Cockpit heat

[WAM174]

I've got a some unwanted heat leaking into the footwell areas. Probably some doors not closing or sealing properly or something. I was all set to simply put a shutoff valve in one of the heater hoses (4.0) when I read something about Jeep using the heater core flow to even out hotspots or something. I guess there is no separate bypass route. This is on my TJ, but I doubt it's much different than the XJ.

Anybody know anything about this? Obviously I could just connect the two hoses together bypassing the heater core, but that's too much work for when I do need the heater.

 

[CaliXJ]

Yeah it would be a lot of work when you actually need the heat. I'm guessing a TJ doesn't have a heater control valve? Maybe you could add one the you would just need to connect a vac line to open it when you wanted the heat to work. Or figure out if the heater control is vacuum actuated and tie the HCV into that. The HCV will bypass all that hot coolant till you actually need it.

 

[WAM174]

If there's such a thing as a bypassing heat control valve, I wouldn't care if I had to work it manually under the hood. But I don't think my XJ has one of those either. Are you thinking of anything specific? Like from a certain model & year? It would have to splice into both heater hoses and divert the coolant from the heater core straight back to the engine.

I'm sure I could build one from two ball valves and a tee, but something made for the purpose would be nice.

I guess the other possibility would be to dive under the dash and see if I can seal off the hot air better. But I hate working in areas I can hardly reach trying to do something when I haven't a clue. I don't pretzel up like I used to.

 

[CaliXJ]

Google or search here for "heater control valve" tons of info. Most going away from them like post 96 IIRC. Or just getting a replacement. For the cost in parts to make something, you could get the right part. Or just fix the climent contrl door under the dash.

 

[hubs97xj]

This is on my TJ

XJ OEM tech is probably not the right place to ask TJ OEM tech questions.

 

[CaliXJ]

:dunno: Pretty sure the TJ and XJ motor and heater set up is the same. Thats a huge guess though.

 

[WAM174]

No it's not XJ OEM tech. But I'm looking for a creative solution and both rigs use the same engine. Just looking for people who have messed with this already, and the sheet metal isn't going to matter. I have both an XJ and TJ and am not seeing any obvious heater design differences.

I found some of the threads CaliXJ referred to, but they kinda convinced me that if I want a redirection system, I should build it myself out of brass valves. That plastic HVC isn't very popular.

It would be real easy to do a simple shut-off but do you guys generally agree the 4.0 needs flow thru the heater hoses to deal with engine hot spots?

 

[CaliXJ]

You are correct about it not being popular thats for sure. LOL One more thing to fail in the cooling system. You def need flow from the t stat back to water pump. Either a few t's and valves to block off heater, or making a U shaped connector and eleminating the heater all together. There has to be some sort of flow between T stat and pump though so the coolant can go somewhere before t stat opens.

 

[WAM174]

You are correct about it not being popular thats for sure. LOL One more thing to fail in the cooling system. You def need flow from the t stat back to water pump. Either a few t's and valves to block off heater, or making a U shaped connector and eleminating the heater all together. There has to be some sort of flow between T stat and pump though so the coolant can go somewhere before t stat opens.

Perfect. Exactly what I needed to know. Thanx.

 

[kastein]

Huh, I'm running fine (even a bit cooler than usual) on my 98 with both heater core lines blocked off due to my heater core exploding a while ago. I wonder how big a deal it is - I was on the road when it blew, and basically had 15 minutes in the home depot plumbing aisle to find materials and tools, fix it, and continue driving, so I didn't really put much thought into it at the time.

You could build a bypass setup pretty easily with a pair of ball valves. One to connect the heater core, the other to shunt by it. All you would need to do is make sure you never turn both valves off I guess.

 

[Ecomike]

The valve is a pipe T and valve all in one, called a three way valve, vacuum operated. A simple pipe T and two ball valves or gate valves will make a manual version.

You leaky air problem is likely an inside/outside air control damper that is vacuum operated that is not getting vacuum due to a hose or tube or diaphragm leak.

 

[WAM174]

You leaky air problem is likely an inside/outside air control damper that is vacuum operated that is not getting vacuum due to a hose or tube or diaphragm leak.

Maybe that was just on earlier models. It seems late model Wranglers and Cherokees used a computer controlled electric motor actuator.

This video is trying to sell replacement blend doors but it has good info on the actuators and blend doors for Cherokee & Wrangler 97 to 06.

http://www.youtube.com/watch?feature=player_embedded&v=LKTMnL_5pHw#!

 

[old_man]

You can get the valve for an 85 2.5L w/AC IIRC. It is vacuum actuated and does the bypass automatically.