drpdmazda

i have a 97 4runner and am having some issues with the heat. when the heat is on setting 1 or 2 it seems to be good but once it is higher than those settings it doesnt heat well at all. other than the obvious heater core or possibly blower motor is there anything else that could be causing this issue? i recently had the timing redone and had a new thermostat installed as well. the truck temperature is within the regular range once warmed up but the heat just seems to be not working. the upper radiator hose is hot to the touch but the lower is not. i have checked the coolant level and my mechanic says the blower is working fine and he doesnt think its the heater core? i am lost can anyone help?


any help will be appreciated


jason

drpdmazda

also just replaced the thermostat again under warranty to see if that was the issue but its not, the heat is very unpredictable, it at times produces excellent heat but other times even after a 20 minute warm up you can still see your breath with the heat on full?

cackalak han

Do you have enough coolant in there? Do you know if the thermostat that was installed has the OEM temp rating?

drpdmazda

when they replaced the thermostat they topped off the fluid. the theromstat is an o.e.m. replacement from the stealership as far as i know, all the parts were gotten from the local yota dealer

Conatus

Your problem is very odd. I have this same issue but have yet to replace my t-stat. I think it is stuck open. No biggie to replace. Keep us posted on what you find. My heater is totally lame and the truck takes forever to warm up.

cackalak han

So the thermostat was replaced twice recently? When the engine cools, pop off the radiator cap and see if there is fluid in there.

mjwalfredo

I think I have read that air bubbles can get in the lines and possibly the heater core thus reducing the amount of heat in the cabin. I am having the exact same problem you are btw. The heat in mine only gets luke warm at best. I parked on a hill and opened the radiator cap to try and get any bubbles out but it didn't help me. It might be worth a shot if you think you might have air trapped in the system since you have changed the thermostat.

I also checked that the controls were hooked up to the flaps in the ducting and they seemed fine. That pretty much leaves the heater core as the last possibility in my mind. I recently did a cooling system flush myself, so I am thinking maybe some of the contaminants got trapped in the heater core. Once it gets a little warmer, I am going to try to flush the heater core directly.

I hope you figure out what the problem is!

snobdds

It sounds like you have an "air bubble" in your cooling system. Just remove the radiator cap and let the engine run for a few minutes. This will allow all the air in the system to be vented.

I had the same problem in my truck. The heat would cook a turkey...when it wanted to run, then at other times just blow cold air. It took me months to figure this out. Can't take all the credit though, members of Yotatech finally pointed me in the right direction.

drpdmazda

thanks for all of the fast responses! i am going to give it a shot with taking the radiator cap off and letting the truck run, and see what happens. i made sure earlier today that the overflow and the radiator were at good levels and both checked out ok. so hopefully this will fix it

drpdmazda

ok heres what i did and it seems to have fixed it so far. i took the suggestion of taking off the radiator cap and letting it run for ten minutes, while i was doing that i took the dash apart and made sure all connections were good behind the heater controls. the hearter control panel was very loose so i tightened that back up and put everything back together. took it on a quick 5 minute ride but it seemed to be pretty hot on full blast. when i intiially parked the truck to begin the work, the temp gauge read in the middle, i was hesitant but i took the radiator cap off anyway and it didnt blow off a bunch of pressure when i opened it " hot " ? is that normal?



thanks for the help thus far everyone

jason