Testing the regulation and heat output - ra83001400160x(0160)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Model 140 with automatic heater control

Operation no. of operation texts and work units or standard texts and flat rates:

Fig 1: Testing Regulation

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Testing regulation

Test conditions	Note (figures 1 to 5).
Regulation	Test. Nominal value 22 ± 1°C after driving for 10 - 15 minutes, with the left and right selectors positioned on the center "white" area. Blower stage "2" and air distributor switch at "4 o'clock position" (figures 6 to 12).

Fig 2: Testing Regulation

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Testing heat output

Test conditions	Note (figures 1 to 5).
Heat output	Test (figures 13 to 15). After the engine has been running at approx. 2000 rpm for 5 min., the nominal value is above 55°C when the selectors on the left and right are engaged on "RED", blower stage 4 and air distributor switch at the "12 o'clock position".

COMMERCIALLY AVAILABLE TOOLS

Digital temperature measuring equipment with 4 measuring probes	e.g. Switzerland:
Robbitemp 90020	Kent-Moore (Europe) AG
Air temperature measuring probe 90023	P. O. Box, CH-6340 Baar
(cable length 4.5 m)	Germany:
	Kalte-Fischer Postfach 2 66, Augsburger Str. 289 - 291 D-7000 Stuttgart 60

NOTE: Do not carry out the test in the workshop but on a vehicle which has cooled down after standing outside overnight. Interior compartment temperature > 20°C.

Test conditions

Outside temperature > + 10°C.
Driving time up until the start of measurements is approx. 10 minutes. If the outside temperatures are < 0°C, a longer measurement trip is required.
Windows and sliding roof closed.
Recirculated air button not pressed.
Do not allow engine to warm up to operating temperature.
Testing regulation
Attach measuring probe to sun visor and connect to measuring equipment. Switch on measuring equipment.

Fig 3: Locating Sun Visor
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Position air volume switch (S3) on stage "II".
Turn air distributor switch (28) to "4 o'clock position".
Position both temperature selectors (a, b) on center "white" area.
Recirculated air button (C) not pressed.
Start engine and drive off immediately (approx. 50 - 60 km/h).

Fig 4: Identifying Air Volume Switch, Distributor Switch And Air Button
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
After approx. 10 - 15 minutes, read off temperature on measuring equipment. Nominal value 22 ± 1°C. If the temperature is not attained, test electrical components of the automatic heater control (Diagnosis Manual - Climate Control, Volume 1).
Testing heat output
Place one measuring probe (arrows) in each of the left and right-hand defroster outlets. Engage both selectors on "RED".
Position air volume switch on stage "4" and air distributor switch at "12 o'clock position".
Allow engine to run at approx. 2000 rpm for 5 minutes.

Nominal value: > 55°C.

Fig 5: Testing Heat Output

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

NOTE: If the temperature is not attained, test function of the circulation pump. If in order, renew duo valve by experimentation, flush out cooling system if required. If this does not remedy the situation, replace heat exchanger.