1996 ranger, the temperature control **** which changes from hot to cold dosnt seems to ahve any effect. If I turn on the heater it blows hot air no matter where I rotate the ****. If I put it on AC it blows cool air no matter where I rotate the ****. I would think my control **** its working except it behaves differently if AC is on compared to heat. Would the blend cause this behavior? Or do I have just a bad control **** and AC will blow cold no matter if set to hot or cold. (this is only vehicle that the AC works so I cant compare)

 

I am assuming that your temperature control is vacuum operated since I am not that familiar with the Ranger. Could also be electrically operated which involves potentiometers to control the amount of voltage to the blend door. Can you see if the blend door is moving as you turn the temp control. Probably a vacuum motor so if you apply vacuum directly to the blend door motor you should be able to determine if the problem is in the control or blend door. If the blend door seems to work OK then check for vacuum at the blend door motor as you turn the control. If the problem is in the control, check for vacuum at the control or possibly a vacuum leak at the control. If it is electrically operated you will need to troubleshoot the various electrical components in the climate control system which will require a shop manual and dignostic charts.

John

 

I looked at the blend door. Its either open all the way or closed all the way. Depending if I turn on the heater or the AC. Should it be stopping partialy open at any point? I am amaking an assuption here that the blend door should not just be opened or closed and the variable temperature control **** should adjust the blend door partialy open or closed depending on where the dial is rotated too. Is that how it should work ?

 

Yes the blend door is just that, it blends warm air into the air stream according to the temperature control setting. Max closed or max open when turning the temp control doesn't sound like it is working. Can you tell if the door is free or if it bonds? Blend door issues have been common on FoMoCo products. Also, is it electric powered or vacuum?

John

 

Its vacuum powered, it appears to move freely. Just so I sure we are on the same page. Is the blend door a about 6x8 piece of plastic that I can easily see behind the glove box?

Another piece in info. The AC only works on MAX AC. If I set it to regular AC it blows hot air. What I am calling the blend door dosnt move when changing from regular to MAX AC.

The temperature control **** wires run to a connector that is inside the blower or heater chamber. I can read a variable resitance on that connector when rotating the temperature control ****.

What is inside that box?
What dose it do with differnet resitances?

Thanks!!

 

The blend door is what is inside that box and it sounds like it is electrically controlled since you read a variable resistance. I have copied from the shop manual for my 1999 PSD info that might help you. It may be a little different but it should be close to what you have.

John

"There are two sources of air available to the air distribution system:


outside air
recirculated air
Recirculated air is only used during MAX A/C (if equipped) and OFF modes.

Air distribution within the vehicle is determined by the function selector switch position. Airflow control doors are used to direct airflow within the air plenum chamber. Vacuum control motors are used to position these airflow control doors.

The air distribution system is designed to provide airflow from the defrost nozzle when no vacuum is applied to any of the vacuum control motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak.

Air enters the passenger compartment from the:

instrument panel A/C registers.
heater outlet floor duct.
windshield defroster hose nozzle.
side window demisters.
Passenger compartment air is exhausted from the vehicle through open windows or cab air vents.

Control Components

The manual climate control system heats or cools the vehicle interior depending on the function selector position and the temperature selected. The function selector position determines heating or cooling and air distribution. The temperature blend control setting determines air temperature.

System Components

The manual climate control components are used to:

select the air inlet source (outside or recirculated).
select the blower motor speed.
select the discharge air temperature (temperature blend).
select the discharge air location (defrost, panel, floor).
select the A/C compressor clutch operation.

System Air Flow

SYSTEM AIR FLOW DESCRIPTION
Max A/C
When MAX A/C is selected:

The air inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
The panel/defrost door is at full vacuum and the floor/panel door is in the no vacuum position, directing airflow to the instrument panel A/C register.
The temperature is usually set for maximum cold but may be heated if desired.
Air will be picked up at the recirc opening by the blower motor. With the A/C control set for maximum cold, airflow across the A/C evaporator core will be diverted past the heater core and then directed into the passenger compartment through the instrument panel A/C register.
The A/C compressor will be enabled when MAX A/C is selected.
The blower motor is on.

A/C
When A/C is selected:

The air inlet duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
The panel/defrost door is at full vacuum and the floor/panel door is in the no vacuum position, directing airflow to the instrument panel A/C registers.
The temperature may be raised if desired.
The A/C compressor will be enabled when A/C is selected.
The blower motor is on.

Vent
When VENT is selected:

The air inlet duct door, with no vacuum being applied, will block recirculated air and admit outside air. From there, air flows through the system to the instrument panel A/C registers.
The floor/panel door is in the no vacuum position to block airflow to the heater outlet floor duct.
The panel/defrost door is at full vacuum, closing off airflow to the windshield defroster hose nozzle.
The temperature can be adjusted to heat the air but air cannot be cooled below outside temperature.
The A/C compressor will be disabled when VENT is selected.
The blower motor is on.

OFF
When OFF is selected:

The A/C inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
The panel/defrost door is in the no vacuum position, closing the passage to the instrument panel A/C registers.
The floor/panel door is at full vacuum, closing the passages to the panel/defrost outlets.
The blower motor and the A/C compressor are off.

PANEL/FLOOR
When PANEL/FLOOR is selected:

The air inlet duct door is at no vacuum, blocking the recirculated air passage and admitting outside air.
The panel/defrost door is at full vacuum, closing off airflow to the windshield defroster hose nozzle.
The floor/panel door is in the partial vacuum position, allowing airflow to both the heater outlet floor duct and the instrument panel A/C registers.
The A/C compressor will be enabled when PANEL/FLOOR is selected.
The blower motor is on.

FLOOR
When FLOOR is selected:

The air inlet duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
The floor/panel door is in the full vacuum position, directing all air flow to the heater outlet floor duct.
The temperature can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature level.
The panel/defrost door is in the no vacuum position, blocking air circulation to the instrument panel A/C registers.
The A/C compressor will be disabled when FLOOR is selected.
The blower motor is on.

FLOOR/DEFROST
When FLOOR/DEFROST is selected:

The air inlet duct door is in the no vacuum position blocking recirculated air and admitting outside air.
The panel/defrost door is in the no vacuum position directing airflow to the windshield defroster hose nozzle.
The floor/panel door is in the partial vacuum position, allowing airflow to both the windshield defroster hose nozzle and the heater outlet floor duct. There is also some air flow to the A/C side window demisters.
The A/C compressor will be enabled when FLOOR/DEFROST is selected to dehumidify the air and reduce windshield fogging.
The blower motor is on.

DEFROST
When DEFROST is selected:

The air inlet door is in the no vacuum position, admitting outside air.
Both the panel/defrost door and the floor/panel door are in the no vacuum position so that most of the incoming air is directed to the windshield defroster hose nozzle. There is also airflow to the A/C side window demisters.
The temperature setting will determine the amount of air that is directed through the heater core and the amount that bypasses the heater core.
The A/C compressor will be enabled when DEFROST is selected to dehumidify the air and reduce windshield fogging.
The blower motor is on."