No Heat for heater

Tiny
MAGNOGREATO
  • 1998 HONDA ACCORD
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 112,000 MILES

My 1998 Honda Accord LX is putting out next to nothing in heat. The temperature gauge is reading upscale, indicating heat, but heat control is all the way up and blows out no 'hot' air which may be the heater/temperature control may be bad(?) How to verify that or where should I look?

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Monday, December 13th, 2010 AT 9:34 PM

25 Replies

Tiny
CARADIODOC
  • EXPERT
  • 27,690 POSTS

Feel the two small heater hoses under the hood. They should be too hot to hold onto for very long. If they are cool, suspect a plugged heater core. They can usually be back flushed with a garden hose.

Here is a guide that can help fix the problem

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

caradiodoc

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Monday, December 13th, 2010 AT 9:41 PM
Tiny
RASMATAZ
  • MEMBER

Check and test the thermostat, heater core if its clogged, heater control valve and the air blend door/actuator.

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Monday, December 13th, 2010 AT 9:41 PM
Tiny
CARADIODOC
  • EXPERT
  • 27,690 POSTS

Feel the two small heater hoses under the hood. They should be too hot to hold onto for very long. If they are cool, suspect a plugged heater core.

Do you have a temperature gauge on the dash? If so, is it reading in the "normal" range. If it is low, suspect the thermostat is stuck open. You are going to have to go out and feel the hoses.

Caradiodoc

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Monday, December 13th, 2010 AT 9:50 PM
Tiny
MAGNOGREATO
  • MEMBER

Gauge is normal. Okay I got the point about the hoses. What is an air blend door/actuator and how do I know if I have got one anyway? Are they on a 1998? I can back wash the heater but if it is the front panel control how do I access it without messing up the dash?
Thank

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Tuesday, December 14th, 2010 AT 12:02 AM
Tiny
CARADIODOC
  • EXPERT
  • 27,690 POSTS

The blend door selects between heated and non-heated air for the desired temperature of the incoming air. The actuator depends on the type of control system you have. If you have the common sense manual levers, k n obs, and switches, there will be cables that could become disconnected or out of adjustment. If you have computer controls, the actuators are usually electric motors with position sensors. Either system could use vacuum motors to move the various doors around, but those are typically used for things that are turned either fully on or fully off. A door to the defroster would be fully open to defrost the windshield, or be fully off when you want toasty feet. Blend doors aren't usually set for full hot or full cold all of the time so vacuum motors don't work well for that function.

If you have a manual slide lever for temperature, you might be able to hear the blend door hitting its stops when you move it back and forth. Some cables, such as on Dodge Caravans, are self-adjusting by means of the cable sliding through fingers of a clip on the actuator lever. If the door becomes rusted tight in the cold position during the summer, it won't move in the winter, but the cable will slide giving the impression the door is working. When that happens, you won't hear the door move when you slide the lever back and forth.

If you have vacuum controls, you should be able to hear some of the doors moving when you switch to different functions, and you will often hear something moving around when you stop the engine and vacuum goes away. The systems are spring-loaded to go to the defrost position when there's no vacuum to insure the windshield can be cleared. When none of these controls work, a leak in the vacuum hose can be suspected, or the hose could be disconnected.

Computer controls often have self test / calibration procedures that can get pretty complicated. Problems with these controllers often leads to flashing display lights or the system is dead and has no lights turned on. It's common for them to be intermittent too. If you get hot air sometimes and not others, suspect the computer. Otherwise they typically do not go out of calibration unless the battery was disconnected or run dead.

The two most important clues are whether the two heater hoses are hot and if you can hear something moving when you adjust the temperature control. Beyond that, it becomes a process of eliminating all other possible causes before condemning the computer. Most manual controls can be accessed under the dash or often by removing the glove box liner, radio, or heater controls. Computer controlled actuators typically require removing the steering column and dash assembly to remove the heater box. That gets real involved and is definitely not a do-it-yourselfer project. Experienced mechanics know how to diagnose the most likely cause of the problem before removing anything, and they know what to look for when they get the heater box on the workbench.

Caradiodoc

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Tuesday, December 14th, 2010 AT 12:37 AM
Tiny
DDDROCKYCOMCASTNET
  • 1997 HONDA ACCORD
  • 2.2L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 137,000 MILES
  • MERGED

No heat on either heater hose, new thermostat, heater valve on hose new, flushed heater core good, new heater hoses, heater valve open, no carbon detected from radiator, no water in oil, no smoke, new anti freeze why is heater hoses feel like nothing in thew no flow, no heat temp gage reads normal. Originaly heater hose sprung bad leak that goes from engine to heater valve. Heat worked great previous to leak car only started to overheat when to much water and antifreeze leaked then refilled with water ran cool until water and anti freeze ran low again then did all the work no heat after changed hoses then changed everything else no heat in hoses or car?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
TY ANDERSON
  • EXPERT
  • 705 POSTS
  • MERGED

If you rev the engine when the engine is warmed up do you feel any heat by touching the heater hoses. Press on the throttle plate under the hood while feeling the heater hoses. What your describing is air in the cooling system.
Water transfers heat extremely well but air does not. Air in the cooling system can also cause overheating but not always. When the engine is cooled down enough check the coolant level inside the radiator and reservoir.
If there is enough coolant and no air in the system that tells me there is a restriction in the heater core.
Your thermostat could be stuck open allowing coolant to circulate over cooling the engine dropping the temperature to so that is feels luke warm
It could be the water pump is no longer pumping coolant but is accompanied with overheating.
My bet is air in the cooling system or the thermostat is stuck open.

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JAMES GREENE
  • 1999 HONDA ACCORD
  • MERGED

Heater problem
1999 Honda Accord 4 cyl Two Wheel Drive Manual 191000 miles

I press the air button on dash no air no light
I press the heater button ---no heat no light

I was told --a rister proble? If it is that then why no heat or air even though the blower blows?

Any suggestions? Second submission

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JACK42
  • MEMBER
  • MERGED

So basically nothing on the climate controller works except the blower control? Have you checked all fuses with a test light? Did this happen all of the sudden or has it been intermittent until now?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JAMES GREENE
  • MEMBER
  • MERGED

It is my sons car-he said the air heat sometimes did not work but now it happened all of a sudden.

What location should I check the fuses ?
Under the hood? The drivers side of the dash or the passenger side of the dash?

Thanks for replying--

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JACK42
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  • MERGED

So it has been going away, and has now quit.I would check every fuse with a test light. Sometimes part of the HVAC system will be fused under the hood as well as in the interior. It sounds liekit may have an issue with the blend door, ifit isnt doing what you request temp wise

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JAMES GREENE
  • MEMBER
  • MERGED

The lights to indicate the air is on / the heat is on/ etc do not come on on the dash control when I press them--? I will check the fuses again tomorrow

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
2CARPROS LINSEY
  • MEMBER
  • MERGED

How did the fuses look?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JAMES GREENE
  • MEMBER
  • MERGED

Okay

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
RICIAN BLAST
  • 1999 HONDA ACCORDHONDA ACCORD
  • MERGED

The car is a 1999 Honda Accord LX with 128,000 miles.

It was involved in a front-end accident. Car was repaired but when I got it back the heat was stuck ON all the time. I could turn the heat control but it did not affect the heat. The blower fan is controllable and working fine.

The next day I could turn the heat off. But once I did it now will not go back on. The radio is also not working, it won't even turn on. Seems that my clock light also does not work.

I checked all fuses and they appear to be fine. I'm wondering if it is possible that in the accident a wiring harness became detatched from its source (I pulled the center panel and the wires to the heater control knob were attached and intact.

On a side note, a soda that was in the car flew forward and drenched the dashboard, but I find it unlikely that the soda crept into the panel and did any damage.

Any thoughts?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
BRUCE HUNT
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  • 3,758 POSTS
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I say this so much that I make myself sick, but this sounds like a ground that was left off or is loose or has a bad connection. Is the heat control knob striped?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
JACK42
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Did you check all I listed in your other post with a test light?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
RICIAN BLAST
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  • MERGED

[quote="Bruce Hunt"]I say this so much that I make myself sick, but this sounds like a ground that was left off or is loose or has a bad connection. Is the heat control knob striped?[/Quote]

no, the knob "feels" fine. On the back of the center control panel it looks like everything is well connected.

Could I possibly trace the wire harness back to some other spot and maybe find it is detatched from its source?

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
BRUCE HUNT
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  • 3,758 POSTS
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Still check the grounds. The A/C works? The heat on and off controls the valve that opens the coolant. Obviously there is a problem with the valve regulation and this could be ground or a loose connection.

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Thursday, December 22nd, 2016 AT 4:22 PM
Tiny
AEROCHIC65
  • 1995 HONDA ACCORD
  • MERGED

Engine Cooling problem
1995 Honda Accord 4 cyl Front Wheel Drive Automatic 143.26 miles

purchased 9/07 radiator flushed 10/07. Never had problem til 9/09 running hot heater helped but changeds thermpostat, still ran hot. But usable. Added less than 1/8 powdered stop leak. Ran but still hotter than norm. Then lower hose blew. Drove 6 blocks@ redline. Replaced hose, now no heat. Garage says someone had dumped alot of "bars leak" in there and its likely plugging system. Wont garuntee a flush wont make it push into heater core or water pump. The engine looks like rust is sprayed all over it. It had to be done before I got it but why after all this time. What should I do. I am limited on funds and need a car. And heat too its cold out threre!HELP!

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Thursday, December 22nd, 2016 AT 4:22 PM

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