Heater only blows luke warm air

There is a tech bulletin on this,It is attached below and guide

https://www.2carpros.com/articles/car-heater-not-working

Check out the diagrams (Below). Please run this test and get back to us.

Thanks for the info on the blend door cable. I removed the 7 screw cover for access to the heater core. After moving it both with the cable and without it did not appear to close completely. I used a hook shaped screwdriver and was able to reach in and rake the bottom of the plenum next to the door. I heard a rattle and was then able to squeeze my hand in and discover an ink pen apparently had fallen through the defrost and blocked the door from complete closure. After removing the pen and reassembling the door the heater now functions properly and blows 125 degree air.

Nothin like stayin' warm!

My heater in my F250 blows cold air. I was going to replace the heater core but when I take the screws out of the plenum I can feel hot air coming out the bottom, so I don't think it's the heater core. My assumption is I have an actuator not functioning properly. Any ideas how I can check this.

Are both heater core hoses getting hot?

Yes

My heater doesn't seem to get hot. The AC works fine, but when I switch to heat it doesn't warm up. The temp gauge works, the hoses to the heater core are both warm. I took the cover off the heater core and there is hot air coming out the bottom of the cover. It doesn't seem to blow much air when I switch to defroster either. Any ideas? No matter where I set the knob (floor, vent, or defroster) I don't get hot air. I checked the knob for the heat control and it seems to be working properly.

is the blend door motor moving the way it should to allow heat into the truck??

Roy

I have a 94 Ford F250 regular cab 2wd. It has the 460 engine and a 5spd. The a/c and heater are not working. I can turn them on but there is no cooling and there is not heating. I am not that concerned with the ac, however I would like to heater to work. Someone advised me that it may need a new heater core. Is this something difficult to change or repair?

i would try the flushing the heater core first. remove the heater hoses going to the core and flush out the core with a garden hose.

I have a heater in the pickup that will not blow warm air into the cab. The thermostat is good and the heater core warms right up and the front passangers feet will get warm fast. But if I try to use the defrost or thed vents all I get is cold air. I have looked all over for debris and I have checked the electrical system. What do I do its cold here and I have small kids.

FUNCTION SELECTOR VALVE Place function selector knob in specified position. Using a vacuum gauge, check for presence or absence of vacuum and compare to VACUUM DISTRIBUTION table. If test results are not as specified, check for kinked or broken vacuum lines. If vacuum lines are okay, replace function selector valve. See Fig. 1 . VACUUM DISTRIBUTION Selector Knob..Outside/Rec.. Panel/Def..Floor/Def Position.............Door...........Door..........Door OFF...................V.................V..............V FLOOR..............NV...............NV.............V VENT................NV...............V.............NV MIX...................NV..............NV............PV DEF..................NV...............NV............NV Vacuum (V), No Vacuum (NV), Partial Vacuum (PV).