Hey good people , 75 Mav. 6 cyl. No heat or defrost , fans work fine in all positions on switch.. Anitfreeze levels fine , all hoses hot including both hoses to heater core.. No heat at all , could this just be thermostat or am I looking forward to heater core replacement ?? Could heater core be blocked up , any way to test heater core if blocked ?? Help please.. Thank you Ps previous owner did not drive in winter and cant tell me if there was any last winter..
if the hose going to the heater core is hot and the one coming out of it is hot and you don't have a leak I would think the heater core is ok. Could it be the blower motor?
Could be one of the doors on the heater box is stuck shut.Does the car have A/C?? If so...Heat valve on the heater hose (under the hood may be malfunctioning)Or the valve isnt recieving a vacuum signal. Or vacuum signal isnt reaching the controller on the dash or the controller isnt functioning anymore. If not an A/C car then pugged heater core or door on box as stated above or a cable came loose on the controller. Or no coolant flow...usually means water pump has rusted impeller blades. (this is all provided you have no overheating or bad thermostat condition)
I would think if it was the heat valve on the heater hose then the heater hoses wouldn't be hot, he is saying they are. I think the door being stuck makes a lotta sense. check that you.
Gonna replace thermostat tommorrow ,no AC , Yes both hoses from core are hot.. rad just replaced , no leaks , all switch positions seem intact and can here things moving when adjusting controls.. I am hoping simple thermostat , will keep posted .. Thanx alot..
Before you pull the T stat... Pull the heater hoses off the engine and run water from a garden hose through them.If it goes in one but wont come out the other...Core is plugged. If that checks good...hook em back up,top off the system and burp it to get the air out (hey..you may have an air lock problem) Now with the car running and the rad cap off...pinch the top hose shut for 15 seconds and release it.If the coolant in the radiator flowes rapidly,the pump is fine...If no real change is noticed,pump impellers are rotted off. After doing this,you can pull the T stat and see whats up with it.This car does not overheat right???
No does not overheat ... Ran on Highway 45 mins , 70 mph.. I dont have a manual , where do I look to see if the door is opening to allow hot air into blower , blower works fine , can I open it manually.. No coolant leaks , No ac , but there seems to be a valve conected to one of the heater core hoses , does this have to be opened ?? I assumed it was for bleeding.. Will I lose lots of coolant if I disconect the core hoses to try the water flush of the core ?? Appreciate all help , new to this game and eager to do it myself..
In case this is an air bubble in the cooling system , could someone be kind enough to direct me to a quick burping proceedure ?? I dont know where to start to bleed this.. Thanx for your patence , I have searched bleeding and burping to no avail , would like to solve this before back surgery on the 5th..
when you take the heater hoses off make sure the...heater control valve...is opening all the way. flushing the hoses is a good idea to do anyway. run water through them both ways (each hose). the...core/HC valve...could be opening just enough to let water through and get both hoses hot... ...Frank...:Handshake
odds are that the blend door is not working. stick you head under the dash on the passenger side and look up you should see a metal L shaped lever sticking out the side of the black box up there (use a light). now note the postion of the lever. now move the heat selection lever to the other end of its slide. now look at the lever. has it moved. if its moved the problem is in the heater box, the heater core or the heater hoses. if it doesnt move then there is a controle cable that goes from the lever to the lever on the dash. check to see that both ends are attached. that should encompass the whole problem
You will lose about as much coolant as if you pop the T stat out.If you dont want to loose the coolant...Drain some out first into a clean container.This valve? Is it plastic with a screw on cap?? If so thats a poor mans cooling system flush hook up.If its at the fire wall on the top hose...Thats the heat controll valve (found on A/C cars)Make sure its opened up.Then see if you have heat. To purge air from the system: Turn heater on...Remove Rad cap...start car and let it run up to temp.T stat will open once hot and flow coolant on the ground or level in rad will drop(after rad pukes level will drop also).Add coolant if level drops.(you want enough to just cover the core tubes)Dont top it off.Let it run...T stat will open again and level will drop or you will get air bubbles in rad.Wait till air bubbles stop appering,(this may take several cycles of the T stat opening and closing)Top off rad and install cap.See if you have heat now...You can also run it and unscrew the cap off the poor mans flush hook up.Same proceedure as above but messier.
Well guys , blend door is working fine , lever is moving in all directions and I can hear it opening and closing.. As are all other levers.. Thanx kindly.. Yes it appears that I have the poor mans flush cap , when I unscrewed it there is coolant in it..There is a washer in there .. Color looked good of coolant.. If I run it with the cap off and see flow when it is warm does that rule out the thermstat ?? Cant do the flush till daylight , but t doesnt hurt to get familiar with the old beast.. Much appreciated, Thanx all..
running it with the cap off will only make a mess. take the hoses that goto the heater off at the intake and water pump. you will not loose much. try seeing if a garden hose will push water through the heater hose. if it does then you probly have something blocking the air flow accross the heater core.
Heres the scoop , Now that it is colder out there is a little heat coming through and heating the cab , very little.. Heres what got me worried, I ran it for 30 mins , rad cap off .. no visible flow in rad , just minimal swirling , very little , did not get hot enough to overflow , coolant hot but not scalding , all hoses warm and more pliable then when cold.. Put cap on and ran it around the block ,I then took the rad cap off without even a Hiss ?? Coolant hot but not scalding.. Thermostat or water pump ?? Will replace tstat in morning after flushing heater core.. Will to much water pressure blow out the core , or the more the merrier ?? All vent doors and levers seem to be working , could not find heater control valve on any hose , just poor mans flush valve ?? Cant think of anything else and confounded for sure.. Havin fun though.. Will driving the Moose this way blow her up ??
