An idea on improving the XJ's heat

[carves]

The heater in my 200 dollar XJ is stupid hot! Even when its on low it drives me to crack a window. I would recommend checking the blend door.

This ... :thumbup:

...and if its not that ... double check the heater, coolant circulation.

X 2 on a bit of sheeting in front of the rad if nescessary for a quicker warmup.

Failing that ... buy some thicker socks ... makes a lot more sense than messing with what appears to be a perfectly good cooling system ...

...and unless you have the wrong fanclutch ... theres very liitle dragging of air into the engine bay by the thermal fanclutch ... until the coil spring on the front of it reacts to an air temp of about 160*/170*.

 

[Jeepguy03]

This ... :thumbup:

...and if its not that ... double check the heater, coolant circulation.

X 2 on a bit of sheeting in front of the rad if nescessary for a quicker warmup.

Failing that ... buy some thicker socks ... makes a lot more sense than messing with what appears to be a perfectly good cooling system ...

...and unless you have the wrong fanclutch ... theres very liitle dragging of air into the engine bay by the thermal fanclutch ... until the coil spring on the front of it reacts to an air temp of about 160*/170*.

I've noticed this, haha. With the mechanical fan removed the jeep still warms up about the same. A tad bit quicker, but since I am in motion for most of my commute (back roads) it doesn't make too much of a difference.

How can I check the blend door without ripping the dash apart? If I change the temperature nob all the way to cold and then back to hot I can definitely notice a change in the temperature of the air coming from the vents.

 

[Wallyman]

210 degrees ought to make the heater work great. Or are you referring to needing more heat as far as operating temp?
Being in north TX i dont see too much cold weather so the cardboard trick works great. My aftermarket bumper/ brush guard holds it with ease so i dont have to slip the cardboard under the hood. I picked that up from when i was on the road with my dad who was an OTR truck driver. My temp even with the correct thermostat still sits just below the straight up line on the temp gauge. That may be the inaccuracy of the gauge though, who knows. it still gets the cab way past warm. the heaters in the XJs seem to be one of the finer points IMHO.

 

[carves]

I've noticed this, haha. With the mechanical fan removed the jeep still warms up about the same. A tad bit quicker, but since I am in motion for most of my commute (back roads) it doesn't make too much of a difference.

Yep, they just loaf along at a small percentage of the engine revs until airflow temp at the back of the rad dictates they need to engage fully ... at about 70% of the engine revs.

Its why I smile at the removal of them to get massive, horsepower gains ... That faerie tale is more applicable to fixed fans and the older style fanclutches that had a constant, fixed rotation speed - from startup.

How can I check the blend door without ripping the dash apart? If I change the temperature nob all the way to cold and then back to hot I can definitely notice a change in the temperature of the air coming from the vents.

The general indicator is when the air coming out of the vents ... isnt hot enough ...

Mine stills gives a little thump sound when its fully in position ... and blocking the cold airflow ... any noise from yours ??

Other thing that might work is disconnecting the actuator and moving the lever by hand ... gently ... and see if that sheds any light on the problem ??

 

[Jeepguy03]

Yep, they just loaf along at a small percentage of the engine revs until airflow temp at the back of the rad dictates they need to engage fully ... at about 70% of the engine revs.

Its why I smile at the removal of them to get massive, horsepower gains ... That faerie tale is more applicable to fixed fans and the older style fanclutches that had a constant, fixed rotation speed - from startup.





The general indicator is when the air coming out of the vents ... isnt hot enough ...

Mine stills gives a little thump sound when its fully in position ... and blocking the cold airflow ... any noise from yours ??

Other thing that might work is disconnecting the actuator and moving the lever by hand ... gently ... and see if that sheds any light on the problem ??

I don't notice a thump sound when fully in position, but then again I've never really listened for it. My XJ makes MANY noises. I guess my question is how do I manually test the blend door? I'm guessing its somewhere behind the dash on the passenger side but I wouldn't know where to look for it. I'm more familiar with the outside of the XJ than I am the interior. :laugh3:

 

[techno1154]

How can I check the blend door without ripping the dash apart? If I change the temperature nob all the way to cold and then back to hot I can definitely notice a change in the temperature of the air coming from the vents.

The cooling/heating system on the XJ have three doors. The one in the passenger foot well is (the only one that is) cable operated. That one selects between fresh air as in air from outside the vehicle and re-cerculate air. That one would not be a problem unless the cable is broken.

The other two are vacumn operated and are located on/in the air box and can be seen under the center of the dash on the driver side. I checked mine by lying on my back and using a light. It will be good to be skinny or have a high level of dexterity,..or you could remove the knee blocker. These doors controlthe heat,....hot, cold, warm (one door) and the vent through which the air exits,...legs, face, defrost etc. These doors each have multi vacumn controlers that moves them from open to close and mid way between depending on the setting on the dash controler. The spaghetti like vacumn hoses between the controler and the doors are a ????? On my XJ, the dash controler was not working properly as in had a leak on one port and there are many ports that did not allow one door to position properly. I simply unpluged that hose and pluged the controler port. This kept things working good enough for me to be happi/er.

Unfortunately, I did this when working in Iowa in the winter of 2007 so I do not remember exactly what/which hose or door it was. I do not have my CD workshop manual with me so I am not too much help here.

What I am trying to say here is, if the engine temperature is good, the heater core is good, for the early XJs the vacumn valve in the engine compartmentis operating and the cab air is cold, it may be time to get under the dash to see if the doors are operating properly. Some one with a manual handy could help with the doors and hoses layout.

 

[Jeepguy03]

So it is on the driver's side under the dash? I ran wires through there for my KC lights so I will have a look under there and see what I can find.

 

[McQue]

Blend door is inside the HVAC housing in between the Heater Core and the Evaporator Coil according to my FSM.

 

[Jeepguy03]

Blend door is inside the HVAC housing in between the Heater Core and the Evaporator Coil according to my FSM.

Ohh... that doesn't sound fun to get to. :scared: I'll try flushing the heater core first. Should be a little warmer tomorrow so I'll try it after work.

 

[McQue]

http://naxja.org/forum/showthread.php?t=1014264&highlight=blend+door

this thread sheds some light on the subject...