While I'm messing with this heating cooling stuff another question. My manuals do not show any hose routing information or coolant diagram for my Cleveland. Which outlet by the water pump would be the feed for the heater? I want to make sure the vacuum flow valve is in the correct one and facing the right direction. My A/C is getting really cold at all exposed areas in the engine compartment but the air at the vents doesn't seem as cool as it should be.
From the centerline of the engine, the inboard hose goes to the core and has the control valve in it. I suspect you have a control door issue... do you have the shop manuals or are you using something else?
I do have all of the blue shop manuals and to my dismay they dont have any diagrams in any except a redundant lot covering the vacuum system for the A/C heater. Looking at your diagram my engine isnt configured the way it is. The control valve is in the inboard hose but the inboard hose is connected to the fitting your outboard hose is attached to in the diagram. My intake manifold has no water port in it. My outboard hose is attached to a nipple that sticks straight out of the timing case cover below the angled one in your diagram and almost behind the alternator. I hope that description makes sense. I could take a picture and send it to you. I kind of glanced at the control door info inthe manuals and wonder how many years it would take me to figure it all out? I know I might have to go there next.
I'll take a picture of a Cleveland with the correct arrangement this evening and post it for you, but the water nipple at the front of the block just in front and below the radiator hose is the "outboard" line that runs to the outboard heater core nipple. The line from the water pump casting is the inboard line and runs to the inboard nipple on the heater core, and that line contains the control valve. That is really just a loop, reversed wouldn't truly have much of an impact, especially since a plenum control door directs the air either through the evaporator flow path or heater control path or both, depending on control settings. My A/C Plenums are in the process of being overhauled now, I have them apart so if you think a picture or two of them disassembled would help let me know. Volume 3, Page 36-35-07 has a pretty good diagram of the control vacuum hose routing. I would test each of your vacuum motors in the A/C Plenum to make sure that they hold vacuum, but the temperature control door is cable operated and the first check I would do is to make sure that you get full closure of that door when the cable lever is full left (cold) on your control panel. I noted with mine that they can be a little stiff and you may not be getting it closed off completely.
My heater hoses are configured ok and water valve is in the proper place. That plenum control door is the next check. I've studied the manual and it mentions a turn buckle adjustment for the plenum control door. Where is it located and what do I have to remove to get to the door to see if it's fully opening and closing? I just ran a temp test and I have 69 degree air coming out of the vents in the dash w/fan on high and in recirculate position. If I put the thermometer on the stc valve or the muffler it is 50 degrees. I also played with the temperature lever. I had thought when it reached the approximate #3 position in figure 4, page 36-35-06 (where I feel a change in the resistance of the cable) the water valve was shutting off but that isn't true. The water valve doesnt go off until about the last 1/4" of movement of the lever to the left, by that time the recirculate vacuum motor activates. So there doesn't seem to be a fresh air cool position with the water valve off. Even when in the vent position the water valve is open to the heater core if I have fresh air coming in.
Let me get some pictures of things and we'll work from there... the turnbuckle is where we need to be adjusting next. Your STV temp is pretty high... do you have a sight glass on the driver side front A/C line running into your condenser? If so, can you clean it and then run the car with A/C on and see if you have bubbles in the glass?
Here is an open heater plenum... the heater core rests in the rectangular cavity behind the Heater Control Door. If that door is fully closed, the heater is completely isolated from the air flow inside the car. The lever at top the arrow is pointing to is the control lever for that door - if that lever is pushed full travel to the firewall that door is closed as shown in the picture. This is the control cable with turnbuckle, you will locate the turnbuckle under the driver side dash at approximately the same position as the wiper switch. Set the heater control to cold (full left) and adjust the cable length via the turnbuckle to ensure that door closes fully. The only real easy way to see if you are getting that door closed without taking it apart and removing the heater core is to remove the glove box and visually check to see if that lever is moving forward to about the end of the metal cover over the cable attachment point.
I spent some time in the manual today and then took out the glove box. After some hunting I found the adjuster and adjusted it according to instructions. It was off a very small amount but now when I move the cable quickly left I hear a clunk at about the three position in figure 4. So I'm pretty sure the door is closing completely. The site glass is clean and there are definitely bubbles in the site glass. It was originally chrged with the amountof freon the book said to use. There have always been bubbles but another friend said some bubbles are ok. Even after I adjusted the cable the water valve doesn't go off until I move the lever far enough left that the recirculation door closes off the outside air. I can now sort of feel three positions at the left end of the travel but don't understand the point for the 2 position.
Okay, yes some bubbles are okay... but what are the pressures? You should be seeing around 28 to 30 pounds on the suction side IIRC. At this point I would verify that all air plenum motors will hold vacuum and that with each setting on the panel function control you have air flowing where it should and not where it shouldn't. A failure mode is supposed to result in defrost so if you have air flowing out the panel registers and defrost you have have a motor failure or a control unit failure. Once you have verified the air plenum is working correctly the final test is temperature output. Basically, when you are at setting one, and the car has had a chance to run the A/C for a while, the temperature at the center registers should be 38 to 42 degrees. If is above that and there are no air handler issues it is time to put the gauges on the system and validate the correct charge. For what it is worth, when my system is up and fully charged I don't see any bubbles unless I cycle the compressor.
Tomorrow I will check each vacuum motor. The system distributes air everywhere it should for a given setting. Even several minutes after shutting off the motor if I change a vent setting I hear the motors go into motion until the vacuum is gone so the system is pretty tight overall. I guess I'm used to GM systems. When you put earlier GM AC controls from A/C to heat the compressor shuts down and re activates when Defrost mode is entered. Also I just don't see the point in the water valve staying open to the heater unless you enter Max A/C mode. I know you said the core is isolated when the door is closed but it still puts a lot of constant heat in that portion of the plenum and inside the cabin where there has to be some reflected heat affect. I know, now I'm just B'in but working on this kind of stuff when you've never had any of it apart is frustrating so don't pay any attention to me. Just know I'm grateful for the help!
Since your system is holding the pressure (or lack of it) then I wouldn't worry about chasing each motor at this point. A leak would deplete the reserve in the tank in short order. Test them if you want peace of mind but they are probably all okay. One of mine has a bad one and you can hear the pressure bleed off when you turn off the car. The heater valve disturbs me a little, I don't seem to have any flow through mine until I am at position 3. At this point, with all the doors appearing to function correctly, I would look at the outlet temperature at the register. I use the standard A/C tech thermometer that has a little dial face and a 4 or 5 inch "stem" placed in one of the two central registers (I just leave one in there all the time clipped to one of the deflectors) and see what the output temperature is on a 30 minute or so drive. I let the car get cool and then use full cold setting and fan on low. It should get to the range of 38 to 42 degrees and stay there. If it doesn't then you probably have a low refrigerant charge.
Hey 72GTVA I finally have ice cold air in the GT. After all our discussion went back to the basics, went through everything from the beginning and found the new STV valve I installed with the reassembly was defective. Also found a tiny leak in the hose across the engine (I left it on the vacuum pump for twenty four hours originally and it held perfectly). At any rate I'm good to go and I learned a lot about my truck with our discussions. I guess I'm still a little frustrated with the late shutoff of the water valve but I drove it yesterday out of max cool and even with the valve still open it doesn't seem to have much if any effect on my cooling with that door completely shut. Thanks again, have a great day!
