heater not working?

Hi:
With the engine at operating temp and the heater on, feel both heater core hoses. Both should be hot. This guide should help us fix it

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

and this video

https://youtu.be/SNRb6pSwYuU

Let me know what you find.

Joe

I felt the lines to the heater core, the feed line was hot the return line was cold. I disconnected the lines and blew in through the return line with an air compressor. I now have heat.

Glad to hear that it worked. It must have been plugged. You may want to flush it when the weather gets a little better.

Joe

have replaced thermostat, flushed heater core,still get heat sometimes, but does not last. tested the temp control switch has 9.92 ohms, and it is variable with turn of the control shaft. what does this temperature control switch actually control? Is it a valve? the truck runs great. runs about 210 degrees and is full with antifreeze. does not overheat. It used to have heat really fast, the heater core has been replaced, and worked fine for a winter, it was working then it started to have sometimes heat.

There is a temperature blend door actuator to control the temp. Here is a guide to show you what you are in fro when changing it out with the location of the actuator for you car below.

https://www.2carpros.com/articles/replace-blend-door-motor

this guide can help as well

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

With the engine up to operating temp are both the heater hoses going into the heater core getting too hot to hold?

Check out the diagrams (Below). Please let us know what you find.

Cheers,

With the truck up to operating temperature, the supply hose (the larger of the two) is hotter than the smaller one?

Is sounds like the heater core working correctly, did you get a chance to check the actuator?

No, I can hold on to both of them. Is there something that I can pour into the heater core to flush the dexcool that usually plugs the core?

Your not getting coolant circulation if both your upper and lower radiator hoses arent getting too hot to hold?I would address that maybe you got a bad thermostat?Did you put the thermostat in correctly?

I changed out the actuator and now I have heat again! thank you so much I has freezing. I love this site

You welcome.

If I pull return line off heater core run the motor coolant will circulate. When hook it back up have heat for couple minutes then lose it again. Seems like it loses its prime, could this be a water pump problem? I have flushed heater core and truck runs normal temperature around 190.

Good morning,

When the hoses are hooked up, do both feel hot?

It sounds like the core is clogged. Did you flush it both ways with a garden hose? If you did then most likely it is a bad heater core.

If you had a bad water pump, it would run hot and possibly overheat.

Roy

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

https://www.2carpros.com/articles/replace-heater-core

When I am in park the heater blows cold air and I can smell anti-freeze. When I am driving the heater works perfect and there is no smell. Any info would be great.

Try replacing the thermostat and see what happens. The heater is getting cold at park bcuz the water pump is not turning that fast along with the thermostat sticking open compared to higher speed.

I have a 2003 chevy s-10 with a 4.3 liter motor. My question is when I turn on the heat it blows cold air. The thermostat is working fine running about 190 degrees what do you think is causing this and what or how should I check it.

i think the thermostat is stuck closed and is not allowing the hot coolant to the heater core.

My 03' Auto S-10 is at 60,000 Miles. I recently discovered (during the cold winter months) That the heat does not work. It only blows cold air. The fuses are fine, the heater core has no leakage or smoking (I have had 2 blown cores in the past and do not believe it is the problem), the AC unit works just fine. I am at a loss to what the problem may be. Any suggestions?

Your thermostat is probably stuck open. A thermostat works as follows.. When you start your engine the coolant is cool. At this point the thermostat is closed, not allowing coolant to run through the radiator--where it is cooled. However your water pump is always pumping coolant somewhere, and regardless of whether the t.stat open or closed, the coolant is usually flowing through the heater core and the engine. As the engine creates more heat the coolant heats up also. When the coolant reaches 185 degrees or so, the thermostat opens and allows coolant to flow through the radiator. As air passes through the fins of the radiator, the coolant is cooled down to safer levels for the engine. If the thermostat sticks open or fails open, the coolant will constantly flow through the radiator and be constantly cooled. This will not allow the coolant to heat up thus you are left in the cold. Your engine will be happy, but unless you like to be cold, you will not be happy....

BTW-- a thermostat can stick or fail closed which will cause over heating and eventualy engine failure, so have your thermostat checked and/or replaced. Let me know how you make out.....

my heat doesn't work until my engine overheats and the heat kicks on and cools my engine back to normal temperature... ???

Try replacing the thermostat and make sure the heater core is not partially clogged-up don't work come on back.

I have a 2003 s10 the ac works fine and the blower is working and the engine is heating up but I'm getting no heat what should i look at?

Is the coolant full? WIth the engine hot, running, and the heater on, do both heater core hoses get hot?

Fan works great. Coolant level is correct. All HVAC fuses are ok. Engine temperature correct. A/C works fine. When heater is turned on, nothing but very cool air comes out. Tried moving heater temperature control back and forth several times. Tried switching to different heater functions(floor, defrost, dash, etc.) several times. Blows cool air in every setting.

Test the thermostat might stuck open and also the heater core if its clogged-up/coolant level

Heater blows only luke warm air. Heater core has been flushed. 195 degree thermostat replaced. Anti freeze replaced. It has no troulbe blowing cold air, just not warm air.

is your heater control valve oppening properly? to test feel the heater core hoses, if they are hot like usually then it is probably the blend door, if you notice they are warm not hot then you may want to check your heater control valve.

I lost the heat in my 2002 S10. I replaced the thermostat with no results. The temp. gauge gets to its normal location in the same time as always. I've had no trouble with overheating. It looked fairly clean in the radiator when I had the cap off. My question is, do you feel my problem is with the heater core, or the temp control knob on the dash? Thanks for any help.

Welcome to the forum, does the blower motor work? Are the heater hoses hot? Can you check for circulation through the heater core?

The blower motor is working fine. I'm not sure how to check for blockage in the heater core. Can you tell me where to find the heater hoses? If the heater core was blocked, would I have overheating trouble? The heat did come back for about 5 minutes after changing the thermostat, but hasn't since. This was after turning the temp control knob back to cold then hot repeatedly. I don't know if this was coincidence or a problem with the temp control. Thanks again.

The heater hoses should go to firewall, passenger side, they attach to the heater core. I Tried to find a picture of attached heater hoses, couldn't find one? Two hoses from engine block to heater core. If I take a hose loose, I take loose from engine block, bump starter, no start. see if coolant comes out of return line. I haven't found anything on heater hose routing.

mechanic says that the radiator in plugged up and
tried to flush it out. The coolant is the color of mud
or coffee with cream(light brown). Last night the
water pump blew out. What's going on?

tmike

you have an old case of "somebody put the wrong coolant in" and it reacted and became sludge.... usually hot water out of a garden hose can flush it out, but if its real bad, be prepared to replace the radiator... as far as no heat goes, that can be flushed out 80% of the time.... disconnect the 2 heater hoses that go the the heater core, and put hotwater through a garden hose through one hose, you should see nasty brown sludge come out of the other... if so, then you have flow through the heater core, and saved 8hrs of time to replace it...

I have a 2002 chevy s10 4x4 automatic. The heat sometimes works and other times blows cold when on the heat selection. I have changed the thermastat and anti-freeze. Sometimes the lines going to the fire wall inside the engine are hot and other times cold. I don't know what it could be. Is there a vaccume of some sort that draws the coolant to the heater core. Or could the head control be bad. please help!!

Jersey getting colder!

[quote:97570284c5="peteyg"]I have a 2002 chevy s10 4x4 automatic. The heat sometimes works and other times blows cold when on the heat selection. I have changed the thermastat and anti-freeze. Sometimes the lines going to the fire wall inside the engine are hot and other times cold. I don't know what it could be. Is there a vaccume of some sort that draws the coolant to the heater core. Or could the head control be bad. please help!!

Jersey getting colder![/quote:97570284c5]
try flushing the heater core

Remove two heater hoses
( engine side)
Use a water hose run throw one and watch the pressure and amount of water coming out throw the other side
untill clean and good flow
place back and run truck

Good luck

I have a 2003 S-10 ZR2, 85000 miles
when i frist start the truck i have little
heat coming out of dash vents, once i turn to the other vents I get cold air, and it stays that way on all vents.I have the heat all the way into the red, but still no heat. not sure if i need a flush or new thermostat. Do you have any suggestions.
Thanks for any help. Rick.

The hose on the left of the heater core is
very hot, and the one on the right is cold.
Does this help at all.
Thanks for your time..

Ok I Got It Fixed Finaly.
I Just Did A Quick !0 Min Flush Job
On The Heater Core And Now I Have
Alot Of Heat. Amazing What A Flush Job
Can Do..

My 2003, S-10 heater has hot air coming out the vents all the time, I can turn it hotter, but not completely off

If you always get heat, you need to check the blend air door. It determins if you get heat or AC. If it is stuck, then you may not be able to shut it off.