Question about 1998 Oldsmobile Bravada
The issue with this vehicle has nothing to do with the heater control valve it is working fine. the issue is the blend door motor is turning to hot all the time. When I adjust the temp knob it wont cool down at all. I pulled the blend motor out and it is always spinning to hot, new motor does the same thing and the control head is replaced also.
Check your vacuum lines to the actuators. Specially the ones for solenoids 2 and 3. Check solenoid operation.
AUTOMATIC CLIMATE CONTROL OPERATION The automatic climate control consists of four major systems. Refrigeration system, heater system, air distribution system and A/C-heater control modes. Interior temperature, blower motor speed and mode of operation can be selected from the A/C-heater control module. In AUTO mode, the system determines appropriate air intake and discharge positions, blower motor speed and discharge air temperature according to operator selected temperature and information provided by the system's sensors. See SENSORS. The A/C indicator light will come on when in AUTO mode. If a function is selected but not available in a particular mode of operation, the indicator light beside the chosen function will blink three times, indicating unavailable in this mode. Try choosing another mode and selecting function again. Direction of airflow to vents and outlets is controlled by 6 actuators, one electronic controlled actuator and 5 vacuum controlled actuators. The electronic actuator moves the air mix door, vacuum actuators control the inlet door and 4 mode doors. See ACTUATORS.
A/C-HEATER CONTROL MODULE Blower Motor Control Knob When blower motor control knob is set to AUTO mode, blower motor speed is determined by the blower control module and its network of sensors. When blower motor control knob is rotated from AUTO to OFF position and beyond, blower control module switches to manual mode. In manual mode, 13 speeds can be selected with the blower motor control knob. Blower motor speed remains the same until a new speed is selected by operator. When blower motor control knob is OFF, some air will enter vehicle when vehicle is moving THE FOLLOWING DIAGRAMS WILL HELP YOU TO LOCATE AND FIX YOUR PROBLEM. CHECK OPERATION OF ALL ACTUATORS
I have a heat issue. I have tackled a lot of auto - 51cdc4f.gifBLE TO TEST DIFFERENT SOLENOIDS
MAKE SURE THE TEMP CONTROL DOOR ACTUATOR IS WORKING
KEEP ME POSTED.
Posted on Oct 14, 2010
There are two types of heater door actuator, one is for the manual controller and the other is the automatic controller. it sounds like the wrong actuator may have been installed in to your Bravada.
There are several possible problems. The most likely, is that one of the gears in the blend door actuator is cracked. Therefore, the blend door is stuck in one position. The actuator CAN be accessed through the glove box but it is tight. On the left hand side you will see a vacuum controlled lever. That is for the defrost (if you turn the truck on and switch the vent position switch back and forth you will see it move). The blend door actuator is behind that so its easier to remove that vacuum diaphragm to gain access. The overdrive problem mentioned earlier could also be a problem. To reset this, turn the truck off, remove the RDO fuse for 30 seconds, replace the fuse, then turn the key to the run position. This will start a calibration cycle to reteach the computer where the maximum and minimum rotation points are so that it doesn't overdrive. If, after doing this procedure, the hvac system cycles back and forth from heat to cool there is probably a code set in the Climate Control Module and it may be time to get a dealer with a scan tool involved. On my truck and at least one other truck I have found out about, the control module is unable to sense the location of the actuator door (that is what causes it to "overdrive"). You can verify if your module is overdriving by removing the blend door actuator but leaving the electrical connector on. Turn the truck on, cycle to heat. The visible gear should rotate one direction then stop. Cycle to cool. The gear should rotate the other way and then stop. If it doesn't stop there may be something wrong with the control module. I hope this long-winded post helps someone.
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Posted on Oct 10, 2010
Do a compression check on the motor to see if you have high compression on 1 or more cylinders. If so you most likely have a bad Head gasket or other problem allowing the engine to create too much pressure on the radiator lines which forces the heat control valve open. Check the heat control valve on the 1 inch line that goes from the engine to the Firewall supplying hot water to the heater core. If that is locked in the open position it will give you this symptom.
Posted on Oct 11, 2010
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Posted on Jan 02, 2017
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