Also known as A/C control module. It resides strapped to the wheel bay liner on the passenger side. Lotus ID number B117M0038F which replaces A117M0038F. The ID on the part is YWB 100800 (TRW for Rover cars)
It consists of four relais switches: 1 for the A/C compressor magnet pulley, 3 for the cooling fans. It is controlled by the ECU and switches the fans simulataneously in either series (6V per fan) or parallel (12V per fan).
Series: when the engine coolant temperature measurement fails, when the A/C compressor starts (and trinary tells to??), when the first high temperature level of the coolant is reached (89 or 103 degrees??) – to be reviewed.
Parallel: when the second temperature level of the coolant is reached or when the heat soak pump is activated (??) – to be reviewed.
See picture below
Small plug #172 (controls)
pin 1 - 12V feed all fan RLY controls [purple]
pin 2 - ECU will ground this to close RLY3 [US blue/grey]
pin 3 - ECU will ground this to activate RLY1 and RLY2 (2 fans parallel/high) [UY blue/yellow]
pin 4 - 12V feed A/C RLY control [green]
pin 5 - ECU will ground this to activate A/C RLY [black blue]
pin 6 - blank
Large plug #173 (power)
pin 1 - blank
pin 2 - to A/C compressor, cabin fuse 4 first [R solid red]
pin 3 - to fan #2(and then ground) [light grey]
pin 4 - from RLY fan-1 to ground [??]
pin 5 - to fan #1 [PS ??]
pin 6 - from fan #1 [US blue/grey]
pin 7 - 12V feed from 20A fuse #14 [brown yellow]
pin 8 - 12V feed from 20A fuse #19 [NW brown white]
These data is 100% certain and i measured up the box in a stand alone situation as well.
(color codes, source Lotustalk)
B = Black
G = Green
K = Pink
LG = Light Green
N = Brown
O = Orange
P = Purple
R = Red
S = Grey / Slate
U = Blue
W = White
U = Blue
Y = Yellow
Connectors on the MFRU and the A/C module AFAIK are AMP Econoseal (J + III) family.
Small one: https://www.3waycomponents.co.uk/6-Way-AMP-Econoseal-III-070-Series-Female-Sealed-Socket-Wiring-Connector-Kit