No heat from heater.

[jeepgod]

So here is the deal my sister has a 89 mini 4x4 4cyl 5spd and the truck as no heat from the heater. I have checked all the normal stuff and it seams to be ok and collent seems to be making it to the heater core. I am out of ideas and I am sure that I am not the first to come across this any help would be great.

 

[liljlandon]

Check the thermostat? Does the truck reach operation temp?

 

[Jukelemon]

Sounds to me like a classic case of T Stat failure.

Are you getting any heat or just low heat?

 

[jeepgod]

The truck has a brand new t sat and gets to normal operating temp.

 

[2ndGenToyotaFan]

There is also a flapper door that diverts the air through or around the heater core. Move the hot-cold selector back and forth, you should hear a "thwump" under the pass side foot well. Have you checked to make sure that the heater valve is opening? It's on the firewall in the engine compartment.

 

[jeepgod]

Ok I think we are to something. The hot cold selecter will only go half way from cold to hot. My father just manally opened the valve on the firewall.so any guess on how to open the flap

 

[2ndGenToyotaFan]

If you pull the glovebox down you may see how to get into the heater/cooling ducts... Check the FAQ thread here, I did a thread on replacing the heater core, and it has lots of pics of the process. You should not need to get in that deep, but it'll help you figure how far you have to go.

 

[2ndGenToyotaFan]

https://forum.ih8mud.com/79-95-toyota-truck-tech/200424-84-88-89-heater-core-change.html

See post 4, I think you can get to the flapper from the second pic.

 

[raydouble]

If the heater valve wasn't open all the way, you might have an air bubble/low coolant level in the system.

Start and warm all the way up with the cap off.....add coolant as needed.

 

[2ndGenToyotaFan]

Oh, I just saw that you have an 89 mini... The heater stuff will be similar but not the same as that thread...