Cruiser54 quote: "I actually rarely use AC."

You would if you lived where I do. The hot and humid Southern US. Where the actual temperature can be 114 degrees with a heat index of 129.

For weeks on end.

You lucky people in AZ and WV just don't know.

You'd be looking for a way to put three heater control valves on your Jeep.

 

Cherokee Chick, Does your Idle fluctuate every 20 seconds or so? Sort of slow down, nearly die, then surge up a sec, then repeat?

 

For those who want to run an HCV I had thought about trying this metal one available at Rockauto among other places. Part #74800




We get those kind of temps and humidity here to,firestorm500. "Almost" looking forward to them considering what this winter's been.

 

Yeah this has been an unusually cold winter for us with several ice and/or snowstorms. Temps way below average for a long time.

O'Reilly's sells a Murray part that is all metal too. Part number is is 74774. List is $66.08.

 

Waste of money.

Seriously, why are you guys so bent on the HCV? Tons of vehicles don't have this sort of mechanism and do just fine. If I owned an XJ of the era that had them, it'd probably be the first mod I'd do.

 

You might have a point. Daughter's (former) boyfriend is buying my '87 Pioneer. He burst a hose and valve about 1 1/2 weeks ago. He knows nothing about mechanical things. He only saw white smoke coming out from under the hood early one morning while running his rural paper route.

When Jeep dealer looked at it, they found the burst hose and valve. They said it would take them a week to get one in and that it would be $275 parts and labor.

The Jeep is 250 miles away from me one way. This kid doesn't have that kind of money right now. I told them to just leave the valve off and plumb the heater straight from the engine.

The (former) boyfriend reports he has MUCH MUCH better heat now, he was about to freeze at 0-5 degree temps and just idling around, opening the door or window frequently to throw the papers. 40 mile route.

 

I've got no problem with canning that POS Jeep valve. Both my 84 and my 90 have gone bad at least once.

On my trip home today I left the heat on full, and the vent set on off. It's 48* out, and I could not only feel a little heat, but got a reading of nearly 80 from the heat gun. (see photo). On a hot day that is not more than what would be coming in the window! I suppose being stubborn I'd still install a shutoff under the hood, but it looks as I may not ever opt to use it!

 

Then your blend door is out of adjustment....

My vents blow outside air temp.

 

I did check it last year. Or the seals are 24 years old. Mouse chow! In any case as you read, I'm agreeing.

 

My seals are just as old...

 

Soooooooooo...

According to DFlintstone's test, heat does come into the box at all times without a HCV. So it has a purpose after all, as I suspected.

All the justification of blend door adjustments and old seals don't change that fact.

Especially when you use a plastic tie on the lever.

Now when you are using the A/C, it has to fight that constant heat source before you ever see a breath of cool air coming out of the vents. In some climates, and with some people, it wouldn't matter all that much. Maybe.

But maybe they don't remember or realize how much better their A/C could be if they had the valve. We'll soon be going from posts about poor heat to posts about "my A/C is not blowing as cold as it should."

I fully support Cruiser54 and others doing what they want to, to their Jeep.

But I think I am going to stick with the factory arrangement for now. I really like cold-as-possible A/C in my region.

Land of the free and home of the brave, folks.

 

But, we don't know if Flintstone's blend door is adjusted properly....

I get outside temp air from my vents without the AC on, and with AC on the vent temp is 44* on a 90* day.

Besides he's using an IR gauge, not a vent thermometer. He could be picking up the dash temp as it's heated by the sun........

 

I may be all wet but it just seems to me that when coolant is stagnant/not circulating thru the heater core, the chance for corrosion to form inside the heater core increases.

 

You're not all wet. That's another added benefit of eliminating the HCV.

 

My conclusion is that if it's letting 80* air in, fine. I likely would not want the AC at 80 anyway. (close call there). It was not sunny, raining mostly. I intentionally measured the plastic of those glasses there in the rising warm air. As far as the core, I'm not seeing nothing coming in, causing something to be there. Seems more likely flow could bring stuff in. It's usually sitting still anyway. If something is going to react/corrode, it's going to do that regardless.

I can put a different thermometer in there tomorrow. I'd like to double check that IR deal anyway. Likewise I can stick a hydraulic jack in there to make sure the door lever is over.

I found this in my barn, from the 84 I think. Metal, but I needed to get creative over some leak until I found a replacement. IIRC.