Hi all. Looking for some help or a point in the right direction with an issue I'm having. On a cold start, warm start (any kind of start) the radiator cooling fan turns on immediately and does not turn off until the vehicle is shut off. It doesn't actuate if the key is in the run position without starting.

I only noticed this because the van never reaches operating temp until it's driven. It takes forever to warm up if left to idle (30 minutes plus.) The heat is warm at idle but if I give it throttle or if I'm driving, the heat is very warm. I changed coolant, thermostat, and bled the system and the issue still persists. That's when I noticed the fan always running (on normal speed.) No warning lights or anything.

Side note in case this may be related. I did a rear a/c delete because of leaking/rotting lines and capped off the lines up front (about 10 months ago.) Recharged the system and it blows cold and holds pressure. Also, under acceleration the air blowing from vents switches to defrost. It will revert to normal when gas pedal is eased off/let go. I understand this is a vacuum leak and did the vacuum reservoir reroute and check valve replacement but the problem still persists.

Apologize for the length. Any input is appreciated.

 

Check CHT sensor since it controls the radiator fan. What you can do is to just remove the electrical connector and use contact cleaner to clean. If if doesn't help check the CHT.pdf below.
You said it takes forever to warm up, how do you know your temperature gauge is providing the correct temperature? You can do the same cleaning as CHT, just the electrical connector (both ends) to your ECT (for gauge). ECT never breaks, 99% of the time it's the bad wire connection causing the false reading.
I tried to attach a location diagram on CHT and ECT but somehow I can't upload it, I will try again later.
You said you replaced the tstat, which brand which model? Got any CEL after you replaced the tstat?
You might want to bench test the check valve itself to ensure it's functioning (directional) if you can't locate the vacuum leak.

 

I tried it on different computer and I still can't upload any image (jpg, png). I saved it in PDF so check Location.pdf below.
Locate C172 (CHT) and C137 (ECT for gauge).
Finally managed to upload the jpg below, so you can ignore the Location.pdf since it's the same thing.

 

Thank you for the files. I cleaned the connections on both sensors but no change. It only takes a while to warm up if started and left to idle. If driven it will warm up normally. I replaced the thermostat with a motorcraft rt-1254. No CEL was present or is currently present. I'm a assuming that if the CHT sensor was bad the CEL would be illuminated. I'll dig a little deeper tomorrow and see what I find.

 

Above diagram shows the OE spec (176 to 183 degree)
The tstat choices out there are in 160 to 196 range. I asked you which tstat just want to make sure your new and the old tstat are not colder than OE spec. If the temperature difference is 10 or higher on old and new tstat, that could trigger the check engine light and a CEL reset should clear that permanently. Your Motorcraft RT1254 is 190, so your 190 tstat opens a little late. When it opens late your engine should reach operating temperature sooner than OE spec. Not that picking Motorcraft RT1254 is out of OE spec, it depends on the location and driving style. It's better to open little late than too soon. For those who don't like warm up their cars in the morning (especially in cold weather location), they should get the highest temp (196) and never go lower than OE spec.
So your tstat, if it opens at 190 (fully open add another 20 (190+20=210)), and your temp gauge doesn't move upward at all in 10 minutes, then something is wrong. Check Tstat-Test.pdf below if needed. When your van reaches operating temperature during driving, it really doesn't matter as it will likely stay at full open anyway.
If you have a scan tool able to do live data, bidirectional and active test, you can turn on/off the tstat and radiator fan by hand with just a few clicks, or monitor at what temperature it turns on. It might save you more time that way.