HVAC - General Servicing: Overview Toyota Sequoia I

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1. Inspect refrigerant volume: Observe the sight glass on the liquid tube. Test conditions: Running engine at 1,500 rpm. Single A/C: Front blower speed control dial at "HI" position. Dual A/C: Front and rear blower speed set at "HI" position. A/C switch ON. Single A/C: Front temperature control dial at "MAX. COOL" position. Dual A/C: Front temperature control dial at "MAX. COOL" position. Rear temperature control set at 18.5 °C (65°F). Fully open the doors.
2. . Inspect refrigerant pressure with manifold gauge set: Test conditions: Temperature at the air inlet with R/F switch set at RECURC is 30 - 35 °C (86 - 95 °F). Engine running at 1500 rpm. Blower speed control switch at "HI" position. Temperature control dial at "MAX. COOL" position. Dual A/C: Rear temperature control set at 18.5°C (65°F). For normally functioning refrigeration system diagnosis, see illustrations. For normal gauge readings (Scheme 5)- (Scheme 7). For moisture present in refrigeration system diagnosis, see illustrations. (Scheme 8)and (Scheme 9). For insufficient cooling diagnosis, see illustrations. (Scheme 10)and (Scheme 11). For poor circulation of refrigerant diagnosis, see illustrations. (Scheme 12)and (Scheme 13). For refrigerant does not circulate diagnosis, see illustrations. (Scheme 14)and (Scheme 15). For refrigerant overcharged or insufficient cooling of condenser diagnosis, see illustrations. (Scheme 16)and (Scheme 17). For air present in refrigeration system diagnosis, see illustrations. (Scheme 18)and (Scheme 19). For expansion valve improperly diagnosis, see illustrations. (Scheme 20)and (Scheme 21). For defective compression in compressor diagnosis, see illustrations. (Scheme 22)and (Scheme 23).
3. Inspect idle-up speed Warm up engine. Inspect idle-up speed when the these conditions are established. Warm up engine. Blower speed control switch at "HI" position. A/C switch ON. Temperature control dial at "COOL" position. If idle speed is not as specified, check Idle control system. (Scheme 24)
4. Inspect for leakage of refrigerant. Perform in these conditions: Stop engine. Secure good ventilation (If not the gas leak detector may react to volatile gases witch are not refrigerant, such as evaporated gasoline and exhaust gas.) Repeat the test 2 or 3 times. Make sure that there is some refrigerant remaining in the refrigeration system. When compressor is OFF: approx. 392 - 588 kPa (4 - 6 kgf/ cm 2, 57 - 85 psi) NOTE: After the blower motor stopped, leave the cooling unit for more than 15 minutes. Expose the gas leak detector sensor the under the drain hose. When bring the gas leak detector close to the drain hose, make sure that the gas leak detector does not react to the volatile gases. If such reaction is unavoidable, the vehicle must be lifted up. Bring the gas leak detector close to the drain hose before performing the test. If gas leak is not detected on the drain hose, remove the blower motor linear controller from the cooling unit. Then insert the gas leak detector sensor into the unit and perform the test. Disconnect the connector and leave the pressure switch for approx. 20 minutes. Then bring the gas leak detector close to the pressure switch and perform the test. Bring the gas leak detector close to the refrigerant lines and perform the test.

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1. Connect quick disconnect adapter to charging hoses. (Scheme 25)
2. Remove caps from service valves on refrigerant lines.
3. Set on manifold gauge set. Close both hand valves of manifold gauge set. Connect the quick disconnect adapters to the service valves.
4. Evacuate air from refrigeration system. Connect the vacuum pump adapter to the vacuum pump. (Scheme 26) Connect the center hose of the manifold gauge set to the vacuum pump adapter. (Scheme 27) Open both the high and low hand valves and run the vacuum pump. NOTE: If the reading 750 mmHg (30 in. Hg) or more, close both hand valves of manifold gauge set and stop the vacuum pump. Check the system for leaks and repair necessary. After 10 minutes or more, check that the low pressure gauge indicates 750 mmHg (30 in. Hg) or more. Close both the high and low hand valves and stop the vacuum pump. Leave the system in this condition for 5 minutes or more and check that there is no change of gauge indicator.