I have a Climate Control type HVAC system in my 2003 Envoy. The AC and Heater and all the vents switch from floor to front to defrost as expected. The driver and passenger side temperature control knobs work normal also. It is just that the blower runs irratically, at different speeds on auto and the manual speed control light indicators go up and down in the display panel, but does not control the motor speed. I suspect it might be the Blower Motor Control Module. Is that a good deduction? And if it is, where is the Module located. If it is something else, please advise me. Thanks
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How did you test the A/C system ? Hook up gauge manifold , test A/C pressures ? Manual or automatic climate control ? The blower motor only working on high means the blower motor resistor is bad ! Did you hook up a scan tool an check high an low pressure switchs inputs to the PCM - engine computer . Does the A/C compressor clutch engage ? turning on the compressor ? Moving the mode switch does nothing . Doesn't move from floor to vent to defrost ? Probably the mode door actuator ! Don't think the HVAC control panel is bad . Just a few little things . Pushing the A/C button on the control panel just send a electrical signal to the PCM , the PCM will energize the A/C clutch relay , turning on the compressor .
What A/C problem did you have , original complaint for taking to the dealer ? Does the blower motor blow air out of the vents , when switching from floor to center vent to defrost does air change direction ? What make model an year is your vehicle . Does your vehicle have manual or automatic climate control . Were there any codes stored in the control panel ? Mode door or temperature control problem ? Do you here any clicking behind the dash ?
. Air won't blow out of the floor or center vents just defrost ? Do you have manual or automatic climate control ? Air Flow Control
Air flow control is accomplished in the following manner:
Primary control is through the function selector knob mounted on the A/C-heater function selector switch, which is part of the integrated control panel.
The function selector knob has the following positions: OFF, MAX A/C, A/C, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST. The A/C-heater function selector switch combines a vacuum selector valve with an internal electrical switch.
The vacuum selector valve directs source vacuum to various vacuum control motors (18A318). Refer to the Vacuum Control Diagram , System Airflow Schematics and Vacuum Control Chart .
Two internal, single-pole electrical switches are also controlled by the A/C-heater function selector switch. The combination of these electrical switches controls the electrical supply to the A/C clutch and heater blower motor switch (18578).
The position of the function selector knob determines the manner in which the system will operate.
Each position of the function selector knob is detented for positive engagement.
Vacuum Control Motors
The vacuum control motors (18A318):
are located on the A/C evaporator housing, A/C recirculation air duct and heater air plenum chamber (18471).
direct system airflow to the vehicle interior as determined by the remote climate control module or manual override.
The five-passenger seating configuration has an additional vacuum control motor mounted on the heater air plenum chamber to control airflow to the rear seat A/C register (19893).
REMOVE HEATER BLOWER MOTOR HOT WIRE BLOWER MOTOR IT.IF IT WORKS.YOUR AC AND HEATER CONTROL SWITCH IS FAULTY.CHECK HVAC FUSES AND CHECK BLOWER MOTOR RELAY.IF BLOWER MOTOR DONT WORK WHEN HOT WIRE REPLACE IT.IF ALL CHECK OUT GOOD.HAVE DEALERSHIP DO A DIAGNOSTIC TEST ON YOUR CLIMATE CONTROL SYSTEM.
MAKE SURE BLOWER MOTOR OPERATING IF NOT CHECK FUSE AND RELAY.ALSO CHECK HVAC FUSE THIS CONTROL HEATER + AC CONTROL SWITCH AND MODE SELECTION FOR OPENING AND CLOSING HEATER DOOR OR HEATER CONTROL VALVE AND AC+ DEFROST AIR DOOR.IF BLOWER AND HVAC FUSE OKAY.IF YOU HAVE MANUAL HEAT CONTROL MAKE SURE MODE SWITCH IS RECEIVING VACUUM. YOU HAVE TO REMOVE HEATER CONTROL SWITCH AND CHECK TO SEE IF GETTING VACUUM GETTING TO SWITCH LOOK FOR BROKE DISCONNECTED VACUUM LINES IN THE DASH AREA.IF YOU HAVE CLIMATE CONTROL.YOU COULD HAVE A FAULTY ELECTRICAL HEAT DOOR ACTUATOR.SOME CLIMATE CONTROL CARS HAS THE CLIMATE CONTROL PROGRAMMER HAS TO BE REPROGRAM BEFORE THE HEATER AND AC WILL WORK AGAIN.YOU NEED A DEALERSHIP SCANNER TO CHECK IT OUT.BUT IF YOU HAVE MANUAL CONTROL CHECK TO SEE IF YOU GETTING VACUUM.IF YOU GETTING VACUUM AT HEATER DOOR VACUUM ACTUATOR OR HEATER CONTROL VALVE EITHER ONE OF THOSE COMPONENTS COULD BE FAULTY.WARNING YOUR VECHICLE HAS AIRBAGS YOU HAVE TO DISARM THEM BY REMOVING FUSES WAIT 20 MINUTES BEFORE WORKING ON DASH AREA.YOU HAVE TO CRANK CAR UP TO CHECK TO SEE IF YOUR HVAC GETTING VACUUM.
first check to see if you have power going to the actuators when you switch the switch to it location if no power replace controller if you have power and no movement from actuators replace actuator. if actuators move remove hvac box and check for broken blend doors.
Need to check to see if the blower motor is running.If it is,but not threw the vents,most likely a vent door actuator motor.The actuator motor in this case would be bad,it is hard to get to,unless you are mechanically inclined,You can do it your self.If the blower motor is bad,just replace it.Check fuses first,and the blower relay.If I can help,let me know.
sounds like you have two problems, if there is no air from front then you need to ck power to your blower motor, if no power you need to ck your blower resistor and connector, second if no cool air from rear your compressor may not be engaging, make sure you ck your fuse for the front hvac system.
ok could be one of 3 things. 1 you may be out of freon. (proly spelt that wrong) 2. compresser could be bad. 3 the clutch on your compresser might not be engaging. when trucks running turn ac on and see if the front of your compresser spins or not. if it does clutch is good. but it could be that your compresser is still bad. either way i recomend you go for freon and start there. when they fill it they will tell you for sure wether or not your compresser is bad.