Heater not working

Tiny
ECW45840
  • MEMBER
  • 2000 CHEVROLET BLAZER
We get freezing cold air out but the blowers aren't working and the controls for the ac and heat and temperature etc isn't working at all
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Saturday, December 3rd, 2011 AT 7:34 PM

39 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
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.
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Saturday, November 14th, 2020 AT 4:01 PM
Tiny
PAUL PATTERSON
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET BLAZER
  • 160,000 MILES
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.
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Saturday, November 14th, 2020 AT 4:07 PM (Merged)
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
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.
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Saturday, November 14th, 2020 AT 4:07 PM (Merged)
Tiny
  • MEMBER
  • 0 POST
Thanks for this post I have this problem had the vacuum line off the actuator all fixed! I love this site.
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Saturday, November 14th, 2020 AT 4:07 PM (Merged)
Tiny
CHOPPER21
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 100,000 MILES
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.
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Saturday, November 14th, 2020 AT 4:07 PM (Merged)
Tiny
PEAR69
  • MECHANIC
  • 1,482 POSTS
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.
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Saturday, November 14th, 2020 AT 4:07 PM (Merged)
Tiny
KSANZNAK
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 76,258 MILES
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?
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
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.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
GARYW2010
  • MEMBER
  • 4 POSTS
Why not replace the thermostat first. 99% of time that is problem.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
You can try a thermostat but 99.99% of the time the heater core is plugged.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
GARYW2010
  • MEMBER
  • 4 POSTS
I've never had a core plug up. What causes the blower motor and wipers to both quit working at the same time?
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
DRUMRAMMER
  • MEMBER
  • 3 POSTS
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 42,300 MILES
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
JAMESWIA
  • MEMBER
  • 9 POSTS
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.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
DRUMRAMMER
  • MEMBER
  • 3 POSTS
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
DRUMRAMMER
  • MEMBER
  • 3 POSTS
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
GRANDMALINDA
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 11,900 MILES
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.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
BILLYMAC
  • MECHANIC
  • 2,204 POSTS
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
GRANDMALINDA
  • MEMBER
  • 2 POSTS
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
BILLYMAC
  • MECHANIC
  • 2,204 POSTS
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
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)
Tiny
ANDREWDEASON
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
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.
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Saturday, November 14th, 2020 AT 4:08 PM (Merged)

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