2006 4.6 Roaring fan, occasional overheat

[ThunderbirdSport]

Occasionally I still have the temp gauge get hot, and the fan roars, and on the highway, when downshifting to pass, there's a squeal, until the trans shifts back into overdrive.

It only does it when the engine is up to temp and the AC is on. Oddly enough, if I keep the AC on the coldest setting (60*) it doesn't do it nearly as often. Put it up to 65*, 70* etc and it it happens almost instantly.

New fan clutch, t-stat, water pump, new cylinder head temp sensor, newer radiator, I also took the rad out last summer and blew it out, it was clean.

I have a new temp sensor to go in wednesday, and I'll take a look at the belt too.

This is on the 4.6, by the way. Is there also a fan controller or is that ran through the PCM as well?

Hence the reason to replace the temp sensor again....if it's out of spec....

I also checked all the wiring for fraying, broken insulation...couldn't see anything that looked bad, also, sometimes idling with AC on the gauge will go hot and the air will not blow nearly as cold. This is all intermittent. The only thing that's constant is when I bump the cabin temp up over 60* (auto climate control, and also rear heat/air) will definitely make the temp gauge go up. It doesn't seem as if the engine is actually overheating, there's no coolant loss, or anything that would indicate an actual overheating. I do know I need to IR temp scan the engine and hoses to verify.

Just wondering what else I could look into. I hate throwing parts at a problem, but literally have no clue what else to look at..

To reiterate;
NEW:
fan clutch
water pump
T-stat
cyl head temp sensor (under the intake)

I know I could have gotten a bad t stat, but I think it's would be a constant issue if so, rather than intermittent, no?

I also read online where someone said I had to get the fan clutch programmed after replacement...anyone ever heard of that?

Thanks!

 

[94Eddie]

The one thing you did not mention replacing is the radiator cap. Might be worth buying one as a Hail Mary.

 

[LorenzoGarbanzo]

How's your belt and belt tension looking? The squealing on downshifts you report makes me wonder if it isn't turning the fan & water pump well enough. However, you'd most likely have weak power steering & charging issues also reported.

 

[ThunderbirdSport]

Yeah, no, there's no charging or power steering issues. My phone's camera is bad, but as soon as I get replacement, I intend to take a short video to show just exactly what it does.

 

[michael loibl]

Air trapped in the cooling system?

 

[ThunderbirdSport]

Air trapped in the cooling system?

I've put it on an incline and let it run with the cap off for about an hour 2 or 3 times..

 

[BKennedy]

Replace the belt and the belt tensioner.

 

[Mitchs07explorer]

You mentioned you changed out the cylinder head temp sensor, is that the same as a coolant temperature sensor? I know on my V6 the temp sensor is located on top of the thermostat housing and can cause the issues you’ve described.