heater problem
 

alright everyone, my heater in my truck isnt really working. once it gets to operating temp (180-190*F) the heater blows barely even warm at all. my wifes tahoe runs at 190 and her heater blows us out of the car.

ever since i did the cummins conversion its been like this. i dont see why the motor would matter as long as the water temp through the heater core is hot. and i bought the truck with no engine so i cant tell you if it did it before this engine.

i have a brand new heater core. heater core gets really hot to the touch when at operating temp, thermostat is working well, it just doesnt blow all that well. it blows hard just not hot.

its a 1995 year so i dont think it needs one of those vacuum line operating valves. i have had the dash out and back in i dont know if something got knocked loose, but ive replaced probably 100 of these dashes (literally) and never had a problem. and i am sure the knob is functioning correctly because when i put it on cold it blows COLD.

any ideas? thanks

i know you probably already your doors and your heater controls to make sure theres not cold air mixing with your hot air somewhere :humm:

was it a diesel truck before? I know my 95 doesn't need vacuum for the heater, but maybe a gasser is different.

im with arizona redneck i bet the flow for the air is wrong.

yes it was previously 6.5l before

how would i go about checking that?

i just shooting in the dark but to check your air flow your going to have to probably take out the heater core and dash. which seems like a piece of cake for you. i would also check for loose parts in there in case you bumped something.

ill have the dash out in a couple weeks when it gets back from the body shop. the airflow seems like its good, i mean when it blows it blows hard it definitely doesnt lack airflow. it just lacks heat. is there a valve or something i can manually turn to see if its not letting it go all the way hot and maybe stopping at like 50% heat/50% cold

there is a couple of doors ran by small motors in the heater box to change air flow through the heater core or a/c make sure they are all working good.

here is a good thread to look at. isnt it wierd this guy has a similar problem at the same time as you with the same year of truck!

Heater Flapper - The Truck Stop

hmm ill have to look at it when it gets home. im thinkin my switch is jacked up and not sending fuel signal to the flapper box