No Heat at idle

[Eightiesrock80]

i replaces the intake manifold and water pump and heater control valve and Themos stat I’m at a loss here I’m ready to get rid of this thing my daughter says Daddy why is it so cold because it’s a piece of $&@“ baby. LOL can anybody please help me. I fix everything but I can’t seem this. I’m pretty sure I got all the air out. Iv seen the air come out many times it seems to be done burping and gargling

 

[Bain64]

Have you checked if the heater core was clogged? Check inlet/outlet temps at the hoses, or you could do something similar to this at home core flush If you try the flush, what kind of flow rate do you get ?

 

[Eightiesrock80]

Yes I flushed it in reverse flushed it also.

 

[Bain64]

1. What about inlet/outlet temps of the hose just on engine side of the firewall? Does one hose feel hot and the other only warm?

2. What ambient temperature, and how long does it take to warm up?

3. Is the fresh air vent open or is it recirculating?

 

[Eightiesrock80]

When I’m driving down the road it’s super hot. Hoses are hott to the touch it warms up quickly but not the heat the gauge shows at half pretty quick to average. It doesn’t seem there’s anymore air in coolant. Were are the fresh air vents that recirculate. I didn’t know about this. Is it possible to heater control valve could be closing at idle at red lights because of a vacuum leak although I never feel anything with that vacuum line it seems to just always stay open

 

[Bain64]

The fresh air vents come in at the wiper cowl, directly behind the glove box.

Do you have the automatic HVAC controls? I've found it is always in fresh-air mode by default with the EATC. To get recirculate mode, and ultimately much better interior heat, press the forward heat button, or forward & floor heat, then press the recirculate button (picture of car with bent 180 degree arrow).

Moving from my Marquis to the Expedition, I thought I had a bad heater core; however I flushed it and found good flow. I found a couple things though, first is that the 5.4L coupled with a larger interior space greatly increased warmup time as composed to the 4.6 Marquis, but also that to get decent heat it must be in recirculate mode. I hope this helps.

 

[Eightiesrock80]

Yah it’s digital hvac system automatic. I noticed that when I opened the d-gasser cap on the over flow sometimes a ton of bubbles will come out and sometimes non. I felt the heater core hoses in and out and I noticed that one was hot and one wasn’t so hot the Inn was hot but the other wasn’t but when I start moving with the car the heat gets very very hot. I think I need to do another reverse flush on the heater core

 

[Adieu]

I think thats just how it works, idling to operating temps takes forever.....give her a couple long revs in park and it'll heat up much faster

 

[Eightiesrock80]

What does this vacuum looking line goto I see nothing it Just sticks straight up

 

[Eightiesrock80]

I circled it here the end is cracked off and goes to nothing

 

[Eightiesrock80]

The out heatercore hose is pretty cool compared to the in its hot at idle but that can change could be air or could be clogged I’m looseing my mind lol

 

[Jarheadmatt]

is the heater valve vacuum operated? I know you said the HVAC system is auto, but if the valve is vacuum operated you may have a vac issue. Another thing could be the blend door motor.

 

[Eightiesrock80]

When I make the heat go from hot to cold when the heat is actually working it goes back-and-forth so I believe the blend door is OK

 

[Eightiesrock80]

The vacuum line for the heater control valve doesn’t seem to do anything the heater control valve seems to always be open I did just noticed that one heater hose to the heater core is sometimes cold in the other one is hot so I’m thinking I need to unclog the heater core

 

[Eightiesrock80]

It’s so weird though Out of know where the heat will work good but When I stop it still will not be as hot but warm

 

[99WhiteC5Coupe]

The vacuum line for the heater control valve doesn’t seem to do anything the heater control valve seems to always be open I did just noticed that one heater hose to the heater core is sometimes cold in the other one is hot so I’m thinking I need to unclog the heater core

Years ago I had problems with low heat on a Chevrolet I owned, that had a vacuum operated heater control valve.

The valve seemed to work - the lever would open and close. My father suggested I remove the valve and inspect the inside. I did and found that the “flap” that would block the coolant flow inside the valve was loose and not moving to the full-open position, although the vacuum operated lever would move back and forth. I replaced the valve and that cured my low heat issue.

If your valve is stuck open, it may have a partial blockage inside the valve - which is overcome when you increase the engine’s speed.

You may want to remove and inspect the valve. Good luck.

 

[Jarheadmatt]

after warm... manually operate the heater valve and see if the hose temps change. could be a signal issue or the valve itself

 

[Eightiesrock80]

Thank you guys I will be checking these in getting back to you thank you so much