heater core valve or vacuum switch?

[mudbuggy]

I have had an issue with the suitcase under the dash for a while. I have finally gotten the ac back together again, but its not cooling off how it should be. So I was wondering about installing a vacuum controlled water switch on the heater hose inlet. Then I started to remember about some of the trucks that we have around the shop have a summer winter valve on the heater core to stop the hot water from going into the heater core while the ac is attempting to cool the truck off.
So I figured I'd see what everybody does when they have less then a factory suitcase under their dash. It does great heat, and allows a lot of heat out even when the ac is on. Mine is an 89 V1500 with the 350. Thanks for the input guys.

 

[Jessie James]

Have you checked the cable that goes from the dash temp to the top of the box? Mine was broken, so heat all the time. Two minutes and two zip ties later and it's fixed. Just remove your glove box door and you can see it in the back.

 

[mudbuggy]

Yea it works, But a po cut the front off of the box, so I made a cover out of aluminum and some sealant to 'seal' up the front of the box. The cable operates just like it should. Thanks for the idea

 

[4xcrazy]

Mine has a vacuum operated switch closing off the water to the heater core unless on heat setting, been told several times it's not a factory thing, I am the second owner of the truck and it was in there when I got it. Looks factory, I dunno.

Works good unless I'm on the throttle real hard for real long, but that may be because the vacuum canisters were removed by me earlier due to bad hoses.

I was also going to replace it with a manual valve anyways, since we really don't use much heat here in Arizona.

 

[Jessie James]

Have you thought about replacing the heater box entirely? You know, replacing what is cut up with the OEM setup?

I would be curious to see a photograph of your setup. Depending on what is cut off and removed the fix may be a simple trip to the junk yard or classifieds section and $20 and a few screws.

Or maybe not ...

 

[mudbuggy]

With my luck, lol. I'll dig up some pics or take more for ya if I remember when I get home tonight.

 

[Jessie James]

I don't mean to put you out or anything, I am just wondering if it's some simple fix that would make life easy for you.

 

[mudbuggy]

Ha thought that I forgot didn't ya. I actually did, honestly. I wanted to get a picture of the suitcase on my pda anyways. It's not the best, but you can get an idea of what I had to start with and what I attempted to do with the finished product. Neat thing is that it doesn't leak from the perimeter of the suitcase, just through the vent system.

 

[Jessie James]

Wow, what a creation. I'll crawl under my dash once it's light tomorrow and maybe see what's up.

My first thought it that the box you have does not allow the blend door inside to properly close off the heater core. While it's a bit of work, if you replaced the cover under the dash with the factory unit I bet your problem would be solved. The question is (1) can you get one (2) is it easy and cheap to get it and (3) which takes more time to complete and works best...

 

[mudbuggy]

Well that's why I was going with this line of questions, since I'm not really sure what happens if too much water builds up on a vacuum switch then just closes it to relieve the pressure. Or if I should just install a ball valve and bypass the heater core all together during the warmer months. I now am thinking of installing the ball valve just since I know that it won't over pressure or anything, I am worried about the heater core. What happens when the water doesn't move through it, does it begin to eat away the inside of the heater core?


Thanks for your time Jesse, I am looking forward to seeing a factory setup and what difference there is to what I put together.