Luke Warm Air...

[slategrove]

It's getting really cold here in Central Illinois, and my heat is barely luke warm. I'm wondering if I need a new heater core?

I put in a 195 degree thermostat, instead of the 180 I was running before, and that didn't make any difference... The temp is running around 210 and I don't have any real heat coming out of the vents!?

I don't have any antifreeze leaks, sweet smells, etc...can the core just go bad?

What do you guys think?

[redbaron69]

it could be stopped up. check and make sure your coolant level is full.

[jay6891]

Your outside duct work maybe stopped up with leaves and mouse nests. How much air you getting out the floor vent? My truck had a Fred Flintsone floor in it and it would keep you warm after I cleaned out all debris. Granted Im in Arkansas and you in a colder climate.

[Stubbs67]

flush it both ways, then top up the system and try again

[Lee H]

Do you have a malfuctioning shut off in the engine bay? Check for proper heater hose routing. With the engine up to temp do both heater hoses feel the same temp, are they both hot, is one cooler than the other by the core?

[slategrove]

it's full of coolant

both hoses ar hott! closest to the heater core

and I have plenty of air coming out of the vents

this must mean that it needs to be flushed...correct? Can I do this with a garden hose, or does it need more pressure than that?

[redbaron69]

i have flushed them with a water hose, just may take "multiple" flushings to get it loosened up. if flushing helps i would replace the core first chance you get.

[68 Stepside]

I've run into the same thing before. Barely had heat until I replaced my heater core, it was plugged up badly. You can try flushing it for now, but it would probably be a good idea to replace it in the spring.

[swamp rat]

You should also double check that the cable actuator is actually opening the flap door that allows the heat from the core to enter the fan box, i unhooked my cable and listened for the door movement.

from what i have read here on the forums there is a small access door you can open to look inside to see the flap door, but i beleve you may have to remove the glove box liner to access it? I have not done this, just read something about it.. but as also posted above the outside duct work can get clogged up with debree too, this will require removing the cowel so you can get a small vacume hose inside.

[hayhauler71]

As said before back flush the heater core a few times with a garden hose should push the blockage through. Heck I had a 08 Buick with 50000 miles on it that the core was plugged it just happens

[slategrove]

Went to the local parts store got a section of 5/8 hose (so I could flush by using the wand at the carwash), got some extra coolant (so i could top it off afterwards) and put $2 in at the carwash...did it all in the bay at the carwash and took about 15 minutes from the time I pulled in, until I had hot air again.

Thanks guys, and I'll replace the core in the spring!

[C. M. Wolf]

Originally Posted by slategrove

It's getting really cold here in Central Illinois, and my heat is barely luke warm. I'm wondering if I need a new heater core?

I put in a 195 degree thermostat, instead of the 180 I was running before, and that didn't make any difference... The temp is running around 210 and I don't have any real heat coming out of the vents!?

I don't have any antifreeze leaks, sweet smells, etc...can the core just go bad?

What do you guys think?

Hello Cuz,(I used to live in Pontiac)...

Two words, "Silicon Silicate", this was a common additive put into the cheaper antifreezes and tended to completely clog vehicle radiator and heater core passages. I do not know how to remove this type of clogging other than to replace the cores.

The older GM (Blue),Glycerol antifreezes were the absolute best over-the-counter antifreezes a person could find,(kind of a shame that GM realized this and the price began to reflect it).

I do not know for sure if this is what is aflicting your truck, but I'd suspect it and change out the heater core as soon as you can. (Especially if a couple of flushes and cleaning out the other system areas aren't giving you the results they should).
You could flow-test the heater core by removing the hoses and running water through the heater core. If it runs easy, it may not need replacing, if it only barely trickles through, it's new core time.

Other things I've done to help harm my trucks is wrapping the heater hoses in neopreme insulation that fits around the hoses,(Ive found these at most home centers. the stuff comes in 4' and 8' lengths with a split down the center with adhesive in the split to stick it together), and blocking off the front of the main radiator's air flow about 40-60%.
Another thing to look for is good weather seals on your doors & windows,(lots of drafts from aged weather stripping just defeats any heater. This brings me to the Kick Panel Vent weather seals. If these are cracked or missing, it may be hard to tell if your heater is even working well or not in the winter.

My regular driver,(C20), was built to pull horse trailers in temps that match Death Valley,(huge cooling system), which all needed to be compensated for when I moved it to NV, CO and later to MT. I'm still learning about all what can be done with a heating/cooling systems on these trucks.

I guess maybe "Seat Warmers" if I move any farther north...

IHTH

Michael

[ERASER5]

Hey Slategrove! I see you are from Normal. My brother lives is Bloomington, close to the airport.

Glad you got your heater fixed. It is toooo early for this kind cold stuff! I usually end up blocking part of the radiator off with card board. The plastic kind works best.