Heat box

there's no way to diagnose it over the internet. could be right, or could be simple as the thermostat or coolant pump.
if it is the heater box (radiator i assume they mean) itmight be buried deep in the dash requiring many hours of labor. the parts cost should be available at a dealer or internet parts source, as well as salvage parts for reduced cost.

 

There might be some chance of informed guesses over the internet, especially if you describe in more detail what it is and is not doing and when, and if you supply the trouble codes (if any). See the "Codes from the heat/air conditioning system" section at the bottom of this page:

Blink (a/k/a Flash) Codes – How to. | PriusChat

 

Yeah you're talking about the heater core that's in the dash so you must have a leak or something that somebody can show you or point due or you have coolant on your floor of your car? Something or if it's not producing heat then coolant shouldn't be circulating around properly in the car could overheat and damage the engine or it may have already happened who knows generally leaks don't do too well especially when it's antifreeze or coolant for the ice engine. If there's no leak and the people who want to fix this for you tell you there's no leak and then you can start troubleshooting hoses and pumps and all of that but I have a funny feeling you must have some sort of leak no one's going to want to tear the dash out to replace the heat core in the dash unless it is leaking broken something's happening with it usually a leak usually you smell that fluid coming through your vent.

 

Maybe they could blow low pressure air through it and get what's packed in it out of it like stop leak or something I have no idea but air and or water should flow through the heater core without dumping on the ground or the floor of the car If it's not getting on the floor of the car and it's just stuffed up It may be able to be unstuffed or maybe not this is a job for somebody with a adjustable air hose compressed air a rubber fitting on the end of an air hose that can fill up the space of a heater hose so it can blow the air through it and see what comes out on the other fitting water stop leak coagulated nastiness whatever once the air blows through then water has a chance to go through and make you some heat. I can't imagine changing out a whole automobile because of no heat I can possibly because of a broken heater core that's going to require 20 hours of labor and tearing the dash out of the car then I would just regulate that car to summer use.

 

Get a little propane heater one of those infrared types The screws right on top of a bottle put it in a cup holder right where you can see it You won't need it but for about the first 10 minutes of your ride.

 

They make those for golf carts....for me, if it's that cold I'm not playing!

 

Get a 300W inverter that plugs into the cigarette socket
then get a Lasko MyHeat 200W ac heater.

Both can be purchased at Amazon …. try it for 28 days then keep or return.

 

That will likely blow the fuse for the outlet. Even if doesn't, 200 watts won't heat the whole interior enough to make much difference. Maybe if you're sitting on it ...

 

Yeah, the supplemental electric heat built into the car is 700 watts and I've never been able to tell when that's on or off (other than by watching the windshield clear a bit faster). It's a small fraction of the 5300 watts worth of heat you get from the warmed up engine coolant when the heater works.

Still, you might consider posting the trouble codes here, or any other details those various car mechanics gave you, as "just packed in" isn't really something a person seriously diagnosing a heater problem is going to say.