I did the radiator cleaning back in the summer and brought the temo back to 190 pulling, boy was it nasty. Well its finally getting cold in GA and i turned the heat on and its blowing cool air. I cleaned the rad, new thermostat, and cap. Any ideas on why its not blowing hot ?

You would think that if your coolant is 170 then the air should be at least 100, but mine only gets warm enough to defrost the windows. I'll have to check my mix control

I actually get a exponential curve going for vent temps (non-recirculating) and coolant temp. I don't know my exact coolant temp until I get to 130 but I can watch the vent temp shoot up from the time I start it. Meaning that I am getting probably the same temp out of my vents as the coolant is. As the coolant gets warmer, then the 2 relationships start to take different paths. From what I can figure, cold air takes on heat more readily than hot air, so any heat in that heater core while the cab is still freezing is going to be easily pulled away by the moving air and blow into the cab. However, there is a point when the heat from outside reaches its limit because of the velocity going through the heater core. You might notice you get hotter air on setting 3 than 4 because it isn't moving as fast so has more time to grab more heat, but then you aren't getting as much flow so it probably works out to heating the cab the same amount. On recirculate, it runs the already hot air through the heater core and you would think it would pull the entire 190F heat out of the heater core, but it doesn't. I have seen around 160F max on recirculate but the temperature difference isn't enough for it to get much more heat than if it weren't on recirculate. It is like a swimming pool being 100F and the air temp being 90F, that water isn't going to cool very much because there isn't much of a difference. Let it get to -10F and now the pool freezes rather quickly. You can put the fan on the lowest setting and that will give you the highest temp since it needs all the time it can get to pull the tiny difference of temperature away from the heater core, but then you have no flow. It is a very tedious setting if you want the most heat, vent settings even come into play (head/defrost/floor/mix..). Recirculate gives the hottest temperature no doubt, but only on your head so the bottom half of the cab remains cold. What I have found to do is put it on recirculate (setting 3) until your head melts, then put it on head/floor (setting 4), the temp will be a little lower but the whole cab will unite as one perfect temperature and then you simply start stepping down on fan speed, then temperature. The only thing is that the 24V's have that compressor on on every setting almost. I will turn my a/c on when it is on the head vent non-recirc tomorrow and see if it drops the output temp.

Subscribed. I have one of those COLD cabs.Sent from my Kenworth T600 18 Wheeler

Finally figured out what was wrong with my heating/AC system. The "blend door" was stuck. It would open from time to time but not on any regular basis. Took it back to the shop who worked on the whole system and they yanked the dash out finding the problem. Seems that there was a burr on the door that kept it from moving right.

Not sure why it is running that much. Mine doesn't turn on at all unless it is on defrost. I had it on recirculate today and the temp gauge went over 160F coming out of the center vent, my temp thing goes blank after 160 lol. I did get a pic of it before it blanked out. I could barely grab the steering wheel because the vent was blowing on it, scorching my hand.

Is there any difference from 12valve to 24? Are the heaters different too? I don't have recirculate unless its on max AC

Is there any difference from 12valve to 24? Are the heaters different too? I don't have recirculate unless its on max AC

ok i have checked the blend door and it works. The heat gets warmer at idle, on defrost, and on low. it cools off when i turn the fan up. Its ok but we just had a ice storm in north GA and with 15 degree weather its hard to keep the windows defrosted

ok i have checked the blend door and it works. The heat gets warmer at idle, on defrost, and on low. it cools off when i turn the fan up. Its ok but we just had a ice storm in north GA and with 15 degree weather its hard to keep the windows defrosted

Did they check the heater core out and make sure it wasn't plugged?

I will again but i flushed over the summer when i put a vp44 on it