No heater..

[OUMike]

Hey guys, 1994 Silverado 4.3L V6.

 

205,000 miles. I get AC just fine but zero heater. I'm thinking I need flush heater core. How would I go about this? Where is it located? What does it look li ke?

 

Thanks guys.

 

Any other possible solutions are more than welcome.

[vxaxv17]

I dont know if the heater core is the problem, but it is located under the dash, usually on the passenger side. It looks like a small radiator (fine metal fins) but you wont see that until you actually remove it from the housing. It is usually black plastic.

[ProSport Tim]

Sounds like a stuck thermostat to me.

[OUMike]

Sounds like a stuck thermostat to me.

 

<{POST_SNAPBACK}>

 

 

 

Yea, I woulda thought so too, except the truck gets to operating temp just fine, and the thermostat is actually new.

[Wingnut]

Is your coolant low?

[OUMike]

hope, everything looks good.

[Rolandd]

Several issues need to be investigated before flushing. Make sure that any heater temperature controls are working properly. On these trucks I think it is all done with the ducting in the heater box. You should be able to hear the duct doors move and should be able to hear a difference in the sound of the air coming out of the vents as air is directed from bypassing the heater core (cold) to going through the heater core (warm). Also, if you put you hand on the hoses under hood, they should be hot with 195 degree water flowing through them. If the hoses do not feel hot then the heater core is blocked or the temperature is controlled by a water valve that is stuck.

 

To flush the heater core you need to drain the radiator and then disconnect the smaller heater hoses that run from the engine block to the firewall . One hose should run to the top of the intake manifold, the other to the top of the water pump. The hose from the intake is the supply, the other is the return. For most effective flushing, run the water backwards through the heater core. I usually take a garden hose and hold it against the heater hose--this connection will create enough flow to do what you need.

 

If you flush the heater core, you should see a lot of flow through it. Sometimed a bunch of sediment can be washed away, however usually in a vehicle this old you should think about replacing the heater core as it is probably blocked solid with scale if you are getting no heat. (I have owned pleanty of cars with 20+ year old heaters that were fine, so look to other issues before replacing the heater core, which can be a big job).

[cmoore74]

I had the same problem on my 2000 S-10 with 4.3L at about 85k miles. Also I just posted the below in another topic along the same lines.

 

 

I had a 2000 S-10 P/U with the 4.3L and one day the heater wasn't blowing hot air. Turned out the heater core was clogged from the dex-cool coolant. This was at 85k miles. I was lucky and caught it early enough as a full chemical flush cured the problem. This is a very messy job so I ponied up the $ for the stealership to do the work. Cost was about $250 for the full chemical flush and refill with new fluid.

 

If you don't catch it early enough you end up replacing the heater core $$$.

 

Not saying this is it, but there are tons of complaints against dex-cool in the 4.3L motor...

 

http://www.consumeraffairs.com/automotive/gm_dexcool.html

 

http://www.automotivehelper.com/topic83185.htm

 

http://forums.hotrod.com/ubbthreads/showfl...184&an=0&page=0

[OUMike]

Several issues need to be investigated before flushing.  Make sure that any heater temperature controls are working properly.  On these trucks I think it is all done with the ducting in the heater box.  You should be able to hear the duct doors move and should be able to hear a difference in the sound of the air coming out of the vents as air is directed from bypassing the heater core (cold) to going through the heater core (warm).  Also, if you put you hand on the hoses under hood, they should be hot with 195 degree water flowing through them.  If the hoses do not feel hot then the heater core is blocked or the temperature is controlled by a water valve that is stuck.

 

To flush the heater core you need to drain the radiator and then disconnect the smaller heater hoses that run from the engine block to the firewall .  One hose should run to the top of the intake manifold, the other to the top of the water pump.  The hose from the intake is the supply, the other is the return.  For most effective flushing, run the water backwards through the heater core.  I usually take a garden hose and hold it against the heater hose--this connection will create enough flow to do what you need.

 

If you flush the heater core, you should see a lot of flow through it.  Sometimed a bunch of sediment can be washed away, however usually in a vehicle this old you should think about replacing the heater core as it is probably blocked solid with scale if you are getting no heat.  (I have owned pleanty of cars with 20+ year old heaters that were fine, so look to other issues before replacing the heater core, which can be a big job).

 

<{POST_SNAPBACK}>

 

 

 

Wow. Lots of info. Thanks!

 

Okay so backwards...so put the end of the garden hose against the end coming from the intake?

[Rolandd]

You have to look at the pump. If the heater hose is near the top radiator hose, flush from the intake hose. If the heater hose is near the bottom radiator hose, put the garder hose to the water pump hose. Also, check you thermostat by feeling the top radiator hose to make sure that it is hot. You should be able to feel as the thermostat opens because the hose will suddenly get too hot to touch.

 

If you are unsure of which heater hose is the supply, flush in both directions to make sure that you get everything loose.