Is there one service call more common than another? How about emergencies? Do service calls become routine, or does the thought of some very challenging problem keep your techs on their toes and alert you to customers’ needs?

The News asked our contractor consultants about some of the usual and unusual things their techs encounter when they visit homes and businesses. Let us know about some unusual things your field techs have encountered!

Common problems

Jeff Stewart said that common problems on routine service calls depend on the time of the year.

“Summer versus winter is definitely different,” he said. “For our climate [Las Vegas, NV], summer extremes (115°F) versus regular summer days (100°) can make a significant difference in the problems found.

“But to generalize it, we find that probably 85% of the problems we find are maintenance-related. If I had to put them in order, it would be:

  • “Burnt or loose connections (wires, contactors, controls, fuses);
  • “Freon problems (undercharge, overcharge);
  • “Bad motor bearings (very prevalent in Southwest);
  • “Airflow problems (filters, ducts, coils, etc.); and
  • “Component failure (relays, compressors, solenoids, thermostats, electronic boards, etc.).”

David Dombrowski said, “On routine maintenance we typically find clogged filters, dirty coils, airflow and air leaks with disconnected duct, thermostat calibration, and cracked heat exchangers.

“In addition, many accessories are dead when we first do the preventive maintenance.”

Steve Miles explained, “Dirty filters and an overall lack of maintenance are by far the most common problems we find on our ‘demand service’-type calls.

“These usually lead to the more expensive problems such as blocked evaporator coils, cracked heat exchangers, and bad compressors.”

Bob Dobrowski said, “I think for residential cooling problems, it’s probably blown fuses at the disconnect. Usually a five-minute time delay or hard-start kit prevents further problems.

“For no-heat calls on newer furnaces it is the circuit board. On older furnaces, you replace the board rather than repair because of bad exchangers or a costly repair.

“On commercial problems, I think we see more zone problems than equipment failures. Hot or cold areas many times are the result of a poorly designed system. These problem buildings are good for creating other [service] opportunities.”

Jo Navaretta said that “One of the most common problems my technicians encounter is a pitted contactor. Because the unit still runs, they inform the customer of what they found and what can occur if the part is not changed. They recommend replacement and leave the decision to the customer.”

Tom DiPietro decided to poll his service techs to find out what some of the common service problems are that they encounter. Here are some of the results based on individual answers from his techs:

  • Clogged filters;
  • No room to work;
  • Cracked heat exchangers;
  • Loose connections;
  • Dirty nozzle;
  • Unadjusted electrodes;
  • General lack of recent service;
  • Dirty flame sensor;
  • Bad transformer;
  • Bad oil burner coupling;
  • Chimney plugged;
  • Dirty blower motor;
  • Pilot light outage;
  • Dirty condenser; and
  • Improper gas pressure.

Uncommon problems

David Dombrowski said that “A common, unusual problem is the reversal of ductwork. People may live in a home for years with the supply air blowing out the returns.

“This is especially noticeable when the home has a central return, so all air is blowing out through the filter.”

Steve Miles added his litany of “typical unusual” problems. “We see all types of things,” said Miles. “For example:

  • “Equipment full of cockroaches;
  • “Other companies that have used a cardboard box and lots of duct tape for a plenum;
  • “Safeties and lockouts bypassed;
  • “Condensing furnaces vented into metal pipe that had completely corroded away;
  • “Water heaters vented downhill;
  • “A/c evaporator coils installed in such a way that all air bypasses the coil;
  • “Furnaces with tripped rollouts because the masonry chimney was full of dead birds — stacked like firewood — because the bird screen had blown away; and
  • “Two furnaces sharing common ductwork but not twinned together.
  • “On the humorous side we had a call for a noisy furnace. It turned out to be a live groundhog that had found its way into the ductwork — and it wasn’t the least bit happy about it.”

Bob Dobrowski said that “The most unusual problem we had was on a call to a medical care center. The building had a roof full of some old Lennox gas packs with direct-ignition heating systems (no pilot). The mechanic was given a call that stated most of the heaters did not work. Yet when he went into the building to meet the customer, it was nice and warm.

“It seems that their ‘friendly maintenance man’ simply went on the roof and dropped lit matches down the flues to get them to heat (or explode). He demonstrated lighting one for our tech, who almost broke his neck running for the roof hatch.

“We sold them a maintenance contract and suggested that they keep their maintenance man off the roof.”

Jo Navaretta said, “Problems that are not as frequent might involve ductwork, where conditioned air is escaping due to poorly sealed ductwork. “These problems are handled the same way as [common ones]. We inform the customer and let them know what needs to be done.”

Tom DiPietro sent in responses from his techs for the most unusual problems they encountered. (These may seem usual to you.)

  • Rodent infestation;
  • Expensive parts found bad;
  • Disconnects off; and
  • Bats found in burner, squirrel in draft inducer — corroded.

It appears that animal remains are unusual and common encounters when inspecting a furnace. In situations like that, it is often due to the fact that the homeowner has not had regular maintenance checks over the years and can probably be sold on a service contract if they are informed of what was decaying in their heating system. So are these common or unusual? Do you have a story to tell The News? E-mail me at and let’s give our service techs an idea of what they might encounter on their next call.