76 COUPE DE VILLE NO HEAT!!! FLUSHED COOLANT SYSTEM REPLACED ANTI-FREEZE, REPLACED THERMOSTAT TO 195 DEGREES, REPLACED A/C THERMO VACUUM SWITCH, HOWEVER FLUID IS CIRCULATING THRU HEATER CORE. THERMOSTAT IS OPENING WHEN HOT. SOMETIMES WHEN RUNNING IDLE AND MOTOR IS HOT, THERE IS SOME HEAT. WHEN I DRIVE, NO HEAT, JUST BLOWS COLD AIR.

If that bottom hose is cold, it sounds like the radiator itself is not circulating.

Possibly plugged or inerporable heater core. Possibly heater core valve (this diverts hot air through your heater system) When you flushed the block, was there a lot of contaminant? 95% of the time, cold heat means thermostat. Also there are a lot of really cheap after market thermostats, you can buy one as low as $6.00. That being said, just because a thermo is new doesn't necessarily mean it opens/shuts when it should. You can look on You Tube on how to test one in your kitchen with boiling water,.

So three basic things affect interior heat temps. Thermostat, plugged heater core/.valve, and insufficient coolant or liquid to tranfser heat. If your interior coolant (engine temp) is working normally and your vehicle reaches operating tempature according to the needle, your thermosat is probably not the cause.

My bet is somehow, your heater core is plugged so that their is not enough "flow"

by flushing the rad, you probably plugged the heater core up. Good to flush the whole system

I drain & fill coolant every 3 years

At about 6 to 9 years, it is a good idea
to change the thermostat.

If you still have little heat, then you need
to understand more about that system to
diagnose

Did the coolant draw back from the container
when it cooled off overnight---- eg: do you have air
in the system.

Check at fill cap & make sure the recovery bottle
is to the cold level

50/50 on anti-freeze--- with distilled water
from super market

I use the max 60/40% on coolant -(water 40%)

You'll need to do some detective work on the overheating issue.
Is the thermostat opening at 195 degrees ?
Is the system full of coolant and no air pockets?
Does the cooling fan come on when the engine reaches 225 degrees ?

Put in a low temp themostat and see if this helps. Also check your mix on your antifreeze. Make sure it is 50/50 or what ever the dealer recommends.

have the coolant system flushed out, you might have a clogged heater core

WATER PUMP FAILURE COULD BE CAUSED BY WRONG COOLANT USE DEX COOL ANTI FREEZE.REPLACE THERMOSTAT AND BOTH RADIATOR HOSES TOP HOSE AND BOTTOM HOSE.SOFT HOSES COLAPSE LIKE PUMP HOSE.IT WILL COLAPSE FROM PUMP VACUUM CLOSING OFF SOME COOLANT FLOW.MAKE THE HEATER CORE NOT STOPPED UP IF SO IT WILL RESTRICT WATER PUMP BYPASS CAUSE EARLY PUMP FAILURE.YOU NEED 50/50 COOLANT MIXTURE YOU HALF WATER AND HALF DEX COOL DONT USE GREEN ANTI FREEZE USE ORANGE DEX COOL.I HAVE 3.4L ENGINE AND 3.1L ENGINE BEEN USING DEX COOL ANTI FREEZE SINCE I HAD BOTH VECHICLES. HAD NO WATER PUMP PROBLEMS.

Since your blower is working and it is a heat issue,thats where we'll start,First thing is have you checked the coolant level in the radiator when engine is cold,make sure it is filled to top,next verify you have coolant in reserve ,Start your van and get it up to normal operation temperature,If your heat gauge on the dash works correctly it should be 190 degrees,Now lift the hood and locate the two heater hoses going into the heater assembly at the fire wall,Both hoses should be hot to hold on to,if both are hot and no heat inside your problem will be the blend air door in heater assembly.
if neither hose is that hot you need to replace the thermostat in the engine to get it up to 195 degrees.
if one hose is hot and one is luke warm then the heater core is blocked and to blame. hope this helps you.

stuck heater contrroll valve

check the upper and lower heater lines to make sure they are hot

also make sure it isnt an air lock
remove lower line check for flow when running