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Discussion Starter · #1 ·
hey i need some help. i managed to loose my wires going to my actuator. or do i even have wires going to it. the dern thing wont turn from hot to cold. i got under the dash and looked and looked but i was unable to find any thing. the vacum actuator works but only only when switched to max ac. please help me out on this. i have the normal heat and ac system.
 

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what year? is it a simple heat and ac panel or the one with auto climate control?
 

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Discussion Starter · #3 ·
just the simple heat and ac panel
 

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what year is your blazer?
 

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Air Temperature Description and Operation 4.3L
The air temperature controls are divided into 4 areas:

HVAC Control Components
Heating and A/C Operation
Engine Coolant
A/C Cycle
HVAC Control Components
HVAC Control Assembly
The HVAC control assembly is a non-class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive and ignition 3 voltage circuits provide power to the control assembly. Two integrated potentiometers control air temperature door position and blower motor speed. The integrated vacuum system controls the mode door position. The control assembly supports the following features:

Feature
Availability

Afterblow
No

Purge
No

Personalization
No

Actuator Calibration
No

Air Temperature Actuator
The air temperature actuator is a 3-wire bi-directional electric motor. Ignition 3 voltage, ground and control circuit enable the actuator to operate. The control circuit uses a 0-12 volt linear-ramped signal to command the actuator movement. The 0 and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between 0-12 volts correspond to the positions between the limits.

When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed. When full cold is selected, a low voltage, near ground, is applied to control circuit. When full hot is selected, a high voltage, 12 volts, is applied to the control circuit.

A/C Pressure Switches
Two pressure sensors protect the A/C system. If the A/C low pressure falls below 145-172 kPa (21-25 psi), then the A/C low pressure switch will open. This will disable A/C compressor operation. This switch will then close at 262-290 kPa (38-42 psi) to allow A/C operation. If the A/C high pressure exceeds 2826 kPa (410 psi), then the A/C high pressure switch will open and not allow for the PCM interpret an A/C request. This switch will close at 2413 kPa (350 psi).

Heating and A/C Operation
The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature:

Recirculation actuator setting
Difference between inside and desired temperature
Difference between ambient and desired temperature
Blower motor speed setting
Mode setting
The control assembly makes the following actions when an air temperature setting is selected:

When the air temperature switch is placed in the warmest position, the control assembly commands the air temperature door to divert maximum air past the heater core.
When the air temperature switch is placed in the coldest position, the control assembly commands the air temperature door to direct air to bypass the heater core.
The mode switch must be placed in the following positions for the A/C to be engaged by the PCM.

Max A/C
A/C
Bi-Level A/C
Blend
Defrost
The following conditions must be met in order for the PCM to turn ON the compressor clutch:

Engine coolant temperature (ECT) is less than 121°C (250°F)
Engine RPM is more than 550 RPM
A/C low pressure switch signal circuit is grounded
A/C request signal circuit to the PCM has 8.5 volts or more
Once engaged, the compressor clutch will be disengaged for the following conditions:

Throttle position is 100 percent
A/C request signal circuit has 0 volts
A/C low pressure switch signal circuit has voltage
Engine coolant temperature (ECT) is more than 121°C (250°F)
Engine speed is more than 5,500 RPM
Transmission shift
PCM detects excessive torque load
PCM detects insufficient idle quality
PCM detects a hard launch condition
When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.

Engine Coolant
Engine coolant is the essential element of the heating system. The thermostat controls the normal engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation.

Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The ambient air drawn through the HVAC module absorbs the heat of the coolant flowing through the heater core. Heated air is distributed to the passenger compartment, through the HVAC module, for passenger comfort. Opening or closing the air temperature door controls the amount of heat delivered to the passenger compartment. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.

A/C Cycle
Refrigerant is the key element in an air conditioning system. R-134a is presently the only EPA approved refrigerant for automotive use. R-134a is a very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air.

The A/C system used on this vehicle is a non-cycling system. Non-cycling A/C systems use a high pressure switch to protect the A/C system from excessive pressure. The high pressure switch will OPEN the electrical signal to the compressor clutch, if the refrigerant pressure becomes excessive. After the high and the low sides of the A/C system pressure equalize, the high pressure switch will CLOSE. This completes the electrical circuit to the compressor clutch. The A/C system is also mechanically protected with the use of a high pressure relief valve. If the high pressure switch were to fail or if the refrigerant system becomes restricted and refrigerant pressure continues to rise, the high pressure relief will pop open and release refrigerant from the system.

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure on the vapor refrigerant. Compressing the refrigerant also adds heat. The refrigerant is discharged from the compressor through the discharge hose, and forced through the condenser and then through the balance of the A/C system.

Compressed refrigerant enters the condenser at a high-temperature, high-pressure vapor state. As the refrigerant flows through the condenser, the heat is transferred to the ambient air passing through the condenser. Cooling causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line to the orifice tube.

The orifice tube is located in the liquid line between the condenser and the evaporator. The orifice tube is the dividing point for the high and the low pressure sides of the A/C system. As the refrigerant passes through the orifice tube, the pressure on the refrigerant is lowered, causing the refrigerant to vaporize at the orifice tube. The orifice tube also measures the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the orifice tube flows into the evaporator core in a low-pressure, liquid state. Ambient air is drawn through the HVAC module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant to boil inside the evaporator core. The boiling refrigerant absorbs heat from the ambient air and draws moisture onto the evaporator. The refrigerant exits the evaporator through the suction line and flows back to the compressor in a vapor state, completing the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the HVAC module for passenger comfort. The heat and moisture removed from the passenger compartment condenses, and discharges from the HVAC module as water.
 

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Discussion Starter · #6 ·
last year i pulled the whole dash out and changed out the heater core, that is why i'm thinking i lost the wires in the process. the only other thing i can think of that i done is i unhooked the ac compressor cause its bad. and its a 01
 
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