F-150 thermostat?

[Angry Perch]

2012 F-150
5.0 liter

With heat on hi, vents blow cool at idle, and warm when I bring the RPMs up over 1000 or so.
Thermostat?

[Buckmark]

Could be, could also be low coolant level, poor flow through the heater core etc.
That vehicle may throw a fault code of P0128 coolant temp.
Check heater hoses temp in and out with a heat gun or your hand, if you have access to a scanner check engine coolant temp per scanner and proceed from there.

[jackelope]

2012 F-150
5.0 liter

With heat on hi, vents blow cool at idle, and warm when I bring the RPMs up over 1000 or so.
Thermostat?

On both ends of the dash?

[Angry Perch]

2012 F-150
5.0 liter

With heat on hi, vents blow cool at idle, and warm when I bring the RPMs up over 1000 or so.
Thermostat?

On both ends of the dash?

Yes I think so.

[CP]

I'd just change it.  Cheap part and an easy job.

[skeeter 20i]

can you change the temperature at all by just adjusting the blend knob?  If not then I might suspect the blend door inside the dash. 

[Woodchuck]

can you change the temperature at all by just adjusting the blend knob?  If not then I might suspect the blend door inside the dash.

A far more common issue than thermostat on that truck. 

[Fl0und3rz]

Are they still vacuum actuated in that year?  Vacuum leak?

[Woodchuck]

Are they still vacuum actuated in that year?  Vacuum leak?

Electric, dual zone trucks are even more fun.

[jackelope]

can you change the temperature at all by just adjusting the blend knob?  If not then I might suspect the blend door inside the dash. 

90% of the time it's one side or the other that doesn't work.  That's why I asked. Temperature blend door actuators go bad all the time.

Is the engine temperature behaving normally?

[Buckmark]

can you change the temperature at all by just adjusting the blend knob?  If not then I might suspect the blend door inside the dash. 

90% of the time it's one side or the other that doesn't work.  That's why I asked. Temperature blend door actuators go bad all the time.

Is the engine temperature behaving normally?

Thats why i said to start with some simple diagnostics
1) Engine coolant temp per pcm - if it is normal say 195 good, (easy check) next step
2) coolant hoses in and out of core, hot in and cold out? restriction in core, hot in and still hottish or very warm out, core is good for flow (easy check) next step
3) getting a little harder as now you are looking at possible air inlet door and or actuator, the blend doors on the vehicle show a right and left, so if it is even on both sides may then be inlet problem, etc etc....

Start at the basics, coolant temp, coolant flow then make it harder 

[Bean Counter]

I'd just change it.  Cheap part and an easy job.

 

[Angry Perch]

Thanks for all the input. i'll start looking into it tonight. I can sit at idle, and the vent blows cold. I rev to 1000+ RPM, and it goes warm. back to idle, and blows cool again. Temperature adjustment (blend) works as it should as long as RPMs are up.

[jackelope]

I'd just change it.  Cheap part and an easy job.

 

Sure. Just change it. Spend your 2 hours and your money and when it's not fixed, throw some more parts at it that don't fix it.
The blend door actuator actually takes less time than the thermostat to change and the part is likely cheaper. Just FYI.

[jackelope]

I'd just change it.  Cheap part and an easy job.

 

Sure. Just change it. Spend your 2 hours and your money and when it's not fixed, throw some more parts at it that don't fix it.
The blend door actuator actually takes less time than the thermostat to change and the part is likely cheaper. Just FYI.

Nevermind. The t-stat pays 1.1 and the right side actuator that goes bad commonly pays 1.4 hours.
But...why diagnose anything when you can just throw parts at stuff.

[Buckmark]

I'd just change it.  Cheap part and an easy job.

 

Sure. Just change it. Spend your 2 hours and your money and when it's not fixed, throw some more parts at it that don't fix it.
The blend door actuator actually takes less time than the thermostat to change and the part is likely cheaper. Just FYI.

Nevermind. The t-stat pays 1.1 and the right side actuator that goes bad commonly pays 1.4 hours.
But...why diagnose anything when you can just throw parts at stuff.

Yeah but by the time you get coolant all over your garage/driveway, run to the parts store because you forgot to get the correct coolant, replace the stat, refill/burp the system and clean up the mess, you will be past the blend door time.....

[jackelope]

I'd just change it.  Cheap part and an easy job.

 

Sure. Just change it. Spend your 2 hours and your money and when it's not fixed, throw some more parts at it that don't fix it.
The blend door actuator actually takes less time than the thermostat to change and the part is likely cheaper. Just FYI.

Nevermind. The t-stat pays 1.1 and the right side actuator that goes bad commonly pays 1.4 hours.
But...why diagnose anything when you can just throw parts at stuff.

Yeah but by the time you get coolant all over your garage/driveway, run to the parts store because you forgot to get the correct coolant, replace the stat, refill/burp the system and clean up the mess, you will be past the blend door time.....

Didn't think about the correct coolant debauchery.

[Bofire]

and Beancounter is such a wizard with cars. what kinda oil???
Carl

[timberghost72]

An ECM controlled blend door issue if cold at idle and warm when idle is raised >1000? Probably not. Check the basics first. 

[jackelope]

An ECM controlled blend door issue if cold at idle and warm when idle is raised >1000? Probably not. Check the basics first. 

Is engine temperature ok?

[timberghost72]

An ECM controlled blend door issue if cold at idle and warm when idle is raised >1000? Probably not. Check the basics first. 

Is engine temperature ok?

  And check coolant level. Then what temp does the t-stat open at.

[coachcw]

Verify coolant level , turn and turn fan off for a couple minutes . rev engine to 1500 rpm and hold . turn fan on max and check for heat (good heat ) if heat blows hot for ten to twenty seconds then cools off look for a plugged heater core .

[CP]

I changed the T-stat on my 4.6L F150 not long ago.  Less than $15 and takes about 15 minutes.

Amazon Prime one day delivery on the parts, make sure it comes with the O ring.

Drain out about a gallon or so of coolant into a clean bucket.  The t-stat is at the top of the engine so you don’t need to drain much.
Remove the t stat housing (2 bolts, you can leave the hose on).  Toss the old t-stat and O ring, clean the surfaces, put in the new parts and reassemble.
Put the coolant that you drained out back in.

Done.

I have an Edge – programmer reader.  One of the supported parameters is engine coolant temperature.  Very useful to monitor the temp real time as you drive if you have such a question.  Well worth the investment if you keep your vehicle well beyond warranty and you do your own maintenance.

[Woodchuck]

On a '12 5.0 truck the thermostat in on the bottom. 

[CP]

On a '12 5.0 truck the thermostat in on the bottom. 

Well, that's unfortunate.   

[jackelope]

I guess I might check for fault codes before I did anything. T-stat and the actuators will set codes. We can all sit here and desk jockey this thing, but the OP hasn't answered any of the important questions to properly formulate an (in) accurate internet forum diagnosis.

I changed the T-stat on my 4.6L F150 not long ago.  Less than $15 and takes about 15 minutes.

Amazon Prime one day delivery on the parts, make sure it comes with the O ring.

Drain out about a gallon or so of coolant into a clean bucket.  The t-stat is at the top of the engine so you don’t need to drain much.
Remove the t stat housing (2 bolts, you can leave the hose on).  Toss the old t-stat and O ring, clean the surfaces, put in the new parts and reassemble.
Put the coolant that you drained out back in.

Done.

I have an Edge – programmer reader.  One of the supported parameters is engine coolant temperature.  Very useful to monitor the temp real time as you drive if you have such a question.  Well worth the investment if you keep your vehicle well beyond warranty and you do your own maintenance.

Solid instruction for a 4.6
He has a 5.0

[Angry Perch]

Got home last night and could smell coolant when I got out. Same this morning. Pouring rain, dark and no shop to work in doesn't make for a great combination for diagnosing a coolant leak. Heading over the mountains with the family Friday, so dropping it of at Evergreen Ford in the AM.

[Fl0und3rz]

Take it to @Coach shop, if he can fit you in and you can get it there.  I would tow (have towed) my vehicle there just to get it done right.

[jackelope]

Got home last night and could smell coolant when I got out. Same this morning. Pouring rain, dark and no shop to work in doesn't make for a great combination for diagnosing a coolant leak. Heading over the mountains with the family Friday, so dropping it of at Evergreen Ford in the AM.

Bring it to me. I'll take care of it for you. Evergreen sucks. PM if you want.
How many miles on it?

[Fl0und3rz]

That, too.

[jackelope]

That, too.

Either way. Coach does great work, it's just a ways from Issaquah. If the miles are right, there's potential for powertrain warranty with a coolant leak.
Depends what it is and how many miles.

[Angry Perch]

63K

[jackelope]

63K

OK, so you're out of powertrain warranty. If there is a leak, the low coolant will likely be the reason for the lack of heat.

[Angry Perch]

Turned out to be the T connector on the hose. Part is back ordered.

[coachcw]

pretty good chance napa will have it

[jackelope]

pretty good chance napa will have it

Backorder through Ford with no ETA. It's great(sarcasm). Had one in the shop today with the same problem. No parts. Fortunately it was a very small leak. Topped it off and sent the guy down the road with a half gallon of coolant.

[Buckmark]

If it is a T that has hose with quick connects on them you could cut off the quick connects and get a T from NAPA to replace it?
Not the bet solution but a solution possibly
*
I would be interested in what a Dealer would say if someone blew a head gasket etc from low coolant if they coudl only top it off and send them away with no ETA on the proper part.

[jackelope]

If it is a T that has hose with quick connects on them you could cut off the quick connects and get a T from NAPA to replace it?
Not the bet solution but a solution possibly
*
I would be interested in what a Dealer would say if someone blew a head gasket etc from low coolant if they coudl only top it off and send them away with no ETA on the proper part.

On a truck with 130k miles on it, we say... keep an eye on the coolant level.... here's a little extra to get you by. As I said, this particular truck I had today had a tiny leak. Went from the full line in the degas bottle 2 weeks ago to maybe an inch below it today...~500 miles.
What would an independent shop say if you couldn't get the correct part? The shop is not responsible for the owner's vehicle. If the guy overheats it because he ran it out of coolant knowing he had a leak and drove it till it stopped, that's not our problem.