1998-2002 Honda Accord Heater Control Valve Failure

[YOURSxTRULYx19]

My A/C blows cold but when I turn the heater on it never warms up. Do you know what may be the problem? Thanks

[fratermus]

Informative, thanks for posting. 

[JIGGYNJIVE]

@fratermus Thanks for the comment. Glad to help!

[dishpan22]

Great explanation! My '96 Accord temperature control knob somehow just unhooked from the control valve. I'll check the lever.

Thanks for posting the video.

[danial1007]

I'm using a 94 Honda Accord and I just bought a reverse camera to be fitted in the car. How do I wire them to the reverse lights? The camera has black and red wires to be fitted to the reverse lights. Thank you.

[Zafiroo]

I have a question ...

If the Heater Control Valve is inoperable and is left open the engine tends to heat up? is that my Honda Civic 98 EX is heated and passed me from last week using the heater .. and it changed everything but .. Heater Control Valve

Thank you and good day

[JIGGYNJIVE]

@Zafiroo Thanks for commenting.

Are you asking "If the Heater Control Valve is inoperative or stuck, will that cause my engine to overheat?

The answer is no. No matter what position your heater control valve is in, the engine should not overheat. Even if the heater control valve is inoperative, it should not overheat your engine.

Overheating can be caused by thermostat, clogged radiator, bad water pump, coolant quantity.

If I didn't answer you question, please post back. Thank you!

[TrinDawg37]

I am getting low heat on my 2000 honda accord EX. I live in northeastern ohio, and it's been pretty cold up here. What do u think I should try first? New thermostat then work back from there? I got my coolant system flushed just before winter hit, late fall I believe. Suggestions?

[JIGGYNJIVE]

@TrinDawg37 Check out my other video on this topic. Make sure the engine temp is in the normal zone. First, recheck your engine coolant quantity. I would then check the line into the heater core. If the line is very warm/hot, then your thermostat is fine and you may have a clogged heater core or broken heater control valve. If its not, then it could be thermostat or maybe your water pump. Post back and let us know how it goes!

[TrinDawg37]

@JIGGYNJIVE,I checked the engine temp and it was indeed abnormal. Was running really cool. So bought a new T-Stat and that seemed to do the trick. Engine temp went back up to normal operation temp and heater is kicking out some serious heat. Nice and toasty in the car now!! Seeing as how the outside temp is in the low teens right about now, I am a VERY HAPPY CAMPER!! Thx for the words of wisdom!!

[JIGGYNJIVE]

@TrinDawg37 Great news and congrats on a job well done. I really appreciate your comments letting us know how it went.

Happy New Year!

[JIGGYNJIVE]

@TrinDawg37 Great news and congrats on a job well done. I really appreciate your comments letting us know how it went.

Happy New Year!

[JIGGYNJIVE]

@primuscav It's highly unlikely, this valve is normally closed except when the heat is on. Also if you can feel heat coming out of the vents, the valve is not stuck closed.

Typically, overheating is caused by a low coolant level, failed engine fan/belt, blocked grill, stuck thermostat, bad water pump/belt, or faulty radiator (in order of ease to inspect).

[bucktheusa]

What if the cars runs fine but immediately OVERHEATS when heater is turned on?

Temp skyrockets...wondering if it's a blocked core...

Heat does come out the vents...

[JIGGYNJIVE]

@bucktheusa On a 1998-2002 Honda Accord, the coolant that goes to the heater core is tapped off the main coolant line (there is still a large volume of fluid that goes through the engine to the radiator to sink the engine heat). A clogged heater core would have the same effect as having the heat turned off. This may not be true on other cars

Typically, overheating is caused by a low coolant level, stuck thermostat, failed engine fan/belt, blocked grill, bad water pump/belt, or faulty radiator

[heysupyaaa]

@bucktheusa check my video on the heater core swap its fun we did it in winter in the dark i think if i was you id change thermostat man i went through it all that what it sounds like to me...

[anyarag]

Hi,

I think I have the same problem just on the other spectrum, my heat is always on, even in the winter when i turn the nob all the way to cold.

In your opinion would it work the other way, where the valve gets stuck on hot?

[JIGGYNJIVE]

You've diagnosed the symptom right....the heater control valve is not turning to the "closed" position. This could be due to the same problem in this video, the push-rod/pull-rod is deformed or failed, the actuator is failed (it takes the temperature control input from the interior knob and translates it to move the pull-rod), or a problem with the climate zone system (if equipped). However, I'd bet 10:1 on the heater control valve.

[chengone2]

I have 99 accord ex 4 cyl, the there is no heat when the temperture is at max. the fan blows. Do you think that is the control valve failure?

[jbrooksby]

would this broken valve cause the ac to not work at all if it was stuck open?

[JIGGYNJIVE]

jb,

A broken HtrCore valve would typically not cause your A/C to malfunction. In fact, when you start your car first thing in the morning, you should be able to feel cold air if you have you A/C on.

I would attempt recharging the A/C with a home kit if your car uses R-134 (most made after ~1985 use R-134) found at any auto store.

If it fixes it, GREAT!

If it fixes it temporarily, take it to get the A/C leak checked (think $60)

If not, take it to a pro

Thanks for the comment! Good Luck!

[mikep95133]

Very helpful video. My AC was not cold enough and it was the arm moving around on the heater control valve. The square nylon boss was a bit worn so eventually a new valve will have to go in there. Thanks again! -Mike

[amosx]

Nevermind, I just got the part from Honda. 79710-S84-A01

[amosx]

Hi, thanks for the video. I have the same problem with my accord 02. With your video I was able to find the problem. Do you know the part number for the Valve assembly ?

[JIGGYNJIVE]

Glad it helped! I went to Advance Auto and they had the heater valve "Factory Air" p/n 74649. I used the existing bracket, hoses, and hardware on my car

Mine is a 2002 Accord EX 4-cyl.

You'll lose a little coolant when you remove the heater control valve ass'y, but i was able to tie the heater core hoses above the heater core to minimize loss. Also, I recommend getting a spare hose clamp or two in case the heater valve hoses have hardened and leak.

[amosx]

Thanks for the tips.