Heater no blowing hot?

jessie, it sounds like you have a completely plugged heater core. Does your vehicle have a valve on the heater core supply hose? If so, does the valve move?

My 1998 Chevy Envoy heater will only blow cold air... this started est a month ago...

Check thermostat if its stuck open, heater core if its clogged and the air blend door if its stuck in the cold position

My heater does not get hot. The temp is 198deg. It has a computer climate control heater.
Can it have a weak water
pump.

no weak water pump. most likely your heater core is restricted due to crud built up in it. try removing the hoses from your heater core and blow out the heater core. i usually fill the heater core with water and blast compressed air through it. i put a rag at outlet and observe all the crud that comes out. this usually fixes this problem.. remember feedback and votes are appreciated if i have helped you

I had heat in my blazer.I had pinhole on heatercore hose.I cut off the bad spot.hooked hose backup lost heat.I replaced thermostat had radiator flushed still no heat

You probably have air trapped in the heater core. That's why we usually use vacuum to fill the cooling system.

How do I get the airpocket out

It should work out on it's own.
With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch.
If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. it is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.

Heater problem
1998 Chevy Blazer Engine Size unknown Four Wheel Drive Automatic 165184 miles
----------------------------------------------------------------
we just changed the thermostat and before we did that the heater was just blowing cold air and then we changed the thermostat and it started working at first but it seems it is only blowing hot air like it should when it is sitting there but when you start driving it blows kinda warm air but mostly cold so what else could it be. we had a new radiator installed about 6 months ago and a new engine so everything has been replaced.

[quote:129eaaf982="AmyMT1974"]Heater problem
1998 Chevy Blazer Engine Size unknown Four Wheel Drive Automatic 165184 miles
----------------------------------------------------------------
we just changed the thermostat and before we did that the heater was just blowing cold air and then we changed the thermostat and it started working at first but it seems it is only blowing hot air like it should when it is sitting there but when you start driving it blows kinda warm air but mostly cold so what else could it be. we had a new radiator installed about 6 months ago and a new engine so everything has been replaced.[/quote:129eaaf982]



Check and adjust coolant level
try to flush heater core

Heater problem
1998 Chevy Blazer 6 cyl Four Wheel Drive Automatic

i just recently did a head job on my blazer.after putting the heads back together the heater does not work.the fan doesn't blow period.if i run the fan directly to the battery it works,sounds fine.any ideas,i know i could run a 3speed toggle but id rather use the existing system.

When you say direct to battery are you supplying it with power and ground or just power
if just power you should be able to control the speed from the switch and in this case I would suspect a bad fuse ,wire and or relay
let me know

*****************************************
need manual CHECK IT @
https://www.2carpros.com/kpages/auto_repair_manuals.htm

i supplied both power and ground.checked all the fuses,inside and under the hood.

what happen if you supply power only or ground only
let me know

thanks i will in 1 hour i really appreciate your responses.

1998 Blazer 4wd
123k
automatic
4wd
4dr


Ok the heat in the car does not work. Oil was replaced 2 weeks ago during tuneup. Just started needing the heat and it doesn't work.
The AC blow extremely cold when on. I believe the switch works too because i can set it to auto and it will go on and off at different levels. What is causeing this and how do i fix it?


Thanks
Brian

are both the hoses going into the heater core hot to the touch? if both are then check the blend door. if one or none is id bleed the coolant sensor

Ok, will check hoses tomorrow, what isthe blend door? Is it the piece that sepeartes the hot and cool water in the heater core?

Thanks

he,s right if the hoses are hot then the unit that separates the cold ac air from the hot heater air can become jammed and not move from cold to hot when you turn the temp knob possible causes are , debris down in the heater box such as a straw, tooth pick ,pen or pencil, or simply the blend door actuator has failed , if hoses are not hot to touch a simple thermostat could be the culprit,,, rick

The door is a little plastic door that causes the air to be pushed thru the heater core when it is hot. And when it is set to cool it bypases it.

My truck fogged up last night and i started smelling antifreeze, but i still get heat, but if i turn it on it fogs up really quick now i have no moisture on my passenger side carpet but i was told it was the heater core. But could it be the t-stat?

nope it 's a heater core. the antifreeze is probably going out your a/c drain under the truck. This one is'nt easy as you haveto pull the dash to put the heater in...

my 1998 s10 blazer is having a heater problem it blows out heat but not sufficiently enought the blower motor is pushing out the air its just not heating up as it should. theres a slight antifreeze smell i was just wandering if it a heater core problem and i have to replace it or try to get it flushed if it could be clogged. any answers would be great i need my heater considering its -11 out now!

if there is no coolant leakage anywhere (around heater hoses under hood or in cab on passenger side floor) then most likely the heater core needs flushed. if there is leakage then it will need replaced , or perhaps just a hose to the core needs replaced

I have a new theromstat and its working fine. I put antifreeze in the radiator and still isnt recieving any heat

  After the engine has run for about 30 minutes or so, what is the engines' temperature? After this period, is there any pressure in the radiator? Also after this period, Is there a big difference in the temperature of the upper radiator hose, compared to the lower hose? Are they too hot to touch for a while?

Heater problem
1998 Chevy Blazer 6 cyl Four Wheel Drive Automatic

no heat coming inside no fuses blown get air but no heat thermostat new computer controled

engine reaching operating temp ?
if not check thermostat and coolant
if it is check heater hoses both should be hot if not heater core need to be flushed
if they are suspect blend door
good luck

need manual CHECK IT @
https://www.2carpros.com/kpages/auto_repair_manuals.htm

i am having problems with my blazer not getting hot the heat is luke warm and the temp of the truck never gets above 170 i have replaced the thermostat twice and still same thing also there is no pressure on the upper radiator hose ever i can drive down the highway for hours and still no pressure on the upper hose what else could it be

it could be the water pump or the lines are crossed going to the heater core

me too i have the same problrm like jamesmott82 and after i saw that the lines are not good