backs. This procedures must be followed. These will prevent you from JUMPING TO CONCLUSIONS. This is a major problem in this field. If the fuses blow the solution is not to just replace them. It is to find out why they blew in the first place and to prevent them from blowing again. If the fan motor burns up, the solution is rarely to replace the motor. The wiring may be the problem, or perhaps the motor is the wrong size. The fan may be pushing the air in the wrong direction, or perhaps the capacitor is weak or shorted. Finding the source of the problem and correcting it is your job. Do not treat only the symptoms.

Part 1:     Prior to Diagnosing any Problem with the Condenser it is Assumed that You Have Performed the Following.
You cannot diagnose the problems in an air conditioning system without first performing these pre-checks.

1. Ask the person responsible for the A/C what they think the problem is. Remember this is the person that you trying to please. If their version of what is wrong is close to what is actually wrong,  it can go a long ways towards customer satisfaction to agree with them. They will feel good about the decision and the direction of the repair.

2. Have you performed a Visual Inspection of the heating system. Notice the problems and point them out. Are these problems the reason for the current breakdown? See the section on visual inspections for further details.

3. Have the homeowner turn on the A/C. Many times the problem with the A/C is that the homeowners do not turn on the A/C properly. They do not know how to operate the thermostat.

4. Turn the thermostat down to the coldest level. This is so that the thermostat does not turn the system off when you are working on it. At this stage you are trying to find out what is wrong. You are not trying to calibrate the thermostat.

5. Made sure that the air handler is running. I can’t tell you how many times I have had a service technician miss-diagnose a system simply because they never knew the air handler wasn’t running.