92 FJ80 Heat issue (rear heat works, front heat doesnt)

[Mark W]

It is not uncommon for the heater core to clog up. The front heater seems to be more prone to it than the rear. I acid flushed one a few days ago. Went from about 120* max temp measured at the dash vents running down the highway with outside temps in the 60 degree range to 220*+ with outside temps at 15* (got tired of burning my hand holding the sensor there and figured that was all I really needed to know. )
The rear heater was out doing the front significantly. Now it is lagging behind a bit, even though it is pulling air from within the cabin. I'll flush it the next time I am doing in maintenance on the rig.

Mark...

 

[Mark W]

Would like to revive this tread..

I have the same issue... flushed, but water was as clean going in as coming out.. cable to control valve in firewall is not moving...
Any suggestions what it could be further on?

""water was as clean going in as coming out" does not mean much. if the blockage would come out just from water flowing through the core... then it would not be blockage. It is hard solidified deposits that clog up the core. You have to dissolve those to clear them (dissolve and back flush with a bit of pressure ideally).

Mark...

 

[Reko]

Ok guy's,

My problem is found, not solved yet but found.

The cable to open and close the valve on the firewall is stuck. This means that the relay to open the air valves is also blocked . I removed the cable from the relay, located behind the glove box, opened the valve on firewall manually and now I have heat in front of the car.


The only thing that I have to do is to change the cable that goes from the relay to the valve.


I hope this is helpful to anyone, ans if there is anything not clear, please ask the questions!