Looking for an office thermostat that actually works? Good luck and Godspeed.

You may never find it. The controls for your company's heating, ventilation and air conditioning (HVAC) are likely hidden in the office ducts. If you do spy a thermostat, it's probably locked, or encased behind shatterproof glass.

Even worse, HVAC experts acknowledge what millions of office workers have suspected all along: A lot of office thermostats are completely fake -- meant to dupe you into thinking you've altered the office weather conditions.

The specialists are unrepentant. Fed up with of complaints from sweaty men and shivering women, HVAC technicians install dummy thermostats to give workers the illusion of control. In some leased buildings, even the corporate tenants don't know the thermostats are useless. Other times, it's the companies themselves, barraged with calls from workers, who ask the landlord's HVAC technicians to "fix" things.

Richard Dawson, an HVAC specialist from Homer, Ill., who has several landlord clients, says too many office workers feel their environment is "anything but what they want it to be." Better to install a dummy when they're out to lunch, he figures. He estimates that 90% of office thermostats are dummies (others say it's below 2%).

Does he feel bad? "I did what my employer told me to do," Mr. Dawson says. The complainers in the cubicles wore him out. "You just get tired of dealing with them and you screw in a cheap thermostat. Guess what? They quit calling you."

Outrageous! As if we haven't been living enough business lies, now this. Thermo-fraud threatens to make more of us look like fools than the New Economy and the disco era combined.

Scott McDaniel, an HVAC technician in North Augusta, S.C., installed a dummy and actually bothered to attach a wire to the back of it -- one that dead-ended into the thin, uncomfortable office air. He hoped the wire would fool the office meddler. "There's always someone who thinks they're a technician," he sighs.

That's just one of several examples where the mere illusion of control seems to satisfy us. Plenty of placebo buttons give the same false impression. That "close door" button on elevators? It won't work unless you're a fireman or an elevator operator with special access to the system. The rest of the time, in deference to various building codes, it's deactivated, according to engineers at Otis Elevator.

That "walk" button at intersections? It tells the system a pedestrian is waiting for a signal, says James Okazaki, assistant general manager of the L.A. Department of Transportation. But that doesn't mean the signal will change faster -- and it may be broken from public abuse. "People keep pushing it, pushing it and pushing it until the signal changes," he says. "You're pushing it like you have a thousand people there but you have one person pushing it 1,000 times!"

Thermostat chicanery goes back about 40 years. Michael Downey, former senior vice president of operations at a commercial real-estate company in New York, first became aware of dummy 'stats in the 1960s. He says some companies went so far as to install white-noise generators to mimic the hum of the fan even though the system was shut off. Later, as heating prices rose, landlords began to write leases specifying a narrow range for air temperatures.

In an attempt to eliminate the human factor and introduce efficiency, many office buildings have replaced thermostats with "thermistors," sensors that read temperature and relay it to a computer that governs the system. But one thermistor can be crowded out by a competing chorus of others, says Paul Milligan, who writes HVAC software programs.

The systems are programmed to allow only a slight variance in temperature. Fiddle all you want, but the computer is saying "do not allow a desired temperature," he says.

The average office worker almost has to be a NASA engineer to get these thermostats working. That's exactly what Scott Packard is. The 39-year-old staff engineer, who works for NASA's Jet Propulsion Laboratory in Pasadena, Calif., has used various illicit techniques to control climate at the different offices he has worked in, including obtaining a rare wrench to remove a thermostat cover.

He and other suffering employees have been known to hold a desk lamps or computer monitor up to the sensor to fool thermostats into turning on the AC. For heat, they strap a baggie full of ice water to it. "I haven't tried to work within the system," Mr. Packard concedes.

Trying to reform, he recently begged for a fan for his JPL office, but "comfort items" can't be purchased with government dollars. So he resorted to his old ways. "I got a ladder and went into the drop ceiling and adjusted dampers to get more cold air," he acknowledges.

Sometimes the stuff is just busted. Vicki Szaszvari, a building-equipment operator for the city of Phoenix, says all the breakdowns are good news for her. "My 2002 truck is paid for," she says. Her license plate: HVAC MAM.

That sounds cold, but Mrs. Szaszvari is compassionate: She once tipped a waitress with a set of keys that unlocked the restaurant thermostat.