Hi Scotty, firstly my wife and I LOVE your channel! We own a 2008 Mercury Grand Marquis Gs, odometer light went out but has around 150,000 miles. Bought used and heat has never worked; we changed thermostat, water pump, heater core, actuator for blend door, and blend door itself, flushed cooling system and inlet and outlet hoses are both hot at normal engine temp. Car has never ran hot, still no heat. Any advice would be great, thanks for all you do!!!
in other words, your vents are blowing air, but the air is ambient temperature? Does A/C blow cold?
A/C worked 3 years ago when i purchased car, no longer works, also replaced climate control module; air temperature is the same on any setting
Have you tried burping the air out of the system that could be trapped in the heater core?
i did after installing the new heater core. Used the old 'Rev up and hold at 2500-3000 rpm for about 30 secs, rinse repeat. No improvment
not sure about yours, but cars used to have burp valves
Just did a google search and called around a few shops, no one seems to be able to locate that valve on my model
You've replaced everything that could be wrong right down to the heater core, blend door actuator, and the blend door. You even replaced the water pump and EATC control head.
The vent selection (defrost, panel, floor) and "recirculate/fresh air" controls are manipulated by vacuum control motors.
But even if this was a "vacuum issue" you'd still have heat. You just wouldn't be able to control which vents it was coming out of.
The blend door actuator which you replaced is electrically controlled.
The system looks like this.
Air motor #1 controls the Panel Defrost Vents
Air Motor #14 controls the Floor Vents
Air Motor #9 controls Fresh Air/Recirculate
A/C/Heat Blend Door Actuator is electrically controlled and you've already replaced the actuator and the blend door.
The thing is, you say when you feel the heater core's inlet and outlet hoses they're both the same temperature. If they're the same "rigidity" when you squeeze them, it would seem that at least some (hot) coolant is moving through the heater core and you should feel at least some temperature difference (with the heater on, blower on low) coming out of the vents.
You don't.
So is the Blend Door Actuator getting power or is it stuck on the "A/C side"
First place to check is fuses #8 and #17 in your passenger compartment fuse box. Maybe even check them at their test tabs with a test light to make sure they're getting power. (they can't fry if they aren't getting any power)
If they're good you have to confirm the actuator is moving the blend door.
Could be a wiring/connector issue at the actuator or at the EATC control head. (Both were replaced but their connectors weren't)
I don't know if you can just pull out the glove box and reach up there or if you'll have to remove the passenger side airbag (easy) and get your fingers under the plastic duct to the vent to feel if the actuator is moving the blend door control rod.
Plastic Duct is removed in this picture
Thanks so much for the reply. The blend door is viewable through glove box with it unhinged, and it does open and close when changing modes with eatc controls. When I changed the eatc module, i noticed one of he pigtail connecters was melted (a little) so i spliced off another 3 plugs from salvage yard as well as 3 eatc units and switched out/tested all 3 wire clusters and eatc units. It's been a few months since but i did verify all fuses were good, I am planning on changing ALL fuses soon just to do it.
I have never heard of burping the system that way. If you don't have one of those burp funnel kits, park the car facing uphill, turn on heat setting to high and run it for a few minutes, then check fluid level in overflow tank.
Guess I was misinformed on the correct way to burp the system, will try this now, thank you so much for the quick response!
@doc Weather here hasn't let me dry burping the system until today, followed your advice on parking up hill and letting it run then check overflow levels. My car only has an overflow reserve tank, no cap on radiator itself, but opened that cap and kept an eye on it while car was oriented uphill and running. No air bubbles came from overflow nor did coolant levels dropped.
Did you turn the heat setting to high, thereby allowing coolant to circulate through the heater core?
doesn't the heat dial just control the blend door?
I did, left it up high the whole 45 mins or so. Weird thing is all I did was visually inspect under the hood and felt the hoses, touched nothing else, and for some reason the blower motor stopped working all together for like 3 mins, then i bumped the fusebox under the hood and it came back on. So I guess there's a loose connection somewhere in the wiring for the fuse box. Nothing else was affected by the "loose" issue though; lights didn't dim, radio played, windows, etc all other apparent elec system were fine, just the blower motor went out momentarily. Than wouldn't affect the heat situation, would it?
Could be corrosion on the fuse fitting. Usually, if a car is running hot, opening the heater valve and turning the fan on cools it down a little.
Definately could be corrosion, will have to have it looked at if I can't myself figure out why the fuse box has an intermittent connection, but it only does that if i wiggle the box. As Ive said the car has never ran hot, well once VERY briefly (because i used to drive a taurus that ran hot a lot so I've trained myself to always keep an eye on the temp) because of a blown fuse for the cooling fan