Very weak heat, even after warming up

[Ryan12689]

Hello, I own a 1988 Grand Marquis GS, and I am having some problems with the heat. I recently replaced the heater core, 9-10 hour job, wasn't fun, and I have kept the coolant level topped off, but not too high.
My problem is that when I let my car warm, turn on the heat, it blows out fairly well, but not very warm, not even close to hot.
What I'm thinking is that the heater hoses may be bad, perhaps pinched before they connect to the heater box.
Would anyone have any other ides on what I could do to increase my heat temperature?

Oh, and I also replaced the thermostat just 2 weeks ago.

[Brandon]

How cold is it outside? Do you have a temp guage to check your temp?

[Ryan12689]

It's been anywhere from 20 below to 40 above, Fahrenheit. The temperature outside doesn't make it any hotter, although it does make it feel relatively warmer inside.

[Brandon]

You could take a piece of cardbord and put it in front of your radiator. Just cover half of the radiator. That should make it warmer as your going down the road. Or you could do away with the clutch fan, and run a electrical fan with a toggle switch. That way you have control of the engine heat.

[351m]

Feel the hoses and see if they are both hot when the engine is up to temp. There could still be an air lock in the heater core or lines.

[Ryan12689]

@88_Marquis_302:
I have tried the cardboard trick, it didn't work. That could also be in part that I don't have a grille, I haven't gotten around to replacing it yet.

@351m:
I'll have to try and see if it's an air bubble in the lines. What's the easiest way to bleed it? Just flush the coolant system?

[gadget73]

What temperature thermostat did you install? If its under 180, you will get poor heat performance. Safety thermostats might also do this since they dont completely shut off coolant flow.

Is the radiator completely full? Is the level in the overflow bottle where it should be? If so, the system should self-burp as long as it doesn't have too much air in there. If its really air bound, unhook one of the lines at the throttle body an top off the coolant. Thats the highest spot in the cooling system, and air will burp out of that spot.

Do you have an automatic climate control car? These have their own little gremlins that might make for poor heat. If its not ATC, is the cable hooked up to the top of the heater core box properly? If not the blend door wont go fully to hot.