heat problem coolant temp issue 97 wagon

Ok I am a Newb so please a little patcience here. I am asking a question for my Father

yes i have done some reading on current posts but none seem to have answeres

My dad has a 97 taures wagon .

The car takes a really long time to get hot I mean just warm up. like 15-20 minutes. i believe the thermostat is somewhere around 190 it has been replaced recently.

His main issue is the heat . it just gets wark he cant even defrost the front windshield when it ices up and im just talking a frosting nothing thick. we have backflushed the heater core and the heathas not improved .

I have heard of using hot water it that good. does it work better ??

I am basically looking for a ton of suggestions to try to help him out so maybe we can get it done in one day.

he tells me that 1 hose is hot going into the heater core and the other one is cool. should they both be hott? I would think so.

another think concerning him is thet the temperature gauge never gets to 1/2 way it goes from about 2/5 then back down to cold then back up to 2/5 anyone know why.

I guess i am looking to answer just a few questions .after reading this what do you guys think is the best way to proceed with #1 heater core
then #2 why the temperature gauge fluctuates soo much and #3 why does it take so long to warm up. Thanks alot i hope to get a bunch of responces

The heat issue sounds like thermostat is stuck open....but hopefully some of the experts will address both problems...g'luck

check the heater hoses at the firewall, if cool suspect the water pump. A quick backflush of the heater core will determine if obstructed.

The temp guage fluctuating isn't anything to worry about. t-stat closed, engine starts to get hot; t-stat opens, the engine gets cool water from the radiator and the engines cools down a little until the t-stat closes again. This is normal.
Both hoses going to the heater core should be hot after the engine warms. Since one of them is cool, my guess would be the heater core is clogged.
The warm hose is the inlet, the cold hose is the outlet. Try disconnecting the heater core from the rest of the cooling system and backflushing it with a garden hose to clear any obstructions (can you hook up hose to your hot water heater, hot water does help). I have heard of people using CLR to clear problems. I have never used it or seen it used, so I don't know what problems CLR may cause. I was thinking about trying it in one of my cars, by using my fertilizing attachment on my garden hose hooked up to my water heater.

an anyone tell me more bout the blender door ? is it eletroni or mechanical. I am used to ones with a cable. while flushing the heater core there is good flow so i do not think it is clogged or anything. also the thermostat is new too.

whith the heater core hoses one is hot and the other is warm not cool just warm. how can i chek the blender door ??