I'm going to order and install the Climate Control Servo bypass kit for my 1980 300SD. The original servo is no longer working, neither is the auxiliary pump, and I'm tired of no heat control. Right now it's all heat all the time. The auxiliary pump has been broken for a lot longer than the servo, and I've been able to get adequate heat from the climate system. My question is, do I really need the auxiliary pump? I know it's recommended, but aux pump only really works during idle. Why can't I just put a U shaped pipe there in place of the auxiliary pump? My rationale for this idea is that I get enough heat now with the aux pump inoperative, so why do I need a new one? Thanks.