Quentin914runner

I have a 91 4runner v6 3.0. I replaced my thermostat checked to see if the heater core was clogged the hoses get hot and have pressure but I have no heat to very little at all. It's winter and I can't defrost my windows let alone stay warm. Any suggestions?

NickMiller

Did you "burp" the cooling system after you replaced the thermostat? Sometimes air bubbles in the coolant passages/hoses can keep coolant from flowing through the heater core causing the air not to heat up.

Quentin914runner

Yes I bless the lines a few times til there were no bubbles. Could it be the water pump? The hoses have pressure though.

NickMiller

Was the heater on full blast (including the rear if you have it) when you bled/burped the system?

I'm just trying to get all the info I can before I try and guess what's wrong

Quentin914runner

Don't have a rear heater but I am not sure if heat was on when I tried it. I will go out and try then let you k ow if that works. Lets hope so.

NickMiller

My heater hadn't worked well for years until I replaced my radiator which required a burping of the cooling system. Now it works even after a couple minutes of idling (at 35-40 degree outside temps BTW)!

I hope it works for ya!

Quentin914runner

It did not work at all. I put a new radiator in last year cause my old one had blown. Had to replace that at night in the middle of winter not fun. Now I did notice I am a little low on antifreeze but when I did have it full it still did not work properly. But maybe need to try again with heat in and burp it when full. Any other ideas in case that does not work?thank you for your help btw

NickMiller

You have to add coolant while burping... The air bubbles take up space that should be replaced with coolant while burping. I'm NOT saying this would make a difference for your heater problem, but it's something to remember in the future


Have you tried backflushing your cooling system?

This thread talks about it... https://www.yotatech.com/forums/f115...-issue-105570/

Marc

There is a valve for the heater on the firewall behind the throttle body.
Check to see if that's opening fully.