Heater blows cool air - heater is not working?

you should firs tfeel the heater core hoses, post back your results, is one hot and the other one cold or significantly cooler? is neither hot, or are both 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.

They both seem to be warm one might be a little hotter than the other.

in that case you should flush out the heater core and then bleed the system of air. if that dont work post back.

I flushed the heater core as suggested and it solved my problem. Thank you very much for your support and ideas.

No more blankets required........ :D

glad it worked, thanks for the donation!

turn on heat and blower works just no hot air. if it is idleling for a couple of minutes and you turn it on it without driving it you get a very faint sense of heat from the air blowing out but when driving you get nothing but cold air. should i automatically think heater coil or are there other things to look at first.

Welcome, what does your temp gage show, does it reach normal operating temp? Are the heater hoses about the same temp? Flow through heater return hose?

temp gauge reads about 160. what i thought was a little bit of hot air apparently is none. the hoses going to the heater coil are warm but not hot

Are you getting vacuum to the heater head (control panel) in the dash, it may not be switching over to heat. If not you will have to track down your vacuum line, it normally is on the passangerside behind the glovebox and is a orange color.

does it matter that when i switch it from cold to hot air you can hear the tone of the blower change but no difference in temp

[quote:d9286700e4="johndvincent"]temp gauge reads about 160. what i thought was a little bit of hot air apparently is none. the hoses going to the heater coil are warm but not hot[/quote:d9286700e4]

If the temp gage is accurate, that isn't normal operating temp, should be higher. You live in a cold climate? The other person has a good idea, also, if those control doors aren't operating like they should.

Hi, I had a heater hose start leaking today, its the one that come from the driver side , lower Rad hose. I replaced it and poured a little antifreeze in there, and thought I was done. Now the Heater will not blow warm air, and the truck will not heat up over 150. It usally ran alittle under 210. I had heat till today. The heater core isn't leaking. I took the cap off and let it run for an hour, I added more fluid, and it still never heated up. I put the cap back on and drove it around the block and it never got over 150 and the heater never blew hot air. I parked it and I took the rad. cap off and it didn't spew coolant, it just sat there, Ive never saw this b-4. WHAT DO I NEED TO DO? Help!!!! Thanks

Try bleeding the cooling system and also check the thermostat.

Subject: Re: no heater
Thanks, I tried that and still nothing, Im wondering if the thermstat is stuck open, Im gonna check it. Where are those bleeder if mine has one? THanks JEff

Check the thermostat

Recheck the the heater hoses and heater core-could be clogging-backflush the heater core,check the temperature valve-if okay could be a problem with the air mix/blend/mode doors or an actuator/vacuum

I have a 98 chevy s10. Its a 2.2 manual transmission. My problem is that it does not run as hot as it should. It seems to run anywhere between 100-160 degrees. I have changed the thermostat, coolant level and for air in the system. I am not loosing coolant also. The truck doesnt over heat and because the T-stat doesnt open i have no heat. Its cold where i live been the weather has never been a problem. Could this be a fan clutch problem, water pump or head gasket? Thanks for your time

do the hoses feel hot when you are running it. also if you can I would suggest hooking up a scan tool and see what your temp sensor is readinig. you may just have a bad temp sensor and a plugged heater core. let me know what you find

Thought maybe thermostat, replaced that, no change. just put a new water pump on, checked that and radiator flows fine. Pulled the heater supply line off the water pump and applied the garden hose to it and get no return whatsoever. It happened so abruptly that I have my doughts that the core just pluged up. Is There a electriical component or fuse to the temp control knob on the dash that i'm not finding? Thanks for any help you might give me.

Start and warm engine for 10 to 15 min check heater core hoses
both should be hot if not one hot and other warm or cold heater core need to be flushed
if both hot
suspect blend door and or its actuator
under dash in the HVAC box
let me know

There is no heat comming through the floor vent. all the other vents work but no heat at the floor.

Hi, the control knob, directs vaccum to different actuators. Could be something wrong with vacuum or actuator. I'd have to look at it.

1996 chevy s-10 blazer, i just replaced the thermostat and still no heat in the cab. Where is the air bleeder valve for the heating/cooling system?

it's probably not that. see if your heater control is getting vacuum and then check your vacuum operated doors to see if they are working or not. that is probably your cause.

Coming to work this morning, I noticed that the heater was not producing ANY heat. What might the possible (most likely) causes be and how would I check for them? Thank you in advance for taking the time to help me.

So it blows at you, it's just cold?

First thing I would check is for low coolant level. The heater core is the first thing that loses fluid, thus heat when there is a leak. If it is low, then fill it, run it, checking for heat and leaks.

heater does not work on 96 chevy s10.Truck has 95 blazer engine 4.3.Water circulates through motor but does not reach heater core.Also overloads fuel

Does the engine reach normal operating temp? Take the heater core supply line loose from engine/water pump, bump the starter, any coolant pump out? Don't start it. Maybe the heater core needs to be flushed?

THis has all been done and there is water getting to and from the heater core.Also has a brand water pump so it cant be that.

In your first post, you said water does not reach heater core.

Are the heater hoses hot? Does the blower motor work? Next, I'd have to get under the dash to see if temp control actuator is working.

We got heat.the wires connecting the heater control were not hooked up.Moving the buttons for some reason did not show this but that is what the problem was.Now we just need to figure out what is causing the fuel overload.Thanks for the reply JDL, appreciate it.

Use a gage and check fuel pressure. Not only check pressure, check that the pressure holds and doesn't drop like a rock, with everything off. Do you have the spider fuel system?

I will need to get a gage before I can check the pressure and yes I do have the spider fuel system.

Some of the national brand autostores used to loan out a fuel pressure gage. 60--66psi.

The heater in my truck will barely warm up. After about 10 minutes it'll feel warm to the touch but will not get hot at all. My temp gauge says about 155 and that's usually as warm as it gets. There's plenty of antifreeze so i don't know what it is. Also air only blows out the top defrost vents no matter what setting it's on.

I'd check the thermostat. The temp you listed isn't operating temp. Some systems, if the actuators are vacuum controlled and vacuum is lost, it will default to defrost.

i already replaced the thermostat and the switch on the dash because it wasn't actually turning all the way to warm but that only helped a little.

The temp you listed isn't normal operating temp. Do you live in extremely cold region? If the heater hoses are hot, maybe an issue with heater core or something under the dash.

On my 1998 Chevy S10 during the summer the a/c stoped blowing cold air, after about a month of slowly getting warmer. The fan portion was still working. Since I live in the mtns. of N.C. I don't have to use the a/c very often ,so I put off fixing the problem. About a month later we had a cool rain and I turned the defrost on the heated air setting to clear the windsheild and there seemed to be no hot air . I then moved the setting to the floor heat and there was no heat there. Now there is no heat or a/c . The fan blower still works fine for the floor, vents, and defrost. I have had no work done to the truck other than a tune up last summer.

Could be a vacuum problem, an actuator or blend door. see below

I was driving, pulled over to get a text message and all heat from vents turned cold, engine temp raised above normal, all corrected when i drove again. This symptom happen about 2 weeks ago, at that time, I replaced the thermostat, and the symptom went away, also the truck has a random miss, according to Autozone plug in thing, the miss is bad from 0 to 25 mph then only slightly noticed at higher speeds. Also i just replaced the oil cooling lines recently. '99 s10 w/ 4.3 Vortec V6,,, 4x4 ext cab