[Daladim]

I removed the ventilation system over the weekend to clean out the debris and get it working better. I did everything I intended on doing, and put everything back exactly like it was before. But now I am not getting the heat I used to out of the heater core.

A little background first off: On my road trip home from the mountains, my water pump went out, and then my thermostat. By the time the thermostat went out however, I was in the middle of nowhere, and out of cash. So I just pulled the old thermostat out to make it home without losing all my fluid.

After breaking my transmission, I figured I'd use the down time to repair the little stuff. I originally intended on just repairing the defroster duct, but then I got carried away and pulled the entire thing out, figuring if I have the antifreeze out for the thermostat, now would be a good time to pull the core and ventilation system as well.

So I did just that. I flushed the heater core and cleaned everything up, lubricating moving parts and such. I put everything back together again, and the system works better than before with a few exceptions. The main one is that the heater puts out cool air instead of hot.

I have read more than a dozen threads about this same subject so far today, and from what I can gather, everything is hooked up correctly. Here is a picture of how it sits right now:



According to much of what I have read here, this is the correct way to connect the hoses, and it is the exact same way they came off. After I got everything back together, I left the cap off the radiator and burped the system, though I must admit I didn't actually lift the front end up or anything like that. My tranny is pulled out right now, and I have a jack under the engine so as not to cause undue stress on the motor mounts. And I do not have a temp gauge in the Jeep yet either, though I bought one this afternoon.

After I burped the engine and got the proper amount of fluid in it, I turned on the heater to test the temperature. It was cool air, cooler than the air outside actually. I grabbed the hoses under the hood to find out if they were hot, and all but the top line to the core were hot. Even that one was hot on both sides, but cool in the middle. I lifted it thinking there was an air bubble trapped somewhere, but it remained cool to the touch.

I have double checked the heater box, and everything works just fine except for the vents that open from the outside. All I have right now is recirculated air, but the rest of the system works great. Problem is, there's just no heat.

So where did I go wrong here? I sealed everything up real good so there are no leaks, I hooked everything up properly, and I flushed the core before installing it, making sure it wasn't plugged.

[frank c]

Not trying to be funny but ...did you remember to put a new thermostat back in ????You didnt specifically say so in the post so it leaves one to wonder ??

[Daladim]

I was looking through the pictures I took of the work I did, and I saw this one:



I just went outside and played with it, because it isn't working properly. That's actually the reason I took the picture. But I noticed that it seems to be closing off the duct for the heater core, and opening the system to air from the vent on the cowl. But it only works if I move the mechanism by hand. The pull lever on the dash won't budge it that far. The pull lever only moves the flapper on the right side of the cowl vent. If I want the driver side vent and the one near the floor on the passenger side to open, I have to reach under the dash and move it by hand.

So the way I understand it, I should be getting air through to the core. But I'm not getting heat for some reason.

[Daladim]

Originally Posted by frank c

Not trying to be funny but ...did you remember to put a new thermostat back in ????You didnt specifically say so in the post so it leaves one to wonder ??

Haha! yeah, I put it in. At first I thought I put it in backward because of this problem, so I pulled it apart again and checked. I even asked a mechanic to be sure. And then I burped the engine all over again, and got everything back to where it belonged.

Everything is installed properly as far as I can tell, it's just that I have no hot air anymore.

[bruteboy]

is it possible something is blocking the port for the upper heater hose on the t-stat housing(ie wrong gasket etc)
also it may take some rpm to flush any air out of the heater core and hoses.
lastly,are you sure the blend door(the one that controls temp) is working properly?

[Daladim]

Originally Posted by bruteboy

is it possible something is blocking the port for the upper heater hose on the t-stat housing(ie wrong gasket etc)
also it may take some rpm to flush any air out of the heater core and hoses.
lastly,are you sure the blend door(the one that controls temp) is working properly?

I suppose it IS possible that there is blockage in the port for the heater core. But, I did check that as well. I had the proper gasket with the hole for the port, and everything went together nicely. If there is blockage, it would have to be in the heater core hoses. The RPM idea might do the trick. I was only dealing with idle because the tranny is out and I didn't want to cause problems with the clutch. And yes, the blend door works properly. It went together with a little difficulty on the blend door, but I got it lined up properly by putting my hand inside and carefully aligning the axle for the door. The temp control even moves in and out more smoothly than before, and I can hear the door moving inside the duct as well.