1995 Volvo 850 Auto AC Heater Systems (ECC)
The Electronic Climate Control (ECC) module (A/C-heater control panel) contains a function selector dial, driver’s and passenger’s temperature dials, a REC (recirculated air) switch, A/C OFF switch, and a fan speed (blower motor) control lever. See Fig. 1. The heater (blower motor) fan is controlled by ECC output (power) stage. Air conditioning system will only operate above 32 £ F (0 £ C). Blower switch must not be in zero position to allow compressor to engage.
Other system components include an A/C relay, A/C compressor, low-pressure switch (pressostat), A/C safety and high-pressure switch, engine coolant temperature sensor, outside temperature sensor, interior temperature sensors, and duct temperature sensors.
In addition, driver’s and passenger’s temperature control damper motors, recirculation damper motor, floor/defroster damper motor, ventilation damper motor, and diagnostic connectors (units) complete system.
The A/C compressor electromagnetic clutch is powered by the A/C relay. Compressor operation requires that the A/C relay be activated by both Electronic Climate Control (ECC) module and Engine Control Module (ECM). The ECM turns A/C compressor off when engine is at full acceleration, at high engine temperature, and for 5-10 seconds after starting engine.
The ECC control module normally supplies voltage to A/C relay, except when heater (blower motor) fan is off and vehicle speed is less than 20 MPH, when heater fan is off and recirculation is on, or momentarily when under full acceleration.
If A/C is switched off using the AC OFF switch, ECC control module will cut supply voltage to relay, turning off compressor. However, this does not apply when air distribution control is in defrost setting, since A/C is always on in this case.
Get pdf 1995 Volvo 850 Auto AC Heater Systems (ECC)
