This will be my first winter in my t4r. In my car (Mazda 626), you won't be able to get any heat out of the vents until it's at operating temperature. I've noticed in my 4runner, I can get heat even when the temp gauge is all the way at cold.

Is this unusual? Can you guys get heat when the temp is really low? Maybe some dick took the thermostat out? Am I just over reacting?

the heater is dependant on your engine coolant being warm/hot. when you first start your car the blower will blow but only cold air until the engine can warm the coolant that is running through the heater core.
if your thermostat is removed your heater will still work but it will take longer for the engine to warm up, because the thermostat controls minimum temperature. meaning it keeps the coolant circulating in the engine until it has reached it's minimum temperature (about 190) then it will open and allow the circulating coolant to enter the radiator.
the radiator will then do it's job with the help of the cooling fan and control maximum temperature.
the radiator and heater core are both water to air heat transfer devices, air blows across the radiator and picks up the heat from the cooling fins and takes it away from the engine, air blows across the heater core and does the same thing. picks up the heat and carries it away, but the path away from the heater core is the vent that blows on your face. so that warm air is then transferred to your cold face and heat is exchanged.

I hope this could answer your question.

and yes. my heater will blow warm air when it's just at the bottom line.

Right, I'm saying that if there is no thermostat installed, I'd get heat as soon as the coolant started warming up. In my car, I don't get heat until the thermostat opens and warms up the heater core. I get heat way before the temp that I assume the thermostat would open up at, so I'm concerned that there is no thermostat, so the heater core is circulating before operating temp. Am I wrong?

You've got it backwards. If there was no thermostat, the coolant would flow into the radiator, causing it to cool off. It would take much longer to heat up. Because you do have heat before it reaches a temperature hot enough to open the thermostat, the heat remains in the heater lines, which is why you get heat faster through the vents.

And for the records, mine heats up quickly too. It's just a nice perk of some good engineering.

If it's producing heat when the slider is all the way to 'cold', then the cable to the little heater valve on the firewall is maladjusted, or the valve is kaput.
The engine T-stat is there to warm the engine up faster by keeping all the coolant in the engine until warm up, after which it opens and allows coolant to go through the radiator.
As for how fast heat becomes available, it depends on how cold the ambient temp is. It should start getting heat within a minute or so when it's cool, longer when it's very cold.

My wife has a mazda 3. Same thing. I've always attributed it to the difference in engine size. Truck engine vs tiny sedan engine. I've actually noticed a difference in the a/c, too, which i also attribute to bigger hardware under the hood.

the heater core is in the loop with the engine. so as your engine is still warming up but still before the thermostat is open will produce a small amount of heat and gradually get warmer the longer it runs.

a good way to tell if your thermostat is removed is from a cold start open the hood and feel the upper and lower radiator hoses. at first they will both be cold as the engine warms up you will notice one will be cold but the other will be getting warmer, there will be a significant difference in temperature before the thermostat opens and once it does they will both be hot.

If the thermostat is not there it will be more like they will both start out cold, and as one warms up so will the other. they will stay pretty much the same till the point where the radiator is cooling it off.

Pluton - The slider thing is on heat, my concern is just about heat coming out when the engine is cold.

Bishop - I'll try that test if I have another panic attack haha

Brique - (insert sexual joke about bigger hardware under the hood here)

This.

The heater lines run from the back of the motor, to the heater valve, into the heater core, then back into the engine.



The fact that your heat gets warm before the engine "temp" is warm, is nothing.

The thermostat essentially keeps the motor "warm" until it hits the required temp to open the thermostat.

By doing this, they are essentially "blocking" the motor off from the radiator, causing the block and heater core to warm up before the temp gauge goes up.

It's not going to take long for that motor, with all the friction, to heat up the coolant in there. Then, it reaches operating temp and the thermostat opens.

one thing that might be throwing you off is coolant temp sensor locations. some car makes put the sensor on the radiator side of the thermostat and some put them on the engine side of the thermostat.

if it's on the engine side looking at the temp gauge you will see the engine warm up in a steady rate until it reaches operating temperature.
if it's on the radiator side you will see a very very slight rise on the temp gauge until right at the point where the thermostat opens and it will go to about the middle and hold.

your case of your toyota vs your mazda could be temp sensor location making it seem different

I am facing exactly same problem with my JDM 1998 Toyota Surf with 1KZ-TE motor. Could you guide me is this possible to fix this with DIY job?

Waiting for a reply.

What you describe is a function of the gauge on the dash, not your thermostat. The Toyota temp gauge probably just doesn't move until the coolant is hot enough to put out some hot air.

I only wish I had your problem. There is absolutely no heat coming out of my heater core, at all, in the winter time now. Out here in Montana, we are currently experiencing sub double digit temps as highs. I drive 3.7 miles to get back home from work. I even start my runner 10 minutes before I leave work to go home, but the heat never comes out through the heater core. I suppose all I need to do is replace the core or flush it by removing the heater hoses and flush it from both directions. I know the thermostat works fine, because I replaced it last year to to troubleshoot the problem, but to no avail.

Disregard so far: I back-flushed it today with water and then let 5% distilled vinegar sit inside it for two hours. It seems to have helped drastically. Heater is working well now.