Heater doesn't work. It only blows cold air.

Trendkill

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I searched around other threads before I posted this and there was only one thread with the same symptoms as mine, but the person never followed up.

The details:

-Sept 2011 bought the car in AZ, my father replaced the thermostat and flushed the radiator.

The heater didn't work all winter. Then I moved to Tennessee and now I need a heater. Today I bought a heater switch or valve. The old one worked fine so I put it back on. We flushed a lot of crud out of the heater core. Then we flushed the radiator, filled up an let it warm up and topped it off.

My fiance took it on a test drive around the block and said that it blew hot ass air and then he turned the heater off then back on, after that, it was blowing cold air.

When the temperature knob is set to cold it blows really hard and cold, but when you turn it to hot, it blows at about half-strength.

If anyone has any suggestions or ideas for me, I'd be eternally grateful as I am a desert rat freezing here.

Edit: Since people keep asking what model and year it is. It's a 1999, I don't know if it's a "cx" "dx" "ex" or "lx" etc. it doesn't have any badges indicating that, however it has cruise control, power steering, power locks, power windows etc. It's a 1.6L 4 cyl.. It's teal, if that makes a difference.
 

R3dline

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heater core could be clogged
 


Trendkill

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We blasted water into the hose where the heater valve is and unhooked one of the nearby hoses and it blew a bunch of brown colored nasty chunky stuff out of it. The heat still doesn't get cold; however, after that my fiance drove it around the block and he said that the heater got hot he turned it off and the it didn't blow hot air again after that.
 

b16lewis

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sounds like the system has air in it. there is a way to bleed all the air out and it sould work fine
 


Trendkill

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sounds like the system has air in it. there is a way to bleed all the air out and it sould work fine
I saw the diagram that RonJ posted about doing that (I think that's what the diagram was for) but do I turn the heater on or leave it off and just put the heat on max heat?

How do you bleed the air from the system?
 

Trendkill

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I got information from google on how to bleed it and we did that and it didn't improve anything. My fiance is going to take the dash apart tomorrow to check the switch and heater core.
 

lethal6

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Some information might help. What is the car? Motor? Can't really help you if we don't know what it is that you are working on.
 

Trendkill

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Some information might help. What is the car? Motor? Can't really help you if we don't know what it is that you are working on.
It's a 1999 Honda Civic, there are no "dx" "ex" etc badges on it. It's a 1.6L 4 banger. Teal.
 

AlaskaB16

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Are you sure your heater cable is even hooked up? You might be moving it into heat and it's not actually moving the valve to allow hot coolant to flow through the core. Look at the input side of the coolant line and check that the valve is moving when you push the lever for heat. I've seen it happen many times. Takes 10 seconds to fix unless the cable is broken. Then it's 5 minutes to swap out. Simple. Not really much to a heat system.

What make/model/year?
 

RealRabbit

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Good possibility the Blend door is stuck. Would explain why it worked then suddenly didn't. Also why youre not feeling as much air on hot. Really common on older cars. The blend door is what directs the air either past the heat core or skips it. Also possible the electric motor that controls it, since its a 99, is out. If you take the dash apart you need to see if its moving. If it isn't see if you're getting power to it. If you aren't check the the switch, if you are the motor is bad. Also check for obstructions. Keep in mind your switch, temp control knob, isn't a simple on and off switch. Its a rheostat. Meaning its not going to be 0 or 12. Its going to be 0 to 12 and everything in between.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2
 

Trendkill

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Are you sure your heater cable is even hooked up? You might be moving it into heat and it's not actually moving the valve to allow hot coolant to flow through the core. Look at the input side of the coolant line and check that the valve is moving when you push the lever for heat. I've seen it happen many times. Takes 10 seconds to fix unless the cable is broken. Then it's 5 minutes to swap out. Simple. Not really much to a heat system.

What make/model/year?


What and where is the heater cable? I am a girl and I don't know too much about cars. My dads a mechanic and I've been a gopher since I was like 6. I know a little bit about cars But I don't know what you mean by the "heater cable". I know that today we took the hoses off of this little box that had a hose connected to each side and it had a little handle on it and a cable was attached to that and when I changed it from cold to hot it opened the lever inside of the thingy.

I know the cable isn't broken because he checked that and it worked just fine.

It's a Civic It has no "dx" "ex" "lx" badges on it. It's a 1.6L 4 banger. 1999 is the year. Teal is the color if that makes a difference.
 

Trendkill

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Good possibility the Blend door is stuck. Would explain why it worked then suddenly didn't. Also why youre not feeling as much air on hot. Really common on older cars. The blend door is what directs the air either past the heat core or skips it. Also possible the electric motor that controls it, since its a 99, is out. If you take the dash apart you need to see if its moving. If it isn't see if you're getting power to it. If you aren't check the the switch, if you are the motor is bad. Also check for obstructions. Keep in mind your switch, temp control knob, isn't a simple on and off switch. Its a rheostat. Meaning its not going to be 0 or 12. Its going to be 0 to 12 and everything in between.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

It's not it worked then suddenly didn't, it's more like it never worked, then worked once and now it won't work again.

How do I see if I am getting power to it?

Let's say this with what you just said about it being a rheostat....

It only blows cold air no matter what speed 0-12 (using your example, I don't know how many settings it has)

It only blows cool-warm air on "3" for the temperature control knob (using your example, again).

I will make sure to point him to this thread tomorrow because I am taking the Jeep which has heat and he is going to take the dash apart and try to figure it out.

I will make sure to tell him to check whatever AlaskaB16 said with the heatercablewhatever.
 

AlaskaB16

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LOL.. Heater cable. Takes 5 seconds to look at it and see if its functioning correctly. In the car as well as behind the motor on the input hose.
 

Turbo_Freak

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The cable and valve is located in the bay attached to the firewall. It's by or underneath the fuel filter. make sure it moves when you put it to heat.
 

Trendkill

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It may be. We took the heater valve off yesterday and flushed the heater core and some chunky brown stuff came out. We flushed it until it was coming out clear. Do you think it could still be clogged even if we flushed it



UPDATE: We took the lower parts of the dash off and messed around there with it. The heater core, where it comes into the car is so hot that it will burn you if you stick your hands in the back. We checked all of doors and mechanical workings are fine. We're going to try to flush the heater core one more time, right now.

Both knobs on the dash work just fine, the doors open and close right, the heater valve works. When you feel around under the dash in the center in front of the firewall, there is this black box and from feeling around my father-in-law said it's hot and it burned him.

I'm the second owner of this car, and the people said that they had it serviced at a Honda dealership in Mesa, AZ. I know which one it is, but they said (If I recall correctly, as it's been over a year) they put stop leak in the radiator. The radiator, when we took the cap off the very first time when we started working on this, had this brown gunk in it and it is the same brown gunk that was coming out of the hoses when we flushed it. Could the stop leak cause the heater core to be clogged up? We got a hose nozzle that will squirt a high pressure stream out and is tapered, we're going to try it again, flushing the heater core.

UPDATE 2: I flushed the heater core again and the radiator and filled it back up with coolant. Now my car is overheating and the heat still doesn't work. We took the lower dash off on the driver, center and passenger sides and it's just not working. My father in law said that the heater core is getting hot. SO WTF?!
 
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