Service Information: Maintenance and fault diagnosis of air conditioning system

Attention in maintenance and troubleshooting diagnostics in the air-conditioning system

This Service Information has the purpose of disclosing the attention to maintenance and troubleshooting diagnostics in the air-conditioning on Mercedes-Benz do Brasil trucks.

Before staring the vehicle's operation verify that all necessary safety measures are fulfilled.

Observe the torque recommended when performing maintenance.

B83.00-0021-01

B83.00-0022-01

Procedures for recycling the air-conditioning system

Never perform the gas charge only through the low line (suction).

A - Low pressure line

B - High pressure line

C - Gas

D - Oil

E - The oil in the compressor is expelled

F - The oil in the compressor is kept

B83.00-0023-01

B83.00-0024-01

Always charge the refrigerant gas using a graded bottle, electronic scale or recycling equipment. Never charge refrigerant gas monitoring the charge only by the pressure gauges.

A - Low pressure line

B - High pressure line

G - Graded bottle

H - Electronic scale

J - Recycling

B83.00-0025-01

Load the system with lubricant oil recommended by the air-conditioner manufacturer

A - Low pressure line

B - High pressure line

 Collect the gas in the air-conditioner system.

 Check the quantity removed.

 Verify if there is any damaged component in the air-conditioning system. If there is a damage, perform the necessary maintenance.

 Do the leaking/vacuum test. If the leakage does happen, stop it.

 Fill it with lubricant oil (quantity removed by the recycling plus the quantity defined in the refilling table below).

Components

Vaporizer

Condenser

Dehydrator filter

Draining hose

Suction hose (compressor inlet)

High pressure hose (compressor outlet)

Other hoses

Oil quantity (ND OIL 8) to be added to the air-conditioning system

Add 50 ml

Add 50 ml

Add 30 ml

Add 20 ml

Add 15 ml

Add 10 ml

Add 10 ml

Total 185 ml

Whenever the gas charge collection and/or air-conditioning system component exchanges happen, refill the system with lubricant oil collected by the recycling plus the quantity specified for every component. Observe the table above .

In the compressor substitution do not add oil to the system

Before substituting the compressor, ensure that there is a total oil removal from the system, since the compressor is supplied with the total specified oil, i.e. 185 ml.

If the oil refilling is not performed according to specification in the table above, because of disassembly of any components, the compressor is going to work with inappropriate oil volume, causing the internal components to wear out and consequently locking the compressor.

B83.00-0026-01

Observe the gas quantity to be filled in the system, according to what is informed in the TAG, posted in the cabin front part; visible when the front cage is open, near the air-conditioning system pipes:

Specified gas charge (A), and tolerance (example on the picture shown, vehicle Axor C).

The vehicles Accelo and Atrondo not have the tag (on the side) referringto the air-conditioner.Look at the table below

Gas charge table by vehicle:

Vehicle

ACCELO

ATRON (FPN)

ATEGO

AXOR - C

AXOR - R

ACTROS (without SKA/night or parking air-conditioner)

ACTROS (with SKA - code H09)

Gas charge

425 g +/- 25 g

425 g + 25 g

550 g + 50 g

1100 g + 50 g

1200 g + 50 g

1100 g + 50 g

1600 g + 50 g

B83.00-0027-01

B83.00-0028-01

Example of preparation for the air-conditioning system maintenance, vehicle AXOR

 Tilt the front cage and verify visually if there are not any leaks in the high pressure pipes (B) (red color) and low pressure (blue color) in the air-conditioning system.

 Sterilize and check the collection flask (C) weight for the compressor lubricant oil (29,8 grams).

 Install the high and low pressure hoses in the recycling.

B83.00-0031-10

Collection of gas and lubricant oil in the compressor

 Gas quantity recovered by the recycler = 960 g.

 Oil quantity collected by the recycler = 46 cc or 45.4 g. (The equipment can not collect 100% of system oil).

 Collected and weighed oil, not considering the flask weight (29.8 grams).

B83.00-0030-12

Preparation to refill the oil and gas in the air-conditioning system

 Do the vehicle test for 10 minutes.

 After the test, wait for 20 minutes as you check if any alteration in the equipment vacuum value happens (E).

 If there is no alteration in the vacuum value, it means that the system does not have leaks.

 Refill the gas quantity specified for the vehicle and the same collected oil quantity in the system, because it did not show leaks or component failures.

 There can not be any variations during the vacuum test (E). (ALWAYS WAIT 20 MINUTES IN THE VACUUM TEST)