Mercedes Benz 300D Climate Control

25 мая 2015 | Author: | No comments yet »
Mercedes-Benz F 300

Questions and Answers

Mercedes 300D Climate Control

Q. Hi I have a 1978 Mercedes 300D which I just Heater/AC worked fine on 500 drive home. Now it works Sometimes everything is fine, but of the time when I press the or bi-level button either happens or defrost puts out of hot air. Defrost button gets hot air only even if happens when pressing buttons.

Cannot get cold air defrost even though the A/C is engaged. When the system is it puts out lots of cold Could this be a blower problem, or control unit, or

Thanks for your help.

A. How I give you the Description and Operation of the and you can compare it to how yours is working? if there is a problem we can try and troubleshoot it.


The Automatic Climate Control push-button control unit:

the air distribution system.

Activates the A/C blower motor, auxiliary pump and mono valve.

necessary corrections to maintain air temperature and blower speed at levels.


Temperature :

The temperature wheel provides interior temperature control in a range from approx. (16°C) to 89°F (32°C). If the wheel is set at MIN, the system at full uncontrolled cooling If the system is set at the MAX position, the system at full uncontrolled heating

Rotation of the temperature wheel the resistance (potentiometer), transmitting the new value into the electronic of the temperature control.

Blower :

The blower switch operates in six The top button (f) is maximum setting (6) and full 12 volts. The bottom (h) is minimum setting (1) and delivers 4 The center button (g) is automatic (2-5) and delivers between 5 and 10 In AUTOM the blower will in 2nd stage after 10 seconds in b, c, and d. The blower will switch up to 5th if required.

Function Controls

Defrost a

The starts immediately in the 6th stage the ignition is switched on. Regardless of the dial, maximum heated air is to the windshield.

The recirculating (auxiliary pump runs continuously and the is switched on at outside temperatures +2°C.

Top/Bottom Air Distribution b

The starts after approx. 10 even with coolant below +35°C in AUTOM in 3 to 5.

Mercedes-Benz F 300

Air is routed to the windshield, side, and vents in heating range; and the center vent in cooling This operation removes if any, from the windshield damp,cold weather.

Bottom Air Distribution c

The blower immediately set to AUTOM in stages 3 to 5 if the temperature is approx. 4°C higher the temperature dial setting.

air will flow out the legroom and nozzles with a leak air from defroster vents in range.

Cooled air flows out of and side nozzles only in range. The mode changes (heating to cooling) and it is possible for vents and center vents to with heated and cooled air and be simultaneously.

The compressor switches on at above +2°C and the evaporator is to approx. 0°C. If the system to cooling the fresh air/recirculating air is switched to recirculating air.

Economy d

In Economy (EC) the operates with fresh air

Heated air flows out of legroom and nozzles with a leak air from defroster vents in range.

Air is routed to center and vents only during range. The blower operates in 3 to 5 in AUTOM. The blower is not switched on coolant temperature reaches

Off e

In Off the air supply is switched off through the air flap to the inside of vehicle. The system continues to operate driving and the monovalve remains Blower does not operate.

If acts as described, then it is If not, then it is most a bad control unit of a loose to the control unit.

Mercedes-Benz F 300
Mercedes-Benz F 300
Mercedes-Benz F 300

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