Need some ac/heater help

[hdff]

I just finished going thru my ac and heater. When I bought the ac cab truck the ac wasn't working and the heater core leaked. I refurbished the heater box and core and evaporator. I also put everything back under the hood, compressor,condenser, all of the hoses and hot water valve. Everything is back together except I have NOT filled it with R12 yet.. While driving with the vent on and outside air selected the air comes thru a little warmer than the outside air as to be expected. When I slide the selector to inside air the air gets hot like the heater it on. Does this sound right? When I slide the selector knob the vacuum opens the vent on the kick panel and closes the one under the cowl, and I assume makes the hot water valve move, but why would it open the hot water valve at this point? If I left the top lever on inside and slid the second lever more to the left to ac I would not think I would want the hot water circulating while the compressors is on trying to cool. Do I have something wrong? Am I thinking right? If not that compressor is going to work really hard to cool that hot air.. Any help will be greatly appreciated.. It looks to good not to work right...

[snipescastle2]

I believe the vacuum is applied to the valve normally when the a/c position is off, so that said, when you select a/c, the vacuum is shut off to the water valve. I'm sure someone will chime in with a schematic ( I'm out of town currently, and don't have my computer in front of me) i'll see if I can find one for you online..
Ben

[snipescastle2]

Picture

[Andy4639]

Make sure the hot water valve is operating correctly. I have always installed a manual valve in line to make sure the flow is shut off. Just a little water flow will cause heat in the truck when the AC is on. Mine cut a good 5* off the temperature inside the cab.

[hdff]

Originally Posted by Andy4639

Make sure the hot water valve is operating correctly. I have always installed a manual valve in line to make sure the flow is shut off. Just a little water flow will cause heat in the truck when the AC is on. Mine cut a good 5* off the temperature inside the cab.

The hot water valve is new, but these days that means nothing...... Where did you get your manual valve, does someone make one specifically for that purpose? I'll do some more checking when I get a chance. As I recall both sides of the valve are warm/hot all of the time

[Andy4639]

This is the one I use. I got it at Ace hardware locally several years ago. I have it mounted up close to the fire wall.





http://www.autozone.com/fuel-systems/shut-off-valve

[snipescastle2]

Good info for sure! I know there are two versions of the vacuum control switch (A/C control panel) three ports -vs. two ports,I believe the three port version eliminates the need for a "tee" hope this helps.....
Ben

[Andy4639]

Crank the truck up and put the AC lever in the positions you mention and go around to the valve and see if it's operating by taking the vacuum line loose at each setting. This will tell you what is going on. It could be the valve itself isn't fully shutting off also which is why I install the manual valves.
If your truck has a big cam are very little vacuum it want close all the way.Per drawing vacuum applied closes the water valve so you have to make sure your hooked up correctly to the valve port on the dash assembly also.





Here is the 3 port connections.

[hdff]

Originally Posted by snipescastle2

Good info for sure! I know there are two versions of the vacuum control switch (A/C control panel) three ports -vs. two ports,I believe the three port version eliminates the need for a "tee" hope this helps.....
Ben

could you explain a little more on the 3 port. I had read that I needed to plug off the 3rdport and tee the second port twice, once to go to the kick panel vent and once to go to the hot water valve before going to the cowl vent. so if I read this right the 3rd port should go directly to the hot water valve eliminating the T in the engine compartment. I have mine hosed like the illustration for the 2 port

Originally Posted by Andy4639

Crank the truck up and put the AC lever in the positions you mention and go around to the valve and see if it's operating by taking the vacuum line loose at each setting. This will tell you what is going on. It could be the valve itself isn't fully shutting off also which is why I install the manual valves.
If your truck has a big cam are very little vacuum it want close all the way.Per drawing vacuum applied closes the water valve so you have to make sure your hooked up correctly to the valve port on the dash assembly also.





Here is the 3 port connections.

the hot water valve is all enclosed so there is nothing really to see other than feel the hoses which they get hot the experiment is over. in this 2nd pic it looks like a 2 port head and is hard to see exactly what is hooked to where. the 2nd port looks like it does directly to the hot water valve and the cowl and kick panel tee into the main vac line from the carb.......
what service manual did you get this 3 port from. I just looked again at my 71 manual and it doesn't show that pic, it shows the top pic

[Andy4639]

Taking the hose off the water valve and put your finger over it to see if it pulls on it are not. The 3 port was for 71 model trucks and up. The port on the bottom of the picture is the water valve. The center one from motor vacuum and top goes to each of the flappers outside closes with vacuum inside opens with vacuum.
Checkout the new picture it's highlited!

[hdff]

Originally Posted by Andy4639

Taking the hose off the water valve and put your finger over it to see if it pulls on it are not. The 3 port was for 71 model trucks and up. The port on the bottom of the picture is the water valve. The center one from motor vacuum and top goes to each of the flappers outside closes with vacuum inside opens with vacuum.
Checkout the new picture it's highlited!

thanks andy, pics and illustrations help me out a lot. I will go get some more tubing and re pipe it . you said the motor vac goes to the middle port but your illustration shows it going to the top and the middle going to the vac doors.. may be a couple of days before I get a chance to redo it but I will report results.
what book is your diagram from?

also no cam stock motor

[Aus69c20]

Very helpful thread. I'm about to tackle my a/c and my vacuum side of things is a mess. Thanks guys

[Andy4639]

Originally Posted by hdff

thanks andy, pics and illustrations help me out a lot. I will go get some more tubing and re pipe it . you said the motor vac goes to the middle port but your illustration shows it going to the top and the middle going to the vac doors.. may be a couple of days before I get a chance to redo it but I will report results.
what book is your diagram from?

also no cam stock motor

Yea after blowing it up to paint the hoses the picture is correct for the routing!
71 shop manual. The 2 prong was out of a 69 manual.

[hdff]

Originally Posted by Andy4639

Yea after blowing it up to paint the hoses the picture is correct for the routing!
71 shop manual. The 2 prong was out of a 69 manual.

I wonder if there are different versions of the 71 shop manual? Mine shows the 2 prong which was confusing yo me

[hdff]

Here's the book didn't upload on the previous post

[Andy4639]

I have both manuals so I may have told you back wards then. The three prong maybe is the 69. I'll have to look when I get home this afternoon.

[cdowns]

me i'd get rid of that rubber fuel line b4 the fire burns your truck to the ground

[hdff]

Originally Posted by cdowns

me i'd get rid of that rubber fuel line b4 the fire burns your truck to the ground

Can you point me in the direction of a metal one for an edilbrock carb with a filter?