Heater not working

check your fuses to make sure the unit is getting power. then check your actuators in the heater unit pic enclosed. make sure both heater hoses are hot before checking actuators so you know you have heat goin ginto the heater. Check out this guide and the diagrams below.

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

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

A/C works,Defroster works hot, no heat at floor? Manual heat control. No heat at floor even on blend Def/heat, all defrost. I have hot air ,just not at the floor. Please help!!

Under the dash ,i see 2 vacuum actuators that appear to be working when changing the control switch,from floor to defrost.Is the actuator bad or the door the problem? And best way to repair? Please and Thank You.

Hello,

It sounds like you lost vacuum or the mode actuator is not working. Here is a guide to help you check for broken vacuum lines and diagrams below to show you the mode actuator location so you can check it out.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

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

Thanks for this post I have this problem had the vacuum line off the actuator all fixed! I love this site.

my 2000 blazer recently developed aheat problem,my heater throws no heat,and i have already put the new thermostat.blower motor blows great but no heat..

Your t-stat is in bachwards or (more likely) the heater core needs to be flushed out. It is common for a heater core to become clogged with junk.
To check the heater core for blockage-get the engine up to temperature. Feel the heater cores two hoses--located in the engine compartment. If the core is NOT blocked the two hoses will be the same temperature--if it is blocked one hose will have a temperature difference.

My blazer is a 2000 with only 76,000 miles. I turned the heat on this morning, but no heat came out. It was cold air for about 10 minutes. I know it takes time to warm up, but usually by the time I get to work it is warm. But it wasn't. What should my husband do to fix this?

prestone makes a super flush kit to clean out the heater core. I would highly suggest having you local dealer perform this. there is alot of checmicals and time to do this.

why not replace the thermostat first. 99% of time that is problem.

you can try a thermostat but 99.99% of the time the heater core is plugged.

I've never had a core plug up. What causes the blower motor and wipers to both quit working at the same time??

Heater gives low heat.

One hose gets hot the other stays low.
If i turn the ac/heat all off both hose get hot.
I also checked radiator hoses i heat up the engine the hose on the bottom stays cold.
Temperture stays on 200 F
Is the thermostat broken?

Hope that somebody can help me het is getting cold in the Netherlands.
Thanks Gus

Always start with the basics. Check coolant level and condition, leaks, hose condition (soft/mushiness), listen for any strange noise ( tapping or gurgling) from running engine, and coolant smell. You may wish to have a cooling system / radiator cap pressure test done. Also have the tech check the coolant for voltage. (This will sometimes happen to old coolant that has acid build up.)

If the lower radiator hose is a constantly cold, that is the biggest clue. Make sure your tech knows.

Concentrate on these three possible areas: Radiator core restriction or collapsed hose. (Have tech use IR gun to check for hot and cold spots.) , water pump impeller / bearing problem. (Creating restriction or low flow.), Lastly, the thermostat.

Always have the tech do the basic cooling system inspections. There could be more than one problem. Always have the cooling system flushed when service is taking place.

[quote:be99d6615a="jameswia"]Always start with the basics. Check coolant level and condition, leaks, hose condition (soft/mushiness), listen for any strange noise ( tapping or gurgling) from running engine, and coolant smell. You may wish to have a cooling system / radiator cap pressure test done. Also have the tech check the coolant for voltage. (This will sometimes happen to old coolant that has acid build up.)

If the lower radiator hose is a constantly cold, that is the biggest clue. Make sure your tech knows.

Concentrate on these three possible areas: Radiator core restriction or collapsed hose. (Have tech use IR gun to check for hot and cold spots.) , water pump impeller / bearing problem. (Creating restriction or low flow.), Lastly, the thermostat.

Always have the tech do the basic cooling system inspections. There could be more than one problem. Always have the cooling system flushed when service is taking place.[/quote:be99d6615a]

Thanks for your information next week the car goes for service to my garage.
If printed your advice so he will be notifited .

Thanks
Gus Peeters

Thanks for your information next week the car goes for service to my garage.
If printed your advice so he will be notifited .

Thanks
Gus Peeters

I drove for 6 six days with barsleak in the system then the mechanic flushed the system with water the sludge came out .
Fild the system with new coolant heat up the engine and yes the heather is hot and the interieur getting warm i mean hot.
So problem solved the mechanic told me he did a hundred cars with the same problem .
Japanese german american cars so it's not a Chevrolet problem.
Thanks for you support and have a nice christmas.
Greetz Guus

My heater blower works but only blows cold air. I had the thermostat replaced a it was stuck open, heater worked with warm air for one day and then it went back to blowing cold air only.

hi is your temp guage reading normal?
are the hoses to the core hot?
no air in the cooling system and full?
let me know and i will try and help billymac

temp gauge is normal cooling system full, no air not sure about hoses to core. worked fine after thermostat was replaced but only for 1 day

hi well if temp is normal..then hoses to heater core should be hot. if yes they are hot then heater core or blend door not opening. billymac

Blend door actuator is bad. I dont have proper tools to change it (need 7/32 either offset wrench or swivel 1/4 ratchet) cant afford shop right now. Anyway i took off the vac unit that goes to the door (it was easy just clips on) and i used a piece of wire to make the door stay on the hot side. It still only gets slightly warmer than outside air. So i checked the coolant (full) and flushed the heater core for good measure. Still no improvement. Please help.

make sure the blend door is not broken and still blocking heater. you may be turning shaft but door might be broken from shaft. if that is the case then the hvac unit has tocome out to repair it.

The heater has started blowing hot then cold then back to hot, .... on and on. What could cause this?

With the engine at full operating temp and the problem is present, 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 they are..........

The temperature is controlled by the use of an air mix door that is operated by an electric motor/actuator. This door can be jammed or the actuator can be inoperative or have stripped plastic gears internally.

Been chasin', this problem down, and having absolutly no luck. The heater in my girlfriends blazer just stopped working, I flushed the radiator and put new antifreeze in it, it will try to heat at high rpm's but at idle it is like the A/C is on. Thank you for any help.

these trucks unfortunately have horrible cooling systems. i usually find that i have to use compressed air to blow out the heater core. i put a rag at one end then blow through the other, you will be surprised at all the crud that comes out.

I have replaced the thermostat and the heater core and still have problems. Some times it is just mild warm and sometimes no heat at all. How much does a back flush cost?

Are the heater hoses hot when up to temperature? Are there any coolant leaks? Heater core could be restricted or there could be a problem with a blend door not operating correctly.

Heat continually flows into the cabin from the vents. In addition, when switched to defrost, it takes a long for heat to begin flowing from the defroster grille. Heat still flows from the vents while defrosting. Any idea what could cause this? Thank you for your time.

Hi
Most likely a vacuum leak at control head.Pull out controler check vacuum source on purple line. If good maybe select switch the thing with all the hoses attached. If all good then faulty actuator that controls doors to change modes.
Hope this helps
Thanks for donate

Heater blows out cold air

I am giving you a walk through diagnostic on your situation. Just use the link below to get to it;

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

No heat. There are no leaks and have good air flow coming into the car. replaced thermostat and still no heat.

Did some reading and they say maybe the air control valve. Only problem is where do you find the air control valve. But like I said the air is blowing just cold.

Any suggestions would be helpful. Thanks

Make sure the coolant is full. With the engine running, hot, and the heater on high, make sure both heater core hoses are hot. If they are, the problem deals with the blend door in the vehicle. If one is cold and one hot, there is no flow through the heater core. Flush it to see if that helps. If you have a heater control valve (I don't think you do), it will be an in-line valve on the supply line (heater hose).

my heater is throwing out cold air instead of heat

First place to start troubleshooting for this would be to check your coolant level. If that is full, you may have a faulty thermostat. Test thermostat to ensure it is opening at proper temperature range. If this is good as well, you may have faulty or clogged heater core. You can feel the two hoses that connect to heater core ( going into firewall) to ensure they are both hot after engine has warmed up. If one or both are cold, suspect faulty or clogged heater core.

I have had no heat for the past year. Recently had some coolant leak issues fixed but still no heat. Now after it runs for awhile you can smell a hint of antifreeze and almost like it is running hot. Really dont want to have to take the dash off to check the heater core but if that is what it will take i will bite the bullet. My other problem is i recently lost my power locks. Where can i find the power lock fuse.

Well about the first thing is to check the core for flow. The easy way to do that is to disconnect the hoses under the hood. Then connect a water hose to one side and a drain hose to the other. Then try running water through the core. If you get a flow equal to what is going in then the core isn't clogged. If you get less or no flow the core is clogged.

Replacing the core isn't really hard BUT it does take some time. You have to pull the dash panel to get to it.

Power locks are
Fuse 7 under the hood if you also lost the power mirrors check this one.
Fuse 14 in the instrument panel block is just for the locks.

I have a 2000 Blazer six cylinder, 4x4. The heater is not heating up the car. I have replaced the theromstat and flushed out the heater core. Please help,

Try warming the truck, then carefully feel the heater hoses, are they both hot? If one is cooler than the other, you either have more flushing to do, or a replacement job on the heater core. Also if the system has a heat control valve on the heater hose, make sure it is working!