If Refrigerator Freezes Food, Check for Leak

QUESTION: I have an old Frigidaire combination refrigerator-freezer with the freezer on top and the thermostat in the evaporator. With the thermostat set at “A,� the freezer is cold enough but the refrigerator is at about 28 degrees Fahrenheit and the food freezes. With the thermostat at “C� the freezer is about 20 degrees and the refrigerator at about 34 degrees.

When a serviceman looked at the refrigerator he said there were drops of oil in the compressor terminals. This indicated a refrigerant leak, which he said would cost $300 to fix. I realize that this appliance has reached a ripe old age. However, it’s still capable of freezing food and is only used intermittently for extra cold storage space at holiday time.

ANSWER: A drop of oil on the compressor terminals might or might not indicate a refrigerant leak. A good way to see if you have a leak is to look at your freezer coil. Begin by defrosting the refrigerator thoroughly. Turn the thermostat back on and let the refrigerator run for a while, then open the door. Check the frost pattern on the freezer coil. There should be frost all over the coil. This would indicate there is no refrigerant leak.

If only a small portion of the coil is frosted, this could indicate a slight shortage of refrigerant in the system. You can have a serviceman add refrigerant to the system. This would not be too expensive and it would keep your refrigerator going, especially if it is not in day-to-day service.

If you do have a good frost pattern on the coil in the freezer, we would suspect a defective thermostat if everything is getting too cold in the refrigerator section when the freezer is operating at the correct temperature. Replacing it is a straightforward job. Just make sure you get the correct part for your model.

Can Copper Water Pipe Be Fixed With Plastic?

Q: I’m replacing some bad sections of copper water pipe. Can I use PVC pipe for the repairs?

A: Plastic water pipe can be jointed to steel and copper pipe by means of plastic threaded adapters. Both male and female plastic adapters are available. One end of the plastic adapter is glued to the plastic pipe and the other threaded into a fitting or onto a pipe. When joining plastic water pipe to existing metal piping, wrap the male threads with plastic pipe joint sealant tape. Because plastic female adapters can expand when threaded onto male threads, a better choice is to use a plastic male adapter threaded into an iron or copper female adapter or fitting.

Vent Pipe Needed to Dissipate Sewer Gas

Q: Can you explain the working and purpose of a vent pipe? Some months ago, during a heavy rain, water came pouring into a third-floor room. Our roofer came and said it was not a roof defect, that there might be a break or blockage inside the vent pipe. He filled a plastic beverage bottle with water and inserted it in the top of the vent. We have had no flooding since. However, at times I sense an unfamiliar odor through the house. My daughter thinks there may be some harmful gases seeping through the house.

A: The odor you smell is probably from sewer gas, which is the result of the vent stack being blocked. The vent pipe must never be obstructed. Its purpose is to vent sewer gas to the atmosphere and to maintain atmospheric pressure within the drainage system.

Each plumbing fixture, such as a sink, has a bend known as a P trap, as part of its drainage piping. A little water is left in the trap every time water drains from the fixture. The trapped water forms a seal to block sewer gas (which is normally present in the drain line) from entering the house.

When it rains, water enters the opening at the top of the vent stack. Normally this is not a problem. However, if the vent pipe is offset in the attic, and if this offset section is cracked or has a hole, water will drip onto the floor and wet the ceiling below.

If the vent stack is blocked, the sewer gas will rise to the point of the obstruction and then back out to a point where it can escape, such as a crack or hole. It can build up enough pressure to force its way past the water in the trap. In your case, the sewer gas is probably seeping out a crack in the vent stack, and from there the gas makes its way into the attic and seeps into the rest of the house.

We suggest you look in the attic for the source of the leak. Don’t forget to remove the plastic beverage bottle from the vent stack.

For further information on any home problem, write to Popular Mechanics, Readers Service Bureau, 224 W. 57th St., New York, N.Y. 10019.