Hello! We are working on a Peugeot 307 2006 year two zone air conditioning system. If I want to change the desired temperature from 18,5 deegre to 19 , it jump to 15 , and start to cool. The main circuit board in the dash was replaced earlier , w/o result. Any idea from somebody ? Thanks, Andras

A heater core is a component inside the HVAC box (located under the dash) that is heated by engine coolant. Vent temperature is increased by routing air through the heater core before it comes out of the vents. The temperature requested by the HVAC control module determines how much air passes through the heater core and how much air bypasses it. This event is called air "mixing" or "blending" which refers to the hot air and cold air ratio. Air routing through and/or bypassing the heater core is carried out by the use of a blend door and blend door actuator. Over time these two components can fail mechanically which often results in abnormal noises and improper positioning leading to undesired temperatures. Now, higher-end A/C systems with dual-zone climate control have multiple blend doors and actuators; this is how how the two different temperature "zones" are achieved. A failure with only one of the zone's blend door/actuator would result in desired temperature out of one zone's vents and abnormal temperature out of the other zone's vents. You can read more here: https://www.yourmechanic.com/article/what-is-the-difference-between-climate-control-and-air-conditioning

Does your car have dual-zone climate control?

It sounds like you have "zone" climate control. With "zone" climate control you can adjust the driver, passenger and sometimes other "zones" to different temperatures for the comfort of all passengers. Make sure that the Driver side is set to a cool temperature. If it is then you more than likely have a problem with the temperature controller for the driver side.

Hi there,

There are 2 types of Air-conditioning fitted to vehicles:

1) Manual Air - this is where you turn your temp dial to either Cold (Blue) or Hot (Red) and the heater will continue produces the same temperature at all times, until you manually change the setting.

2) Auto/Climate Air-conditioning - this is the INTELLIGENT aircon system, with many sensors placed around the car's interior. This system allows you to select your desired temperature in degrees (e.g. 18 deg C). Once you have chosen your desired temperature, the system then measures the inside temp at each sensor location. The sensor readings are sent back to your aircon computer and this is where the magic happens:

The computer then directs a priority airflow to the areas of your vehicle which would enable the system to reach 18 degrees, in the shortest possible time (this is why airflow changes between various vent outlets). As the system approaches your desired temperature, you will notice the airflow will slow down just enough to maintain a comfortable 18 deg - this is why they call it CLIMATE aircon.

However, if you choose to override the vent direction (i.e. selecting face vents only), they system will take a couple of seconds to respond to your command.

Cheers,



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Yes , the Refrigerant level is good , I would say the control panel is bad , or there is a problem with HVAC Air Delivery/Temperature Control Circuit Description
The vacuum actuators move the air valves in the HVAC system (except the temperature valve). Vacuum is applied to the actuators through the mode selector in the heater A/C control assembly. The mode selector consists of a rotary vacuum switch. The rotary vacuum switch supplies vacuum to the vacuum actuators according to the operating mode selected by the driver. A small servo motor moves the air temperature actuator. The small servo motor positions the door according to the voltage level from the temperature selector in the heater A/C control assembly. The temperature selector is a potentiometer positioned by the temperature control knob on the front of the heater A/C control assembly.
Air Temperature Actuator
When the ignition switch is in the RUN position, battery voltage is applied to the air temperature actuator. The actuator receives ground at all times through the following components:
• CKT 251
• Ground G204
The temperature selector is a potentiometer with a wiper arm. The wiper arm is electrically tied to the air temperature input through CKT 733.
When the temperature selector is moved between COLD and HOT, voltage to the control input varies between 1 and 12 volts. The temperature valve motor solid state circuitry performs the following tasks:
• Looks at the control input voltage
• Moves the motor to correspond to the control input voltage
The temperature valve moves for the following reasons:
• In order to allow the air to pass through the heater core
• In order to allow the air to pass around the heater core
This control achieves the desired passenger compartment temperature.

HVAC Air Delivery System Check
Step
Action
Yes
No
1
Start the engine.
Turn the blower motor fan ON and select an air outlet mode.
Does air flow out of the selected HVAC outlet ducts?
Go to Step 3
Go to Step 2
2
Did the customer concern mention that the air discharges out the correct ducts at first, but then changes during higher engine RPM?
Go to Step 7
Go to Step 3
3
With the engine running, cycle the HVAC controls through all the modes.
Does the air come out of the selected outlet ducts?
Go to Step 18
Go to Step 4
4
With the engine running, take a vacuum reading at the manifold vacuum port that supplies vacuum to the HVAC vacuum control assembly.
Is there engine vacuum?
Go to Step 6
Go to Step 5
5
Repair the no vacuum condition.
Is the repair complete?
Go to Step 18
--
6
Take a vacuum reading at the vacuum supply line at the HVAC vacuum control assembly.
Is the vacuum reading the same as the engine vacuum?
Go to Step 11
Go to Step 8
7
Disconnect the vacuum supply line from the HVAC vacuum control assembly.
With the vacuum gauge connected to the vacuum supply line, re-start the engine and turn the engine OFF.
Does the system lose vacuum after turning OFF the engine?
Go to Step 8
Go to Step 11
8
Inspect for leaking or collapsed vacuum lines between the engine manifold vacuum port and the HVAC vacuum control assembly.
Are the vacuum lines leaking?
Go to Step 9
Go to Step 10
9
Repair or replace the collapsed or leaking vacuum line.
Is the repair complete?
Go to Step 18
--
10
Replace the vacuum reservoir tank.
Is the repair complete?
Go to Step 18
--
11
Using an external vacuum source, apply vacuum to the appropriate vacuum line at the connector to the HVAC vacuum control assembly.
Does the actuator retract?
Go to Step 17
Go to Step 12
12
Inspect for leaking or collapsed vacuum lines between the actuator and the connector to the HVAC vacuum control assembly.
Are the vacuum lines leaking?
Go to Step 9
Go to Step 13
13
Disconnect the vacuum line from the actuator.
Apply an external vacuum source to the actuator.
Did the actuator retract?
Go to Step 14
Go to Step 16
14
With the actuator disconnected, inspect the door for binding.
Does the door move freely?
Go to Step 16
Go to Step 15
15
Repair the appropriate binding door.
Is the repair complete?
Go to Step 18
--
16
Replace the appropriate vacuum actuator.
Is the repair complete?
Go to Step 18
--
17
Replace the HVAC vacuum control assembly.
Is the repair complete?
Go to Step 18
--
18
Cycle the HVAC controls through all modes to verify proper operation.
Did you correct the condition?
System OK
--

Engine is difficult to start when cold

1. Check the battery condition, battery state of charge and starter motor current draw. Replace the battery if marginal and the starter motor if the current draw is beyond specification.
2. Check the battery cable condition. Clean the battery terminals and replace corroded or damaged cables.
3. Check the fuel system for proper operation. A fuel pump with insufficient fuel pressure or clogged injectors should be replaced.
4. Check the engine's tune-up status. Note the tune-up specifications and check for items such as severely worn spark plugs; adjust or replace as needed. On vehicles with manually adjusted valve clearances, check for tight valves and adjust to specification.
5. Check for a failed coolant temperature sensor, and replace if out of specification.
6. heck the operation of the engine management systems for fuel and ignition; repair or replace failed components as necessary.

Engine is difficult to start when hot

1. Check the air filter and air intake system. Replace the air filter if it is dirty or contaminated. Check the fresh air intake system for restrictions or blockage.
2. Check for loose or deteriorated engine grounds and clean, tighten or replace as needed.
3. Check for needed maintenance. Inspect tune-up and service related items such as spark plugs and engine oil condition, and check the operation of the engine fuel and ignition management system.

The FAN SENSOR CONTROL.
This device is disclosed which causes a fan of a heating and/or air conditioning system to continue to run until the temperature in the duct work of the system reaches a desired temperature, so as to remove all heated and/or cooled air from the system, however, the device is designed so as to not cause the fan to be actuated due to changes in the duct work temperature which are due to changes in outside temperature or causes other than the operation of the system. A sensor which is located in the duct work controls the operation of the fan in response to temperature changes only if the sensor control circuit is first energized by the operation of the system.

Hope help with this (remember rated this help).

IT COULD BE THAT THE RADIATOR FAN IS NOT WORKING CAUSING THE HIGH PRESURE SAFETY SWITCH TO ACTIVATE ALSO CHECK FOR DEBRIES BETWEEN THE RADIATOR AND CONDENSOR

IT SOUNDS LIKE THE THERMOSTAT IS FAULTY OR COULD BE THE FRONT FAN IS NOT WORKING IF THE FAN DOES NOT WORK THE SYSTEM OVER HEATS AND THE HIGH PRESURE SWITCH WILL CUT OUT THE SYSTEM