Topic: hot in the cab

[damon54]

It has always been hot in the cab of the Wrangler and it just occured to me that whenever the thermostat is open hot coolant is flowing through the heater core.  On my Cherokee with the 4.0 there is a bypass valve for this which opens and closes from the controls on the dash ac/heater unit (I know cause I broke it when I disconnected the heater hose).  It all looks stock but I just wanted to check and make sure that I was not the victim of Southern Engineering.  If that is the way its set up I wonder if the by pass valve from the 4.0 can be modded to fit the 2.5.

[Jeffy]

What year Jeep is this?  I know on my YJ, the heater core does not flow when it's off unless I switch around the vacuum lines.  I can set it up so the core will flow even when it's not turned on.

[damon54]

It is a '92.  The two heater hoses connect directly to the core with no valve or anything in between.  The valve on my Cherokee is vacuum activated.  On the Wrangler Don't see any way that the water flow could be shut off.  Do you have any pictures of your setup?

[Jeffy]

It is a '92.  The two heater hoses connect directly to the core with no valve or anything in between.  The valve on my Cherokee is vacuum activated.  On the Wrangler Don't see any way that the water flow could be shut off.  Do you have any pictures of your setup?

The vacuum lines for the heater are above the ash tray on the driver side.  You should see a green vacuum line as well as one other.  I think it's white.  They will plug into a manifold.  I think there are 3 ports on the manifold.  The white line stays put in the middle.  The green one can be moved.  I'd have to look up which port the line is supposed to go into though.

[damon54]

No manifold or lines above the ashtray then again I don't have an ashtray either.  There is a vacuum manifold on the back of the dash unit and it had one green line in the middle but no other lines attached to it.

[Jeffy]

No manifold or lines above the ashtray then again I don't have an ashtray either.  There is a vacuum manifold on the back of the dash unit and it had one green line in the middle but no other lines attached to it.

Well, above the ash tray is the HVAC controls.  There should be a second vacuum line someplace.  I forget where it comes from though.  It should be black.  The green line plugs into the center port on the manifold with the black on the outer port.

This is most likely the reason why your heater core is always open.

[damon54]

I have completely dismantled the dash and heater unit because it was so screwed up in the first place.  I have everything seperated and no black or white vacuum lines just the green one.  It doesn't suprise me though.  The previous owner had a rats nest of wires from where they "rednecked" an air conditioner in there, duct tape and all.  I had to gut the whole thing.  The dash metal was rusted through so I replaced that.  I have a 94 wiring harness to go in there.  The heater unit is just another thing on the list.

Thanks for the info.