heater is blowing cool air

[BigBiscuit]

my 88 GrandMarquis is blowing cool air when it should be blowing hot. The heater core is fairly new, I've topped my coolant level, flushed the core with a garden hose, and checked my thermostat which seems to be working fine. i have not disassembled the heater box to see if the cold/hot lever is sticking, but i can hear and feel it move in there, no jamming or extra effort required.

one thing i've noticed is at idle and operating temp the coolant flow thru the top radiator hose isn't as strong as i think it should be. when i grab it, i feel flow but not a hard rush like my other cars. is that normal for these cars? could my water pump be going out? unfortunately, i don't have a temp gauge in the cabin to see if the motor is running hot around town.

any suggesions would be much appreciated. i really want to keep this car on the road. thanks guys.

[Dave84]

mine did the same thing, there is a vaccume line under the glove box (under the dash) going into a goldinsh colour canistor, for your heat mixer flap, pull the vacuume line and plug it off and you should get heat, then in the summer just plug it back in,,,

[Dave84]

could also be your thermostat gone bad

[turbo2256b]

Check for vacuum leaks.

[86GmLsCoupe]

It sounds like your ATC sensor is bad. Dave's fix will hold you over, give you full heat, and will also help you confirm if the sensor is shot. Replacing the sensor is very easy and they're not to hard to come by.

[87_crown_vic]

i noticed when i drove to chicagoto get my tudor that my car was not even hot in the radiator. the heat worked fine but you would think after driving from nebraska to chicago it would be hot. i could pop the radiator cap and dip my finger in it. i have no problems w/ heat or anything. just confused the hell outta me.

[BigBiscuit]

thanks for the advice guys. i'll check for that vacuum solenoid and replace the ATC sensor.

Much appreciated!

[FatNasty]

My water pump started going bad and it was doing exactly that, but i would check the other stuff first

[87_crown_vic]

do you have to remove the glove box, or is it under it. the white CV i just bought isnt blowing warm either. the blower on it works fine, just no heat. i can see my breath and it is a cold ride.

[gadget73]

Open the glove box, maybe you have to pop the stops but you dont need to remove it totally. You should also be able to get to it by removing that cardboard junk under the dash.

[87_crown_vic]

ok...i messed with that stuff and it is still blowing cool...i think the temp contol for hot-cold isnt connected in there. how hard is it to remove and try to get it working or would it be easier to get another??

[gadget73]

If pulling the vacuum hose won't get you heat, there is some other problem. If the temperature selector is set to cold, the hose should have vacuum. When you pull it, you'll hear the door shut. Did you unplug the gold can that has the hose facing the glove box door, or did you get the one under the dash close to the passenger side fender? One under the dash just above the cardboard junk is a fresh air / recirc door. It wont have any effect on heat output. No vacuum on that defaults to closed.

[monterey1962]

Glad I seen this thread. CV heater is blowing warm and going cool after a while. When I changed the core (twice) I may have gotten a little rough with the vac motor on top of the plenum.

[87_crown_vic]

ther are 2 of those canisters almost under the ashtray under the dash, and there is one that i saw when i fliupped the glove box down. i undid all of them. the one i saw behind the glove box works the flapper air door. it is shut. is there another i am missing???

[gadget73]

Nope, those are the only ones.

Justin: failing interior temperature sensor will do that. Mine used to wander all over, new sensor and its all better.