Heater Question

[Festiv93]

I have a 93 festiva. When I got the car a month ago it would only blow heat out of the defrost and floor settings, and cold through the dash. Weather in Ohio has been in the single digits now for the past couple days and Ive lost heat on all settings now. The antifreeze in the radiator looks rusty. Wondering if theres too much water in it, it didnt look froze but who knows. Also wondering if it could be a stuck thermostat? Should I back flush the entire cooling system or just the heater core? Could that be plugged? And what caused me to only have heat on the defrost and floor settings before and not the dash vents? Any help would be great!

~ Sincerely
A Cold Festiva owner :nightmare:

[koRnhead]

Well first of all, festivas do NOT make heat through the dash vents....
And yes a flush is a good place to start. If the coolant is that dirty, get it out!!

[Pu241]

That is how the heater works.
No heat through dash vents.
In a properly working system it works well, even in single digits temps, once it up to temp.
You have another issue, could well be a blocked heater core.

[sc72]

Festiv93, If you are not using a two stage thermostat get one of these it should help.
Murray Plus #41492 $8.99 at ORielys
Mazzda #8AK1-15-171-9v $18-20 IIRC
While you have the car down follow this procedure recommended by FB71
click on the repair help forum,
click the top sticky--Nice tidbit for those with barely any heat, read the whole thing or skip to page 12, post #117 by FB71 Follow what he is teaching it takes some time but it works. Good luck

[Prafeston]

Did you lose heat in the defrost/floor vents? Or did it stop blowing entirely?

[Festiv93]

It still blows air out of all places, just not heat anymore

[Prafeston]

Ok...just wanted to double check cause my blower motor keeps quitting on me. And that was an easy fix...just hit it a few times with a hammer!

[rmoltis]

If its the cold weather causing the problems. I got a 195 degree thermostat. And on cold days recently its been 3-7 degrees and on warm-up during idle it will peak around 140-165 degrees and once I start driving the windchill drops the coolant temp to a steady 128 degrees which is enough to blow warm air into the cabin as long as its on recirculate. When the heat is venting cold air into the cabin from outside over the heater core it continuously cools the coolant temp. But on recirculate the air heats the cabin and the warm air is recirculated over the heater core helping raise the coolant temperature instead of dropping it. Those are the best 2 things you can do to keep your car warm in the cold weather. My scanguage II shows me the air intake temps under the hood as well as the coolant temps in real time. And these two things have worked the best for me over the years. My 195 degree thermostat only pops open at 195 everytime based on the temp readings on my scanguage II. And only on warm days will it actually even get there and that's only if I'm not moving to rush air over the radiator. These b3 engines don't put out much heat to pop the high temp thermostat so keeping all the heat in the block helps considerably the fan also kicks on at 200 degrees for my car.

[bravekozak]

Read this thread. If you don't have air conditioning, then the fins on your heater core are probably plugged up.