no heat in new truck

[jasonroman]

So this morning I get out of work at 7 am. About 35 degrees out. Foggy window so I put defrost on. Clears window. A little later I chose to switch to heat. And nothing. Not cold air but definitely not hot. So no heat in new truck will not be good for the up coming winter. what do I need to check? Added to the list of things to fix......Heat
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[2badgn]

Check antifreeze level, thermostat, hoses and heater core in that order.

[SCOTI]

Check coolant level (if there's not enough fluid in the system it has a hard time getting pumped through the heater core) & if there's a heater bypass valve make sure it functions correctly (these prevent hot water from entering the heater core thus keeping the pass compartment cooler).

[donut]

x2, did you have heat coming out the defrost? If not you could have a sticking flapper in the heater box.

Another thing, if everything else checks out, have you changed the heater core lately?
Not saying it's bad, but when I changed mine, it had an inch of old dog fur insulating it.

[jasonroman]

Thanks for replies.
I'll check it Sunday when I have some time.
Not sure if defrost was hot or not. Just know it was clearing window in the morning.
Never changed heater core....no clue how
Trucks about 2 weeks old been messing with other stuff till now
Hopefully its a minor thing......hopefully
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[rs72z]

Originally Posted by jasonroman

Thanks for replies.
I'll check it Sunday when I have some time.
Not sure if defrost was hot or not. Just know it was clearing window in the morning.
Never changed heater core....no clue how
Trucks about 2 weeks old been messing with other stuff till now
Hopefully its a minor thing......hopefully
Posted via Mobile Device

Before you start replacing the heater core try to back fkush it first. Take both hoses off and take a water hose and flush it out both directions and see what comes out. I need to do mine it's just barely blowing warm. Also check the tstat like someone else said.

[old Rusty C10]

most of the time its something stupid like low coolant or a thermostat.. the other issue is usually the flapper door on the box.. Unless you have no heat or a leak in the passenger compartment the heater core is usually good.
CHeck to make sure when the truck is at normal operating temperature that both hearer lines on the motor are hot.. if one is hot and one is cold then there is a blockage of some kind in the heater core

[76stepsidechevy]

I've got the lukewarm heat going on too, its warm if you put your hand right under the vent but it doesn't really make it into the truck. About halfway through my half hour trip to work its not cold anymore but its not warm either. I tried flushing the core about two weeks ago and it didn't really get any better. I did notice a bunch of rotten foam blowing out of the vent and defrost when I first got the truck im assuming that was a seal on the flapper. Im about to bite the bullet and get a new heater core. Everything else has been done.

[donut]

I may have worded it wrong, If it's not leaking or plugged up, don't change the heater core. What I was trying to point out, is after 30-40 years, the fins on the heater core more than likely need cleaning. When I had mine apart, there was an inch of dog fur on the fins, and a mouse nest in the box.

What do you have for a thermostat? Cool water in= cool air out. In ME, I didn't get decent heat in the winter until I went back to a 195 thermostat and blocked most of the radiator. Truck used to run cool anyway and plowing with the window open I wanted GOOD heat.

[Telecasterjoey]

Both times I lost heat in my vehicles it was my thermostat.

[76stepsidechevy]

Originally Posted by donut

I may have worded it wrong, If it's not leaking or plugged up, don't change the heater core. What I was trying to point out, is after 30-40 years, the fins on the heater core more than likely need cleaning. When I had mine apart, there was an inch of dog fur on the fins, and a mouse nest in the box.

What do you have for a thermostat? Cool water in= cool air out. In ME, I didn't get decent heat in the winter until I went back to a 195 thermostat and blocked most of the radiator. Truck used to run cool anyway and plowing with the window open I wanted GOOD heat.

thats a good point about the fins being plugged up although with the effort involved in getting to the core to clean it out and the price of a new one it probably makes sense to change it. With my typical luck I would clean it all up nice and put it back together and the thing would start leaking the next day.

Im running a 195 thermostat now and both hoses feel hot to the touch under the hood. Maybe your right and the fins are packed full of junk, I know all kinds of rotten foam blew out the floor vent and defrost for a while when I first got the truck, god only knows whats still in there.

[SCOTI]

Originally Posted by 76stepsidechevy

thats a good point about the fins being plugged up although with the effort involved in getting to the core to clean it out and the price of a new one it probably makes sense to change it. With my typical luck I would clean it all up nice and put it back together and the thing would start leaking the next day.
Im running a 195 thermostat now and both hoses feel hot to the touch under the hood. Maybe your right and the fins are packed full of junk, I know all kinds of rotten foam blew out the floor vent and defrost for a while when I first got the truck, god only knows whats still in there.

x100. Do not go through the effort just to put a 20+ yr old core back in place as relatively cheap as they are.

[mdb]

No hot air (or alternating between hot and cold) can also be cause by the smallest pinhole leak in the radiator. Watch your engine temperature gauge, if the temp jumps up driving around town then drops back down on the highway that would be a leak in the system somewhere.

I figured this out 200 miles into a 1000 mile trip last winter haha.

[jasonroman]

Originally Posted by old Rusty C10

most of the time its something stupid like low coolant or a thermostat.. the other issue is usually the flapper door on the box.. Unless you have no heat or a leak in the passenger compartment the heater core is usually good.
CHeck to make sure when the truck is at normal operating temperature that both hearer lines on the motor are hot.. if one is hot and one is cold then there is a blockage of some kind in the heater core

well trucks at the shop for inspection, and a 3rd check at front end.
not sure what or where the flapper door is....
p.o was said to have just changed thermostat.....

now, as for leak in passeger side. nothing leaking now, but there is a stain in the floor mat.
guess ill have to take a look at the book and see what lines your talking about that should be hot.
worked today, and was supposed to get the truck back from that guy by 3, but he said, weather backed him up. so hopefully tomorrow, hell get done early enuff for me to take a a look.

[old Rusty C10]

even tho this is a pic of an older truck (67-72 genre) this shows you the heater hoses. This truck is an air conditioned truck.. the heater hoses hook up in this area and have no metal on them like air conditioner lines.. one should go into the water pump or intake manifold

[tucsonjwt]

Quick check - with engine at normal operating temperature and running at idle, and heater on, hold on to the heater hoses and see if they are both warm to almost too hot to handle - if so, your radiator and thermostat are relatively OK. If this checks out, stick your head under the glove box and use a flashlight to see if you can detect any seepage around the air distribution box and also pull back the carpet to see if the backing or pad or floor are wet or show signs of wetness. Leaking heater core should leave an oily film on the inside of the windshield or you should have scent of "eau de antifreeze" in the cab. Also, as previously mentioned, you can have a plugged heater core and reduced heating. Buy only a copper heater core, not aluminum, for about $30 or less. Replacing a heater core is time consuming and you are working on your back a lot but it is not technically difficult, especially if you don't have A/C. You can find some good pics and info on this on this forum.
One general note - if you have any loss of coolant you have a cooling system problem or engine issue (like blown head gasket - should show white smoke on start up.) Top off your coolant and make sure the radiator is full when cold. Check the coolant when cold at least once a month - if the level has dropped at all you have a problem and should look for it. Water pumps are often hidden leaks because they can leak from the bottom weep hole and on our trucks there is nothing below the weep hole, so the coolant drops directly on the ground with no sign of leaking.

[jasonroman]

Thanks for reply. Truck definitely smokes white on start up. And as I mentioned before the passenger side floor mat has an ugly stain on it. Think it was 2 days before I checked for heat that my brother in law was in truck,saw stain and asked if my heater core was bad....how do I know if head gasket is bad? List keeps getting bigger.
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[old Rusty C10]

the easiest way to see if you have a bad head gasket is to look at your motor oil and see if it looks like day old coffee with milk in it.. if there is lots of white smoke all the time through the exhaust you may have a headgasket issue... after that you need to do a compression test on your cylinders to see if there is leaks on the inside between one or two of the cylinders.. more than likely if you drive this truck you dont have a head gasket problem..
Id check the heater core out good and if the stain is getting bigger its prolly leaking

[jasonroman]

Well. Didn't get truck back till 630 Sunday....2 days for inspection and dude didn't get a chance to look at front end?
Well trucks inspected.....anyway, thus morning I checked to see if tax was full the far was almost full....looking in thru cap I noticed fins on tax are covered with some white crap.
The overflow bottle...not sure if that's right term was low.
So I added some.
The defrost works fine. Sometimes I feel it come out warm others not really warm
Stain is on passenger side but don't see any water leaking.
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[85gmc2tone]

maybe your heater rad under the dash is bad if its leaking in the floor
. sry couldnt think of right name

[jasonroman]

Must have leaked at one point, but I've yet to see a drop of water anywhere
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[shloopter]

I had cold air. Flushed the core and that fixed it. Then the flapper door mechanism broke and it got stuck in upper vent mode. I took it apart and made a bracket out of sheet aluminum and that fixed it.

[jasonroman]

Originally Posted by shloopter

I had cold air. Flushed the core and that fixed it. Then the flapper door mechanism broke and it got stuck in upper vent mode. I took it apart and made a bracket out of sheet aluminum and that fixed it. Attachment 823754

Attachment 823755

thanks for pics. question. can i get to box thru glove box?
would i be able to tell if p.o changed the box and thats y i dont see water drip.?

[motornut]

you won't get to the back side of the box to see the core you have to remove it from inside the engine area
how much water to anti freeze do you have ?
a low mix will go slushy, might get close to freezing, and not heatup right
if he changed it the bolts under the hood might be cleaner/scratched from doing it,
make sure the clamps on the core, at the firewall are tight ,not pushed on too far, loose leaking behind it
and under the heater box at the lowest point (engine side)is a hole to drain water out look for it,clear it out too,poke small nail up...
you can check the flap tho by removing the tube behind the glove box.
but if you hear it moving,it's prob working