I have checked the heater hoses and they were both the same temperature but they werent hot. the car was up to temp and the radiator hose was hot the heater was on full blast but was ice cold. also my ac works but it needs to be recharged idk why the heat doesnt work was like that when i got it

 

Maybe the "blend door" isn't moving when you move the temperature selector lever. Maybe the heater control valve on the heater hose is stuck in "no heat" mode. The heater control valve is a brass colored part on the one of the heater hoses that I think is supposed to open when you turn the heat on and let hot coolant into the heater core. It's there to keep the heater core cold when the a/c is on.

 

Or it could just be the heater core is plugged up with stuff, maybe with "stop leak".

 

Or, maybe you don't have a thermostat.

 

Even without a thermostat your heat would soon or later work. Are you sure when you bought it the heater core wasn't blocked off, you can just breathe on that 80s tech and it will go out. look in your passenger side floor and see if you see stains from antifreeze.

 

there are no stains on the floor and i doubt its plugged since neither one of the hoses is hot at all im thinking that whatever it is that activates the heat isnt activating the flow to the heater core since mine is an 91

 

what do you mean one of the hoses isn't hot? Do you know where the heater core is located in the engine firewall? Look and see if your rad hoses are hooked up. If so it must be your switch.

 

Nevermind i noticed you have a v6 i bet even without oil that thing dont get above 200.

 

of course i know where it is but the point is both the inlet hose and exit hose are barely even worm even though the radiator hose is super hot

 

My heat wasn't working either. I pulled the passenger side under dash cover off. The cable from the 'heat/cool' lever in the dash had fallen down with part of the lever for the blend door. It was broken. I turned the part attached to the blend door- HEAT! Problem is, you will have to open the box to replace the part. So for now, I just pull the cover to adjust for temp in the cabin. Takes two minutes.

 

If the heater core is plugged up, neither hose will get very hot because there is no flow.

 

mine is a 91 so it doesnt flow all the time just when you flip the switch i think it is whatever flips the switch that is not activating it

 

Id check the heater shutoff valve and whatever controls it first thing if the hose isn't getting hot

 

do you know what the exact name for that part is?

 

The Heater Control Valve and it is located near the firewall in line with one of the heater hoses. It's vacuum controlled, so make sure the vacuum hose is in good shape and not leaking.

 

I still have not nipped this thing in the bud yet i will try to burp the cooling system but so far still no luck. I put a new thermostat, new coolant and a new heater control valve in and no luck. i put a hose to the heater core hoses it flowed out just fine it doesn't seem blocked at all and I'm not losing coolant at all ruling out the heater core leaking.

 

Do you have vacuum like you should when the heater is on at the control valve? Is the blend door in the HVAC case moving when you turn the heater on? Are both heater hoses getting hot when you run the heater? Sounds like you might have a control head problem. Check those 3 things and let us know.

 

Start the car and unhook the return heater hose and see if there is coolant flowing. I'm not sure how the V6 routes, but the feed hose should come from the front of the intake or WP, and the return should go straight into the rad. You have to have something blocking your flow through the core.

 

i have checked the vaccum line on the heater control valve and there is absolutely no vaccum to it but is should still work right since the vaccum turns on when you have it in the full cold modeso im stumped????

 

I have a Camaro that the heat and air works perfect but there is also no vaccum . I was thinking the vaccum might close the heater core when its on full cold but idk anymore.

 

You are correct. Vacuum is applied to the heater control valve only when the temp control is set to full cold. You have now narrowed down the problem to 1 of 3 choices. 1 defective heater control valve. 2 plugged heater core. 3 temp door not moving to the heat position. I'm sure this attached diagram will help.

 

Ok thanks but I don't know what any of that means but I will look at it again and try to understand. How would I go about checking the blend door but I can hear something move every time i move the temp gauge.

 

At this point I would remove the heater control valve and test it. Use a garden hose and run water through it in the right direction. Water should flow easily without vacuum applied to it. If it passes the test. Remove the other heater hose from the engine and try to run water through the heater core with the garden hose. Run the water through in both directions. If water flows easily through both the control valve and the heater core, your problem is most likely the blend door.

 

This video may be helpful.

 

How could it be his blend door when in his first post he says his heater hoses are not hot and the rad hoses are hot? Its gotta be either the control valve or a blockage.

 

well I replaced that valve with a brand new one like 2 weeks ago the car has not been ran since then since it made no difference at all on account of it being 20 degrees. I already ran water through the heater core when i replaced the valve and it seemed to flow fine both ways. Also my hose routing is a little different on my camaro and my firebird also if I remove the radiator cap there is a ton of flow in the radiator of the camaro yet seemingly none in the firebird but again the hose are routed different so idk???????

 

Is the WP actually circulating water? You should be able to find circulation of coolant somewhere. There is a circulation problem if both your heater hoses are not hot anywhere, whether it be something blocked, a collapsed hose, WP not circulating water good, ect. I would guess the thermostat is letting the engine warm up since you say the rad hoses are both hot?

 

Ya I don't see any significant flow but the temp stays consistent on the firebird but whatever I will replace the thermostat as soon as it warms up right now its in the teens brrrrrr

 

I never said the thermostat was bad. I feel like your going about this all wrong. There obviously isn't any coolant flowing through your heater core for some reason, correct? Before I just went to throwing parts at it I would check things. I would start by checking the heater hoses. You said you replaced control valve and it made no difference, correct? Make sure both the supply, and the return heater hoses are not collapsed. If they are not, I would then bypass the control valve and put the supply hose straight to the heater core and see if you get flow that way. If the thermostat or water pump was actually bad you car would either overheat or not heat up at all, and you already said the rad hoses got hot and the temp stayed steady. IMHO I think something isn't working with the control valve, or there is a blockage in one of the heater hoses.

 

alright I will just bypass it completely Thanks man I will update once finished

 

Make sure you install the heater control valve in the right flow direction.

 

I will swap the hoses tommorrow before I remove it completely

 

Rfoster, do you have any updates??

 

Ya sorry Ive been busy wrenching on my camaro trying to fix the idle issue I'll get back under the hood by the latest friday. Big Shoutout to TunedPerformance

 

This thread saved me form a long cold ride home tonight. I've been flushing my whole system for quite some time now and never understood why I didn't have heat. I figured the heater core was clogging up quickly. However, I did notice when the car was running there is vacuum being applied to the shut-off valve. I thought that was normal and actually was thinking maybe I didn't have enough vacuum. Tonight after I started the car I pulled off the line and boom HEAT! The other issue with the cable I had too but I've since reattached that cable. It does not move very well though and I assume it isn't fully engaging. Could that be the cause of the vacuum issue? How can I fix this issue and what part are we talking about?

 

Well I am glad this thread helped someone. I have taken a break on fixing my Firebird's on account of the cold weather I just fixed my Camaro's idle. Ill probably get back out there in two weeks or something.