Radiator Fan not turning on

[jdh-ram19]

2019 1500 Limited etourque

A little background.
Back in early November, I was pulling a trailer with about 8K of load. When I hit the side roads, I noticed my coolant temps running hot (230F) when I hit the stop lights, but it would cool down after I started moving.
I know that hauling will cause higher temps, and that is expected, but I did not expect the temps to rise while idle.
Got home and parked trailer, and popped hood and radiator fan was not engaged at 225F.
Took trailer off a couple of days later and have been watching temps closely for last 2 months.

Prior to November, when starting the truck, I would hear the radiator fan kick in high at startup. Then would settle down after a minute or so. That has not happened since Nov.
Radiator fan does not come on when running A/C (max or normal) when idleing.
If I get the oil temp up in the 220+ range, then when idleing, the coolant temp will climb up as well and the radiator fan will not kick in.

I was down in Austin over the summer with daily temps in the 105 range, and the truck would idle at 203-205 in traffic without issue.
Tried that in Atlanta back in early Dec and coolant was at 228F.
Went to FL over the holidays and while on interstate, coolant was running 197F. Once I idled, it shot up and no radiator fan.

Tried to take to the dealer, and the second I mentioned loaded trailer, they discounted the issue. Said they could not reproduce the temps. Took me 5 minutes after I picked up the truck to reproduce.
I have been able to manage the issue with start/stop while driving around town and can keep it under 215F, but looking for better solution

Trying to figure out what will trigger the fan. I am not sure it has come on since Nov. It does move freely when spinning by hand.
I tested the fuse side of the plug and I have 12V across the plug. The blue wire across ground is ~2.5v (I assume this is the low side of a relay)

I do remember seeing a document in my searches that said it was for the 5th gen and listed the criteria for engaging the fan. Have not been able to find it again.
It listed idle, under 38mph, max a/c and a few other conditions.

Any thoughts on how to test this fan?

 

[Scram1500]

Did you try a new fan relay or jumping the relay?

 

[SD Rebel]

I think the fan turns on at 230F, at least mine does.

I don't do a lot of towing, but I do a lot of idling in the heat on desert trails, and once my truck hit's 230, the fans turn on and bring it down to 220F. The operation range while moving without a load should be 200F - 220F. While at idle or slow traffic, 200F - 230F.

while under a heavy load up an incline for example, your coolant temps can reach 240-245F while oil temps up to 280F.

 

[HSKR R/T]

2019 1500 Limited etourque

A little background.
Back in early November, I was pulling a trailer with about 8K of load. When I hit the side roads, I noticed my coolant temps running hot (230F) when I hit the stop lights, but it would cool down after I started moving.
I know that hauling will cause higher temps, and that is expected, but I did not expect the temps to rise while idle.
Got home and parked trailer, and popped hood and radiator fan was not engaged at 225F.
Took trailer off a couple of days later and have been watching temps closely for last 2 months.

Prior to November, when starting the truck, I would hear the radiator fan kick in high at startup. Then would settle down after a minute or so. That has not happened since Nov.
Radiator fan does not come on when running A/C (max or normal) when idleing.
If I get the oil temp up in the 220+ range, then when idleing, the coolant temp will climb up as well and the radiator fan will not kick in.

I was down in Austin over the summer with daily temps in the 105 range, and the truck would idle at 203-205 in traffic without issue.
Tried that in Atlanta back in early Dec and coolant was at 228F.
Went to FL over the holidays and while on interstate, coolant was running 197F. Once I idled, it shot up and no radiator fan.

Tried to take to the dealer, and the second I mentioned loaded trailer, they discounted the issue. Said they could not reproduce the temps. Took me 5 minutes after I picked up the truck to reproduce.
I have been able to manage the issue with start/stop while driving around town and can keep it under 215F, but looking for better solution

Trying to figure out what will trigger the fan. I am not sure it has come on since Nov. It does move freely when spinning by hand.
I tested the fuse side of the plug and I have 12V across the plug. The blue wire across ground is ~2.5v (I assume this is the low side of a relay)

I do remember seeing a document in my searches that said it was for the 5th gen and listed the criteria for engaging the fan. Have not been able to find it again.
It listed idle, under 38mph, max a/c and a few other conditions.

Any thoughts on how to test this fan?

The fan won't turn on until 225-230. Sounds pretty normal for coolant temp ranges to me. Let it sit at idle, after warming up, and watch coolant temps. If they climb over 230 and don't start coming back down, then you have an issue.

Also, I'm sure when you were driving in Austin over the summer your A/C was on, keeping your coolant temps at the 203-205 mark

 

[jdh-ram19]

Should't turning on the A/C for the fan to turn on if the temp is in the 210 range? or will it just not kick in at all until 225+

 

[SD Rebel]

Should't turning on the A/C for the fan to turn on if the temp is in the 210 range? or will it just not kick in at all until 225+

That's an interesting question, I've seen people mention that before, I think HSKR R/T just mentions it as well in the post above yours, but I've been in the summer with my A/C blasting and I've seen my temps climb to 230F at hot idle and then immediately drop to 220F, indicating the fan just turned on.

In least with my 2019, the fan doesn't seem to turn on with the A/C, at least in that specific situation. It could be different in other situations like different cruising speeds.

 

[jdh-ram19]

That's an interesting question, I've seen people mention that before, I think HSKR R/T just mentions it as well in the post above yours, but I've been in the summer with my A/C blasting and I've seen my temps climb to 230F at hot idle and then immediately drop to 220F, indicating the fan just turned on.

In least with my 2019, the fan doesn't seem to turn on with the A/C, at least in that specific situation. It could be different in other situations like different cruising speeds.

Does your fan kick on at cold start? I would swear that mine did prior to November.

 

[SD Rebel]

Does your fan kick on at cold start? I would swear that mine did prior to November.

I have such a loud exhaust, I have no idea, but I'll try to see if it does on my next cold start.

 

[jdh-ram19]

Did you try a new fan relay or jumping the relay?

Is there a relay for the 5th gen? I have the full electric fan, and from what I have been able to tell, there is not a relay.
There is a 100A fuse on the side of the fuse block in the engine bay. Pulling the connector to the fan, I can test across the pos/neg and get ~12V, so I assume the fuse is good.

I have not been able to directly test the blue wire in the connector yet. My understanding is that the off/speed control for the fan.

 

[HSKR R/T]

Should't turning on the A/C for the fan to turn on if the temp is in the 210 range? or will it just not kick in at all until 225+

I think the A/C fan reads pressure sensors in the A/C and doesn't turn on unless it needs to. These vehicles are smarter than most people when it comes to stuff like that. The days of just turning the fan anytime the A/c switch is on are gone because it reduces the life of the fan motor

 

[Scram1500]

Is there a relay for the 5th gen? I have the full electric fan, and from what I have been able to tell, there is not a relay.
There is a 100A fuse on the side of the fuse block in the engine bay. Pulling the connector to the fan, I can test across the pos/neg and get ~12V, so I assume the fuse is good.

I have not been able to directly test the blue wire in the connector yet. My understanding is that the off/speed control for the fan.

You're correct, just looked at the relays, no fan