GF83.40-D-2190H | Expansion valve, component description | 12.5.06 |
MODEL 906.111 /113 /131 /133 /135 /153 /155 /211 /213 /231 /233 /235 /253 /255 /611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735 except CODE (HH9) Regulated air conditioning (Tempmatic)
D83.40-1107-08
25 Front expansion valve
Location
The front expansion valve is located in the feed and return line of the air conditioning on the firewall in the engine compartment on the right next to the windshield wiper motor (M6/1).
Task
The front expansion valve regulates the flow of refrigerant into the front evaporator as a function of the low pressure (gaseous) and the temperature at the outlet of the front evaporator.
Design and function
26 Diaphragm
27 Aluminum housing
28 Control valve
29 Ball
30 Spring
N83.40-2039-03
When the refrigerant compressor (A9) is switched on, there is a decrease in suction pressure in the line leading from the front evaporator to the refrigerant compressor. This causes the diaphragm to bend downward. The control valve follows the movement of the diaphragm and presses the ball out of its seat and against the spring. This causes more refrigerant to flow through the front expansion valve into the front evaporator. More refrigerant evaporates in the evaporator and the suction pressure in the line leading from the front evaporator to the refrigerant compressor is increased. This causes the diaphragm to bend upward. The control valve follows the movement of the diaphragm and the spring force of the spring presses the ball onto its seat. This causes less refrigerant to flow through the front expansion valve into the front evaporator. Less refrigerant evaporates in the evaporator and the suction pressure in the line leading from the front evaporator to the refrigerant compressor is decreased again.
The flow of refrigerant into the front evaporator is regulated by the front expansion valve. The movement of the diaphragm depends on both the suction pressure and the temperature at the front evaporator outlet. Only as much refrigerant flows as can be optimally evaporated.