Microcomputer air conditioner control circuit

The working principle of the circuit is as follows: The Hui Computer air-conditioning control circuit is shown in Figure 1-58. The main control chip uses the AT89C52 microcontroller. When the power is turned on
, the microcontroller first reads the last saved operating status data of temperature, constant value and wind speed from 24C02, and then relaxes in the standby state. Press
the "On/Off" button SB once. . The air conditioner starts to run, and the fan runs in the same state as last time. The thermistor RTl detects the indoor temperature change, and
after ryD conversion processing, the current actual temperature value is displayed on the digital tube. The display range is -20- -+40'C, when the temperature is lower than the set value
, P3.5 outputs low level and the compressor does not operate. When the temperature is higher than the set value and P2.5 pin is low level, P3.5 outputs high level Level, K4
amplifier, compressor starts to work. ICZ, VD1, G, form a compression sail to protect the electric gizzard. When the compressor is working, since P.5 is
high level , the voltage is charged by IC2, VD1 and G, making P2.5 high level. When the compressor is working, When the compressor stops, P3 and 5 are at low level. At this time, cl
discharges the product, so that P2.5 remains high for a period of time (about 3 minutes). During this process, the compressor will not start again, thus This avoids
damage caused by frequent compressor starts due to instantaneous power outages, protection, incorrect operation, and use in environments with large temperature fluctuations.
    During operation, the microcontroller also continuously detects the level of the power supply voltage through RP1. If it is lower than 190V or higher than 270V, the air conditioner will stop
working and the error message "E01" will be displayed. It will continue to work when the voltage is normal. I is installed in the lower part of the evaporator at the position of the evaporator 2tn/0!.
When the outlet glass refrigerant leaks, is clogged, etc.,... Serious frost will appear in the lower part of the evaporator. When the frost thickness is greater than 2 mtn., tRT2 will touch
the frost and feel a lower temperature. The microcontroller will detect this information and cause the air conditioner to stop working and display an error message. "E02 is stretched, prompting
the user to perform maintenance. SBlr is the wind speed setting key. During operation, press SB1 continuously, Ki, K2, and K3 will close in sequence. Connect
the low-speed, medium-speed, and high-speed windings of the fan respectively to make the fan press Run at the corresponding speed. SBZ and SB3 are temperature setting keys. Press SB2 or
SB3 during operation, and the digital tube will change from displaying temperature to displaying the temperature set value. At this time, press _ and S, and the set temperature will increase by 1 ℃, press SB3, decrease
1℃', the setting range is 1S~30℃: After stopping pressing the button for 1Os, the digital tube changes to display the current temperature value. When it is necessary to shut down, press
SB4. The microcontroller will change the current temperature The set value and fan operating status data are stored in IC9 for saving, and then stopped.