80 series hvac

[mtlandcruiser]

Did some reading and I cant find a similar thread to work off of.

1993 Lc
A/C works awesome. The heat blows very weak at 96degrees. The rear heat on floor blows 106degrees. When u switch from cold to hot on any speed it dosnt blow as hard as when it is cold. If on heat dashboard gets very hot to the touch.

 

[Pascoscout]

First off the front heat and rear heat are on completely separate systems. How the rear is working has nothing to do with the front.

If you have low air movement inspect your air box for debris, make sure your fan cage isn't damaged and make sure all of the flaps are connected to their linkage and moving like they are supposed to. Also make sure a duct has not come disconnected, if the dashboard itself is warming up that may be a cause.

 

[Pericles]

Second Pascoscout. Sounds like a duct might have come disconnected. Back in the dash, the ducts slide into one another, but don't "lock" together in any way. Could also be clogged by debris. One of those "have to get in there to find out" kind of jobs.

 

[baldilocks]

First off the front heat and rear heat are on completely separate systems. How the rear is working has nothing to do with the front.

If you have low air movement inspect your air box for debris, make sure your fan cage isn't damaged and make sure all of the flaps are connected to their linkage and moving like they are supposed to. Also make sure a duct has not come disconnected, if the dashboard itself is warming up that may be a cause.

More specifically, there is a hot water heat radiator (heater core) fir the from underneath the dash and one Uber the passenger seat for the rear. These are separate but both receive hot water from the engine through the one and only “heater valve” mounted to the firewall.

If the air flow is good with AC selected ON but not with heat selected ON, then it’s doubtful that an air duct problem exists.

Does the dash board become noticably colder with AC Selected on? It should if a duct has become separated just as you feel it does with the weaker heating selected ON. Have you put your hand up under the dash with the blower running to feel for air movement from open duct joints?

 

[Pascoscout]

If it's blowing good on cold and poor on hot sounds like the flap that mixes hot/cool air is stuck in the cold position.

 

[mtlandcruiser]

First off the front heat and rear heat are on completely separate systems. How the rear is working has nothing to do with the front.

If you have low air movement inspect your air box for debris, make sure your fan cage isn't damaged and make sure all of the flaps are connected to their linkage and moving like they are supposed to. Also make sure a duct has not come disconnected, if the dashboard itself is warming up that may be a cause.

Where is the air box

If it's blowing good on cold and poor on hot sounds like the flap that mixes hot/cool air is stuck in the cold position.

How hard is to get to?

 

[60 toy ota]

Yeah I'm thinking blender door isn't opening all three way on heat

 

[Pascoscout]

Air box is behind the glove compartment. Most of the flaps are either just down stream of the fan or can be accessed behind the stereo.