If your window-mounted air conditioning unit is not responsive to your changes in temperature settings at the control panel, then it may be due to incorrect readings in the unit's temperature sensor. This problem can cause your unit to run longer than necessary or shut down too early. Below is how to restore your window unit to its fully-functioning state:
How your window unit monitors and adjusts for temperature
Window air conditioners depend on a temperature sensor mounted beneath the filter but just in front of the unit's evaporator coil. This sensor, also commonly called a thermistor, is tasked with measuring the ambient air temperature; it is electronically-connected to the unit's board where signals are received and interpreted by the circuitry.
The unit then responds by comparing the actual temperature to the desired temperature set by the user and either cycles the compressor on or off to adjust the cold air output. This system normally works well, but problems can arise and can cause inaccurate temperature readings. A couple of common problems and their fixes are given below:
Air circulation dynamics
The window unit's temperature sensor can be fooled by the flow of air from the unit itself due to environmental factors. For example, a window unit with low-hanging blinds or drapes that cover part of the front of the vent registers can experience a blowback of cold air into the front of the unit. This causes the unit to turn off prematurely even though the area removed from the immediate front of the air conditioner is still warm. Here are a few considerations that can help correct poor circulation in the unit's airflow:
Keep drapes pulled away from the unit - use tiebacks to keep drapes and curtains well-away from the outgoing air. If the drapes are moving more than a tiny amount, it is possible they are disturbing the airflow and distorting temperature readings.
Hang wet clothing several feet away from the front of the unit - while a window air conditioner can serve as an effective clothes dryer, hanging clothing too close to the unit can cause airflow disturbances that affect temperature monitoring.
Do not block vents with furniture or other objects - stacking boxes or moving home furnishings in front of the air conditioner is another source of air circulation distortion. Keep the immediate floor space and wall space in front of a window unit clear.
Dirty temperature sensor
If you determine that air circulation in front of the window unit seems normal and is unobstructed, then you should take the next step to check and clean the temperature sensor. This is an easy procedure and should be performed at least once per year to ensure accuracy. Here are the steps:
1. Unplug the unit from the wall - air conditioners carry lethal voltages and can electrocute careless persons. Never open a unit still plugged-in and be careful not to touch any capacitors inside the unit to avoid painful shocks.
2. Remove front panel of the unit - most window units contain a front access panel that covers the air filter element. Look for tabs that need to be depressed while lifting the panel and be careful not to press too hard in order to avoid breaking the plastic. Once the panel is removed, set it aside in a safe place.
3. Remove the filter - the next layer beneath the front panel is the unit's washable filter. This filter usually simply pulls away from the unit; set it aside until later.
4. Locate the temperature sensor - the temperature sensor will appear as a small bulb attached to a couple of wires and will be clipped to the front of the condenser. Carefully pull the bulb from the mount, but do not yank it from its position or accidentally pull its wires out of the control board.
5. Clean the temperature sensor - once you have accessed the temperature sensor, inspect it for any visual signs of damage such as chips, scrapes, and nicked or cut wires. If it appears to be in operable condition, soak a clean microfiber cloth with isopropyl alcohol. Wipe the sensor and its wires with the damp cloth to remove any residue that might be causing problem.
6. Restore the sensor, filter and panel - after cleaning the sensor thoroughly, reinstall it into position and also replace the filter and front panel. Plug in the unit and test it for proper functioning. Check out sites like http://www.belairplumbing.com for more info.