I have a 350 paired to a 700r4 with a 2000 stall converter with 2.73 highway gears and working AC. I have the furd taurus fan installed with it always on high, the rad is a brass "the radiator factory" stock looking unit which looks new inside, in front of that is a parallel flow condensor for the AC and then I have a small auxiliary cooler for the transmission in front of that (which im almost convinced doesn't even do anything because the tubes are hot as hell but the fins arent)

For context the car will cool itself off just fine without the AC on, will rarely get above 195 (that's the t-stat I put in), occasionally I notice it get slightly above the first dot on the gauge but that's only in stop and go traffic and will generally come back down. As soon as I turn on the AC I start to notice the temps start slowly creeping up towards 200 in stop and go, 220 being the absolute worst case scenario, from what I understand this is fine but prior to my recent tranny install it has never done this, it's always stayed at 195 during the summer even with the AC on from what I remember with the old trans that had a very tight converter. In order to get the car to cool down to a reasonable level I have to get the car fast enough to lockup in 4th gear, then it will cool itself down like it's nobodys business and stay at 180-195 even with the AC on. The issue I have is when I'm at idle in park, the temp will stay at 200-210 and not go lower even if I turn off the AC, this is not good for many reasons, the car should be able to cool itself down at idle just fine with the taurus fan and the AC being off, my working theory is that the trans is running at a significantly higher temperature due to the higher stall and tall *** gears and dumping that into the radiator and for whatever reason the trans cannot get rid of that high temp effectively, probably because the stock radiator was never designed to handle a stall speed converter and the auxiliary cooler is doing jack. I'm not sure though, theres no temp gauge, im only going off the dipstick which feels scolding hot and I can see a couple of bubbles on it. I have a new auxiliary cooler coming in tomorrow so hopefully it's one less variable. It's just really weird that even when you turn off the ac it will never back itself down from 200-210 at idle, what could the cause be?

 

The converter is only going to build heat when it is under load. At idle in Park/Neutral or in lockup the converter builds little if any heat. Once the engine has heat in it at idle it is hard to cool it back down with a small single electric fan.

 

All the other information was fine, but the answer to your problem lies in the two quoted sentences. You have insufficient airflow at idle. The Taurus fan might be fine, check to make sure air isn't leaking around it like no shroud or something. Focus on that. Everything else is just noise.

 

when I redid the tranny cooler and lines to flow correctly (they were backwards) and put a much better cooler in, it made a big difference as tranny temps are waaay better than before. This is where my water temp gauge sits at now, it used to sit above the first peg. So whatever I did made a huge difference, if I have the AC on it stays on the first peg and doesn't move, when I turn it off it goes back under the peg, I'm happy with these results so far. I'll test it more as it gets hotter out but now the tranny is one less variable. Even if it was getting to 220 with AC on it's normal for these cars, I just want it to cool itself off at idle when I turn the AC off which it seems to be doing now. If it continues to have issues ill look at the airflow at idle

 

If there is actually any improvement by swapping out the cooler and swapping lines then you have more heat retained in your transmission now. Not sure where your tranny temp sender is located but the heat that was overloading your cooling system went somewhere. It is either being kept in your transmission now or you have misinterpreted your results. Simple physics. The heat went somewhere, and if you didn't improve airflow to get rid of it then it is still there somewhere.
But glad you are happy with what you have now. Drive it and see what happens.

 

I was worried the heat is being kept in the transmission so I put a temp gauge in the pan that tells me what it's running at and the temps are 150-170 consistent. In reality this whole time the electric motor in the taurus fan was on it's way out pulling way less air than it should and quit while I was on a 200 mile road trip, I had to drive for 20 miles on just the air dam to get this thing to an auto parts store where I put a fan in. I have a new one coming in a couple of days, hopefully this info will help someone in the future.

I used a dorman taurus fan and it seemed to have pulled more amps than it should've when running but I shrugged it off, lasted 8 months that way.

 

I had the same thing happen with my old Taurus fan. Thought it was good but it was well on its way out and not pulling nearly as much air as it should've been. I run a brushless fan now out've a C7 Vette. Lot less amps and tons of CFM.