2000 Grand Marquis with 60k miles and a 4.6 engine. Heat stopped working the other day. Replaced thermostat. Still no heat. Flushed, flushed, backflushed system, new upper and lower hoses installed, fresh anti freeze. Still no heat. Heater core inlet hose gets hot, outlet hose does not. Everything points to a clogged heater core.

Any other possibilities or things I can do to fix?

If it is a heater core does replacement require completely removing the dash?

If dash removal is necessary, what's a repair cost guess? $800?

Thanks for any help.

 

Well, welcome to the forum.

Sorry, I can't help you as my Mercury is a 1992. My heater/AC controls are mechanical.

I'm not sure if the heater/AC controls on newer models is electronic. If so, it could be electrical.

You don't give much information to go by. How many miles? How many owners? Has car been in any accidents?

Anyway, in most cars - the heater core is in fact inside the dash. And the whole dash has to be taken out or apart. It is a lengthy and labor intensive job. And anyone who has taken apart a dash knows - there are many plastic clips and connectors. With some metal screws.

You could try a search online for instructions or a Chilton/Haynes book.

Good Luck.

 

i cheat the heater core out... i cut a hole in heater core box and install it that way... then after the new one is in place, i cover with wider piece of plastic to cover the hole... if your arms and stuff are skinny enough, i would unscrew the lower floor vents... i would see if the blend door is operating right in there not allowing the heat to be on like it should...

 

This is a 1-owner car (my mom's), 60,000 miles, never been in an accident.

Today when taking the car back to her house this morning I had heat. Sort of. If I set the automatic temp control to 85 degrees it warms the car. Of course it was around 45 degrees outside so I don't know how well that will work when it gets colder. What may be a clue on the problem is that when using the vent setting the heat is somewhat warm (certainly not 85 degrees) but the defrost setting blows much cooler air. The floor seems to be cooler too. The heater core inlet hose gets hot, the outlet does not. The coolant level is full. Not sure what all this may add up to.

 

best way i have cleaned out the heater core and check for flow is the following...

i unhook both heater core lines...
put a chunk of hose to one side to aim down or away from the car...
take another hose connected to water spicket of the house and turn it on with water goin in one side of the core and flowing out the piece of scrap hose...

if it is flowing right, i would get the car to operating temp and feel the vent system behind the glovebox to see if you can feel heat... if you feel heat thru the plastic but it dont blow out, you might have a blend door not working right

 

1. the thermostat may be locked up.
2. the heater in the dash may be burnt.
3. the relay may be bad.

 

Solved: Blocked heater core. Had the heater core professionally flushed, problem solved.