97 Mark -- Can't Turn Heater Off -- help!

[lamarkviii]

I have a 97 Mark VIII that had a brand-new heater core put into it when I bought it from a small after-market dealer in 2005. Never had any heater issues until this week.

It seemed like the air wasn't getting very warm, so yesterday morning, I notched the setting up from 72 to 78 to see if it got warmer, fearing perhaps another core failure (but the air did get warmer this time). Parked, went to work, came out and started up my car. The heater was on, but obviously blowing cold air since it had been sitting all day, so I turned it off... and my car suddenly sounded like someone was trying to murder it (literally the worst combination of grinding/squealing I've ever heard).

I turned the heater back on as it was the only thing I knew for sure had changed since I got in the car. Noise stopped. Car is running fine so long as the heater is on, but every time I try and turn it off, that griding/squealing noise starts up.) The car doesn't run any differently that I can tell while the noise is happening, it just sounds godawful.

I am fortunate to have a great Lincoln dealer nearby that has been awesome with my service since I got the car, but I probably can't get to them before early next week, so my main questions are:

1) has this happened to anyone else?

2) If you have any theories on what it is, will I damage my car by continuing to drive it?

I'm pretty sure whatever it is must be the only part in this car that hasn't been replaced... so that'll be just my luck, whatever it is, lol. But anyway, any thoughts or theories would be helpful to this rain-soaked Mark owner.

Thanks.

lamarkviii

 

[97markviii]

Not completely sure here, but recently I had to replace my turpentine belt because of the same sounding grinding/squealing issues, so maybe you need to replace your AC Core...but this is just a guess...

 

[lamarkviii]

A little more info -- I'm not sure if this spurs any additional ideas, but I've also had a few oddities with my messages in the car. My car will give me a "driver's door ajar" message when my door is securely closed and locked, and sometimes it even unlocks my door and refuses to lock it again. And I seem to get a lot of flashes of the memory recall turning off message kind of out of nowhere.

I'm pretty resolved to having to take her into service tomorrow, but just still curious if anyone's ever had a similar problem.

lamarkviii

 

[chicken]

if the blower is running with the heater control off then its most likely your blower motor controller (a fancy blower motor resistor) kinda pricey too, the door ajar is the door switch, its in the latch just spray some wd40 in the latch facing downward and slam the door a few times and the light should go off, if not most likely its the switch. for your noise, a little better description would help, is the noise under the hood/inside the car. if under hood look for something that is doing something along with the noise (example, only have noise when ac clutch disengages)

 

[lamarkviii]

I got a break in the rain to go outside and check this out further -- the sound seems to me to be coming from inside rather than from under the hood. It doesn't happen so long as the setting is to "automatic" or if I push the flr/defrost button -- but when I hit vent, pnl/floor or just floor, the sound happens.

And thanks so much for the tip on the door. I'll be doing that as soon as this stupid rain lets up.

lamarkviii

 

[lamarkviii]

So problem solved -- but not cheaply, sadly. a/c compressor is gone and it damaged the serpentine belt. But at least now it's taken care of.