Poor air flow from heater (1 Viewer)

Joined
Jan 26, 2014
Messages
123
Location
Belgium
I’ve got this issue with my 96 80 series, when the heater sliding knob is in the cold position I get good air flow from the dash vents, but as soon as I put it in the hot position the air flow immediatly drops and is insufficiant to heat up the cab.


Am I right there is a door that controls the flow after the blower motor to either the heater core or the AC evaporator?
Because this got me thinking the heater core might be blocked with debris.
I removed the blower motor and vacumed whatever I could inside the heater airbox in combination with some compressed air but really no difference at all.
Anyone know what to look for? Thanks
 
Joined
Jan 5, 2017
Messages
4,060
Location
Charlotte, NC & Alexandria, VA
Yes. I answered this for someone else recently. Search my recent posts and you'll find the diagram and my answer. The AC service section of the FSM is in the Resources section. It has the heater info in it.
 
Joined
Jan 26, 2014
Messages
123
Location
Belgium
Yes. I answered this for someone else recently. Search my recent posts and you'll find the diagram and my answer. The AC service section of the FSM is in the Resources section. It has the heater info in it.
I couldn’t seem to find it. Got a link?
 
Joined
Apr 3, 2022
Messages
1
Location
New Zealand
I couldn’t seem to find it. Got a link?
 

ToyotaMatt

Factory Focus-Point Mind-Set Approach
Supporting Vendor
GOLD Star
Joined
Aug 12, 2007
Messages
22,556
Location
EAST COAST
Website
vintageteqparts.com
rat-wire-1024x668.jpg
 
Joined
Jan 26, 2014
Messages
123
Location
Belgium
Thanks.
I still cannot make up how the air flows.
If all the air flows trough the evaporator first I would think no dirt and leaves would be blocking the heater core. The evaporator is clean. Unless the evaporator is bypassed when in “Hot” mode?
 
Joined
Jan 5, 2017
Messages
4,060
Location
Charlotte, NC & Alexandria, VA
Thanks.
I still cannot make up how the air flows.
If all the air flows trough the evaporator first I would think no dirt and leaves would be blocking the heater core. The evaporator is clean. Unless the evaporator is bypassed when in “Hot” mode?
I'd bet your problem is the mix door, or its solenoid. Take a close look at the diagram and matrix of operations. Unlike the other problem, yours may be a fault in the operating logic, allowing the door to close when the heat is on and keeping the airflow from getting to the vents when the heat option is selected.

Download the A/C service section from the Resources section and go through the troubleshooting procedure. Let us know what you find.
 
Joined
Jan 26, 2014
Messages
123
Location
Belgium
I'd bet your problem is the mix door, or its solenoid. Take a close look at the diagram and matrix of operations. Unlike the other problem, yours may be a fault in the operating logic, allowing the door to close when the heat is on and keeping the airflow from getting to the vents when the heat option is selected.

Download the A/C service section from the Resources section and go through the troubleshooting procedure. Let us know what you find.
Yes now I see what you mean. As far as can see the servo motor for the mix door is behind or under the radio.
I will check the linkage operation.
 

Users who are viewing this thread

Top Bottom