Hi I have a 1992 camaro rs with a 305 engine and when I turn on the heater nothing but cold air is blown out. Also when I turn on the defroster and put that on warm it is still cold air. It seems as the blower works well. What can this be? I was thinking it was my heater core but then I was told that it might be my thermostat or something else stoping the hot air. So before I went out and changed the heater core I wanted to ask all of you want it might be. Thanks any help would be great.

 

This happened to me a few weeks ago, I would try to use the heater (because its crazy cold here) and nothing but cool air came out. Even when operating at normal temps. But a week later I found a puddle of green coolant on my passanger floor mat and I realized that it was my heater core. and I am in the process of fixing it now and it is a PITA!

 

I just installed an amp in my car over the weekend and I did notice that under my floor mats on the passenger side it was a little damp and I was not sure what that was from. I just went out and checked to see if it was wet and it was still a little damp. So I know that if it is my heater core that is leaking I need to replace it but how can I be sure that that is what is causing the dampness under the mats. If i drove with the heater turned on for a while would that cause it to leak right away, so I would be able to know for sure that its leaking? Also I first thought the dampness was from the rain because I do have leaks in my car and it did ain about a week ago. Thanks for your help.

 

Ok. The dampness might be from the leaking t-tops. Drive around with the heat on and check if it is coolant, it took mine up to a week before i noticed a huge puddle on the floor. Also try smelling it, if it has that sweet smell to it then it maybe coolant. I would keep checking for it tho and you should not rule out a bad core. Another thing is that maybe the slide to change the heat is not opening the door for the heater? Which would cause the heat to not circulate through the vents.

 

I wouldnt think its the heater core or the thermostat. Are you overheating or losing any coolant? Is the engine getting to operating temp? If all is fine, I would make sure that the heater door is opening. You should be able to tell by sliding the hot/cold slider back and forth a few times. If its opening, the other thing it could be is the diverter valve under the hood is not letting coolant go to the heater core. Make sure that the vacuum line is hooked up to it and its getting vacuum when the heat is on. If ok, then its probably a bad diverter valve. Mine went bad a while ago and I had cold air coming out of the vents and after about 30 min. or so, I would start to get heat. I replaced the diverter valve and now I get heat when I turn it on.

 

I have a 92 also and I live by you so mabey you could come by and I can take a look at it my car had the same problem.

 

My kid came home the other day and told me that there was no hot air coming out of the vents on his 94 Toyota 4Runner. When I met him outside I noted a little steam coming from the engine compartment. Well no kidding he didn't have hot air, he had no hot water. The radiator was COMPLETELY dry, except for what was blowing out as steam. My point is, make sure your radiator is full. That dampness really sounds like a heater core gone south. Do you have a kind of slick film on your windshield every morning? The kind that doesn't just wipe off with a cloth, but just kind of smears? Thats what antifreeze does when it's blown through the defroster.

 

If your core is good, odds are like said above, a stuck thermostat.

 

stuck tstat or faulty heater control valve.

 

I've actually got the same issue going on with my 92 305 rs. New t-stat, new water pump, new radiator hoses and new radiator. Ive removed the heater control valve thinking this was the issue (rear intake manifold to heater core, heater core to radiator). Previous owner had removed the thermostat and hard wired the fan to run all the time. I've installed a new cooling fan switch and re-wired the fan correctly. Idling in neutral, the car will warm up fans kick on car cools down and I've got heat. Problem is as I drive down the road, temps drop and I've got no heat. Cooling system hasn't lost any coolant as when I check the radiator and overflow cold the levels aren't changing. Both hoses going to the heater core are hot so I'm not thinking the heater core is clogged. Any other ideas that I'm overlooking? Thanks

 

i agree - its the heater core, they always rust out. if it was the control valve that was going - well that is under the hood on the manifold and nowhere near the floor.
buy a new heater core. buy two - they will not be available for long.

 

he said his temp is normal so its not a thermostat sticking problem, check ur coolant level, usually no heat is caused by low coolant.

 

i gotta has a point. it may be no coolant getting to the heater, but look at the valve. its plastic with a t and a wire connected to it and if your a tbi it sits just behind the theromstat and under the air cleaner. if its a problem there will be green fluid all over the manifold.
if that is not it then its THE HEATER. sorry, i mean its THE HEATER. did i say heater, what i really mean is, ITS THE HEATER.
when you dont get heat, and the passenger floor is damp, its THE HEATER.
the core rusts out and it leaks.
i bet you dont get hot air when you turn on the defroster either. do you know why? ITS THE HEATER.
i dont know about you but i just had fun.
Merry Christmas and welcome to the world of f-bodies. and you are up north which means you really need the heater.
so do yourself a favor and go out and get a new heater core.

 

Ok this weekend I drove around with the heater on the whole time and it was still blowing nothing but cold air. I checked the floor last night and the floor was dry. So the heater is not leaking anything. I checked the coolant level and that is full. I tried to listen to see if I could hear if the door thing on the heater opened when I turned it to hot but I could not tell if it was opening or not. Thanx for everyones help. And what is the next thingthat I shoud check? thanx again

 

ok so I was messing around with the heater control valve and I noticed that the vacuum line does have suction. So i decided that I would try the heat with the vacuum line off and it worked I got heat in the car!! So what does that mean now? Does it mean that I have a bad control valve or is it something else?

 

I would make sure that the heater hoses are connected to the right ports on the valve. Try switching the 2 hoses and hook the vacuum line back up and try the heater.

 

I just checked the hoses and they are all connected to where they should be. What does this tell me now?

 

anyone have any ideas of what it means when the heater doesn't work when the vacuum line is connected to the heater control valve? the heater and the defroster only blow hot when I disconnect the vacuum line. Does it mean the control valve is bad?

 

Ok, I need help......... I replaced the heater control valve and plugged the vacuum line back to it and now there is no heat!! So can anyone tell me what is going on? When the vacuum line is not connected to the heater control valve then my heater works great and blows hot air, but when the vacuum line is connected the heater blows out cold air. Please help, thanks

 

the heater control valve is designed to blockoff the flow of coolant to the heater core when the AC is on(so the AC doesn't work as hard to cool off the hot heater core) You should only have vacuum at the hose when the AC is on not when the heat is on.