Automotive Air Conditioning Information Forum

I was hoping someone could point me in the right direction to learn more about this subject. I have a '71 Pontiac station wagon (original 455 slightly bored when rebuilt) that I will be retaining the mechanical cooling fan. It overheats when the A/C is on when idling, so I want to add an electric pusher fan in front of the condenser (This system has a POA valve and does not "cycle" as many systems do). I don't want to wire this fan to just come on whenever the compressor is on. I want this fan to only run when the A/C pressures get too high, so it will kick on when pressure go high when idling but will kick off if I'm on the road and getting plenty of airflow (also, in the winter when I'm running defrost I don't want to pusher fan coming on).



I have heard that a trinary switch may be a good way to do this, but I need to learn more about how this works, where to place it, or what better options may be available to do what I want. For example, maybe a binary switch would be all I need since I will still have the regular mechanical cooling fan and all I need is an simple on and off for the pusher when the pressures are too high (no high and low speeds needed).



Thanks,

Brandon

First, a pusher fan will not move as much air as a puller fan. Check to see how much clearance you have between the radiator and mechanical fan. The newer fans have become much slimmer and will probably fit.

Next, you either will have to have your system heat sensitive and rig up a sensor on the condenser so that if it gets too hot the fan will run, or rig up a pressure system for the same. Using a pressure switch with a puller fan is the best option.

Look up the circuit a Dodge Sprinter 2006 and see how they have it set up. They have exactly what you want.