Hey guys--

I wonder what is causing this: my heater will only work normally every once in a while. Other times, I leave it on auto, and the fan doesn't turn on at all. If I manually turn on the fan, only cold air comes out. Do you think it's the heater control valve?

Thanks!

 

I see you're in NY where it's cold - in the auto mode, the heater fan will not come on until the coolant temp reaches a level where you will get warm air and not cold air.

 

Oh yeah, I know. All of this is after the engine is completely warmed up. The car's heater has been working fine here in NY for the last couple of years. It's just now that it's not working as it should.

 

Uh Huh. Sounds like the heater control valve is kaput then...

 

it's 200 bucks for a new one. it' is just a small air switch. here's how i did a quick fix on mine since it would be cold for a loooooooooong time and i could save the cash.

go under the car on the passenger side where the unit is located. unbolt the 2 screws that hold it on. REMOVE the vacume hose that controls it and by hand you can open the valve. screw it back down WITHOUT the vacume hose connected to it (so it wont close again) and ta da, your done and you can still fully regulate the climate from your control panel. come summer you can plug the vacume back up or manually move the switch back closed and ta da! cold again, and the heater core is closed off.

it takes 5 minutes to do, and saves you 200 bucks until you are ready for the expense. truthfully, since i can completely cut the heat off by regulating the climate inside, you'd never know it was open.

good luck!

 

Wait, the $200 is for the Heater Control Valve, or does anybody know where I can get one for a better price? Thanks!

 

instead of buying it just switch the two hoses on the top of the unit

 

what about topping off the fluids? Thats the exact same problem I and a alot of people had. I'd try adding fluid and making sure everything is right to full before spending $200 on that valve

 

it isnt his fluids. the heater control valve is a common problem. if you will simply disconnect the vacume line gong to it and manually open it, everything will be fine.

 

ok, i'll take your word for it

 

Topping off the fluids (even if it looks full!!!!!) costs almost nothing. Its worth trying first.

It is also a very common problem (honestly, more common than the valve failing). Don't knock it untill you try it.

Keith

 

ok, im not arguing with anyone, but the fluid that goes through his heater core is antifreeze. without antifreeze,.... well i dont even have to explain all the other troubles he would be having, but the car would have to be BONE DRY for the heater not to work, and he would have experienced other problems long before this.

i say top the fluids off anyway. then go replace the control valve, or stick it open.

 

Keith's right- the same thing happened to my 92 SC4. The only time I was getting heat was when I floored the gas. I didn't even think of checking the coolant level, and instead went through all the posts on this forum and considered messing with the valve.

But once I topped off the coolant overflow tank, all was well.

 

Keith is absolutely correct, the heater and valve are high in the coolant circuit, and an air bubble can stop coolant flow - if you get heat under hard throttle when high revs are moving more coolant, it is probably an airlock.

With the engine fully warmed up and idling (thermostat open, bottom radiator hose hot) *carefully* open the coolant tank and top up the coolant. It just might solve the problem for good...

 

This is in no way a flame, just a heads up.

The coolant level will be at the full mark and still need to be topped off. It doesn't make any sence, but it works. I had a similar problem, where the heater would only work when the car was moving, then blew cold air when I came to a stop. Not a problem in florida, but it just got annoying for the passengers in the car. I checked the coolant level, and it appeared full. The Lexus dealer told me to top off the fluids. I though he was crazy- ITS FULL already. I ended up adding....no lie..... like 4 ounces of distilled water to the already filled coolant tank. The heater has worked perfectly ever since.

I have seen about 6 or so Lexus cars with this problem my self, and I passed along the advice- and it worked every time. The Dealer told me that people bring their cars in all the time with this problem and for years, they were replacing heater parts at a great expense, but in reality just topping off the fluid saves hundreds of dollars.

Its pratically free, so why not try it first. You've got nothing to loose ...but maybe 79 cents for a gallon of distilled water or just use some leftover coolant sitting in your garage.


I'm just trying to save people some money and hassle.


Keith