Hello everyone just wanting to reach out to you guys to see what could possibly be going on with my 2018 f150 3.5. Noticed the other day that my truck took forever to supply me with warm air even though I have been driving for about 5 minutes and my truck was already warm. It came out cold and after about 3 minutes of continuous cold air it got hot and then stayed hot? What could be causing the delay in the heat getting out of the system? Also idk if this has anything to do with it but I have noticed that my fan has constantly been on high idle even while it's been sitting for about 5 or so minutes? I haven't noticed any coolant leaks anywhere and I don't show any signs of one either?

 

First thing I’d check is your anti-freeze level. If that’s ok I’d replace your thermostat which is an easy job. I say that because you fan shouldn’t be required to be running on high idling this time of year unless you’re in the Congo! Doesn’t sound like a blend door issue but there’s plenty of post on how to check if that’s the issue. Good luck....

 

Is this truck new to you? If not has any work been done on it recently? Any AC work? Water pump? Thermostat? If you replace the thermostat make sure you use a Ford and its in the correct orientation.

 

Almost always thermostat stuck open.

 

Have you checked to see if the heat is moving on the passenger side? Could be a bad blend door actuator (search YouTube). But if you are getting no heat, then yeah probably stuck thermostat.

 

I check my anti freeze level and it was low and had to add about a gallon to the system. Yes I did check at cold and hot and it was very low than the minimum level on the tank. It still is doing high idle fan though so might be a thermostat issue.

I'm going to be getting the cam phasers changed out in the coming weeks and I was advised to go ahead and change the water pump and thermostat along with this job since they're already going to be there and taking that stuff off anyways.

 

Bought the truck brand new with 2 miles on it in 2018 and the only work that has been done has been all warranty work

 

Yeah the air was running full speed on both sides of the truck but just pushing cold air around for a few minutes then heat comes back.

I was about a gallon low on coolant and the heat seems to now be there when it's supposed to be now. But my high idle fan is still on so leads me to believe the thermostat might be bad

 

Coolant a gallon low? You have a major issue. There should be no need to add coolant.

 

There's a slight leak I found this morning so depending on how long it has started to leak would dictate loosing almost a gallon. I checked the oil and theres no signs of it in my oil and was confirmed by the mechanic shop. Ill be doing the cam phaser fix here in the coming weeks and will be purchasing all new hoses and connectors. It's also still at the same level as I filled it up to yesterday.