also check that valve that routes the water thru your heatercore,if that barely opens to let water thru,that might be why its luke warm. i hav to check all of mine today, because mine only gets luke warm. on a 35 degree day,i stuck a thermometer in the vent and it only got up to,if i can remember, about 160 degrees, maybe less. should it be at least 190?

 

the crap could clog the valve thus flush your system on a regular basis

 

Ok I have a 97 and I get hot air when I first flip switch to vent but it's NLT hot for about 10 seconds then it gets cold how do I fix this and I don't car if I have to cut and glue something or if I will only have heat and no ac I don't care I just need heat

 

Also I used a infrared thermometer to see how hot coolant was that goes in and out of heater core and it only drops 10 degrees from going in heater core and coming out of heater core I saw the blend door at the hump of the floor that I manually twisted and I felt cold are one way and not so cold air when twisted the other way but where are the rest of the doors etc to get some hot air?

 

The rest of the doors are for your vent controls. I have replaced everything in my cooling system besides the water pump (coming up). With my vents on normal face my ir reads about 100 when fully warmed up and about 110 - 120 when driving. When I move the control to recirc the air (a/c) setting I get about 125-130. What I did for now is took the vacuum control (whatever that little thing is that controls the recirc door off) and zip tied my recirc door open so it recircs on all settings. If you look it is by the p/s kick panel and has a green vacuum line running to it. Pull the glove box and you can see the clip right above the arm running up to the plastic door arm. (one of those things you will know what I mean when you see it.) I zip tied it until I can figure out what is going on.
When I pulled my heater box I checked the blend door for good operation. It moved freely in both directions by hand and even with the motor on it it had decent movement. So I think my blend door is working good. So know I'm still stuck with trying to find out why my heat is still so crappy. Gets old trying to drive in coveralls.

 

Also another thing that was mentioned earlier is the heater control valve. On the later models the coolant is always flowing in the heater core. No matter what the heater settings are. The heater control valve is on the earlier models and I've seen most people remove them. It does not affect the the coolant system in any way and eliminates the chance of that thing going bad. For you earlier guys and gals it might be something worth looking into.