Originally posted by tkamiya
The fans are actually two staged. The low speed comes on when the a/c referegerant PRESSURE reaches the certain level. The high speed comes on when coolant temp reaches 107C in TEMPERATURE. The two fans are connected in PARELLEL. If one is working, the other one should be working as well.
P.s. The above figures are for E320. I don't have the numbers for E420.
tkamiya Thanks for the insight!
Sounds like my high speed fan may kick on
at approx. 107C as I have not seen the temp. climb beyond that. When temp has reached that point I am usuually in stop and go traffic and with the AC running. Just to confirm I will have to stop somewhere when it hits 107C and see if both are running!