Looking for ideas for upgrading my A/C...

[red71cheyenne]

I want mine to work better. Part of the problem is the diverter box is worn out, but wondered if anyone had come up with a better way to do it. I was thinking about making the a/c switch a stand alone affair so I could have it on with the defroster to help that out. I'll post pics as I go along and hope if you have a suggestion you will too. Thanks, Jeff.

[Project1970]

The most upgrading my A/C has seen:

*Disconnected stock fan-speed switch after melting down the third or fourth one in as many years, and added a DPDT switch and two relays to control the fan and A/C clutch.
*Ghetto heater control valve: vacuum-control valve is long dead, so replaced with a hose valve.
*Ghetto conversion to R134: POA adjustment, can of stop leak, a few cans of R134a. When the truck last ran, it worked pretty good for such a small investment.

With the LS1 swap coming, I'll be adapting its compressor into the system. I'll probably see if I can find something to flush the system with before I hook it all up.

[chickenwing]

I've been thinking about using an evaporator from a later model truck. Could then upgrade to a new new style of variable expansion valve. Sure there is more to it than that... Still lookin/tinkerin/thinkin. Here's a link for the variable orifice. http://www.acsource.com/index.asp?Pa...S&Category=273
Check em out. They have plenty of a/c tools on the kinda cheap.

[red71cheyenne]

Project: Mine melts down too. Have you had any trouble since going to the DPDT switch?

Chicken: I intended to just leave mine R12 and try to sort out the whole air routing thing. Last time I had mine serviced they said it cooled fine, just couldn't shut off the hot air well enough to stop it. Think my heater valve is shot too though. Where did you get your newer one?

Thanks and keep those ideas coming! Jeff.

[chickenwing]

You must have seen 1 of my few pic posts? Otherwise ur physic! Got it at Autozone if I remember right. I like the color of it. I really think the blower switch tends to burn up because of the rotten ground design on the a/c relay. The relay has a bonding strap that uses the relay mounting screw to keep contact. Since the case is plastic? the screw tends to back out causing the relay to have an intermittant ground. I've posted on that subject a couple of times.... No one has told me I'm full of crap yet, so it might be an accurate guesstimation.
If you figure out how to fix that diverter door without welding I sure would enjoy the write-up on it. I've managed to totally destroy 1 so far.
Oh, I like the idea of having a stand alone ac switch. I've been snooping around looking at various oem button switches. If you have an idea on it, post it?

[barn9]

I went the same route as Project1970, other than as to the switch, a wiring upgrade solved it for me. Had an old GM mechanic tell me the original wire wasn't big enough, and after upgrading it, no more problems (so far).

[neonlarry]

I am going to use a newer compressor mounted on a serpentine bracket(still R-12).
To solve the switch melting I am going to use it to control relays to switch the main power supply.
Getting the diverter box working properly will help. They can be repaired with fiberglass or metal straps. Its almost always the plastic flapper valve that breaks off of the metal rod that moves it. Also its a must to get the hot water shut off valve working otherwise you have all that hot water running through your heater core heating up your A/C's cool air.

[chickenwing]

Neon Larry, any tips on that diverter box repair? Do ya got to cut the box in half to fix it? Also would you like to motor over to Sacramento Saturday for my mini car show? Would like to meet another board member.

[neonlarry]

I haven't repaired one just know it can be done several ways. Like in that last post welding onto that metal rod or using fiberglass. I don't think it needs to come apart just some careful work in a tight space.
If the stars line up right I might be able to make it Sat sans either the truck or burb both are apart right now.

[Project1970]

Originally Posted by red71cheyenne

Project: Mine melts down too. Have you had any trouble since going to the DPDT switch?

Aside from my waterpump cracking in half and transmission blowing up?

Seriously, though, the switch is a roaring success. The fan moves faster than it ever has (side note: I actually had to use screws to attach the fan back to its hub because it kept coming loose from that pot-metal hub) and the A/C clutch works no problem. It's really pretty simple, too; I use the passenger-fender lug to feed both relays on the high-current side, and spliced the old wires for the control.

[red71cheyenne]

Project: How about some pics and maybe a diagram of how you wired?

I forgot to take pics yesterday, but the evaporator came out pretty easy. If you take the bolts out of the housing under the hood, next to the engine, that piece just lifts off. Then take the evaporator out of the case and lay it on top of the compressor. Have to do a little line bending(real easy like) to get it out of the housing. Also helps to take all the mounting brackets off the lines too. Once the evap is out, the housing just bolts to the firewall. Pulled it off and of course it was full of crap. Cleaned it out and now the flapper door works fine. Put all that back in last night and today I'm going to reinstall the inner box in the cab.

Still haven't figured out how to run the a/c stand alone, but was thinking about looking at Radio shack for a voltage divider, or switching device that can handle the load of the motor. I ran it straight from the battery last night and it worked fine, no heat in the wires. I personally think the heat that is frying the switch is due to the blower resistor. Its just coiled wire that is serving as a voltage divider to give you different speeds. Run voltage thru wires and it creates some heat. Run more voltage thru, and more heat. Hence the reason for looking for something solid state to divide the fan speeds.

I'd also like to get away from the old hose system of delivering the air. They are hard to get on and off and take up a lot of space. After all my upgrades, I have lots of stuff behind the dash and there is only so much room. Anyone thought of using collapsible tubing? I was thinking about the kind you use for moving air while painting spaces. Something like that. I'll get some pics today and post them tonight of my progress. Later, Jeff.

[red71cheyenne]

The screws are marked in the circles. Just remove the two on top, two on the sides and there are two on the bottom. They are 3/8 head, self-threading. At the top of the box there are also two 1/4 head sheet metal screws that have to come out and then the whole thing will lift off to the engine side. Jeff.

[red71cheyenne]

Oh, it will also help to remove the fenderwell as you can see in my photo. Makes it easier to get to the bottom screws and helps removal of the whole thing. Will also aid me in replacing the passenger header which will happen tomorrow! :p Jeff.

[Project1970]

I absolutely suck at diagrams, so an explanation will have to do for now:

Parts list:

• 2 Bosch-style 30A relays
• 3 inline fuse holders - get the sealed mini-blade type
• Some lengths of 12ga wire and proper connectors
• A DPDT switch of desired size / appearance from Radio Shack

0. UNPLUG THE BATTERY!
1. Decide where to mount the relays. I put mine on the inside of the passenger fender, near my Ford-style starter solenoid and just above the wheelwell.
2. Run two fused wires from the +12V lug on the passenger fender - these are your high-current feeds.
3. Find a good ground for the coils and run a wire from '85' on each relay to ground.
4. Pick one relay to be the blower-motor relay. Connect a high-current feed to terminal '30', then run a length of wire from terminal '87' (these two should NOT be connected when the relay is not engaged) to the lug on the blower motor.
5. Look at your switch - it should have terminals in a 'six-pack' arrangement, 3x2. Hold it so it's three terminals wide, and two high; the center of each row is the power-in, and the ends correspond to the two 'on' positions. Mount the switch in the cab and run a fused wire from your favorite +12V feed to both of the terminals in the middle.
6. Run a wire from the '86' terminal of the fan relay to inside of the cab, and connect it to both ends of one row - this way the fan will be on in either position. You should have two terminals left open, on opposite ends of the switch. If you like, you should be able to test the blower motor now after plugging the battery back in - you DID unplug it, right? Just flip the switch from the middle to either "on". If it works, unplug the battery and move on.
7. Run the other fused high-current feed to the other relay's '30' terminal, then connect this relay's '87' to the hot wire on the compressor clutch (normally green; the other just goes to ground).
8. Run a wire from '86' on this relay to just ONE of the open terminals on the switch in the cab. Check all connections, plug the battery back in, and test it out - fire up the truck with the switch off. Flip it in one direction, you should have just the blower; flip it the other and you should hear the compressor lug the engine down as the A/C kicks in as well.

You won't have any form of fan control other than off and on, but IMO this works great.

[red71cheyenne]

Thanks for the directions Project. I'm going to look at radio shack like I said for a variable speed controller and see if I can get that done. Reinstalled the air box in the cab today, but didn't go any farther til I get the fan control wiring figured out. Did get the new passenger side header on though, just need to finish up the a/c compressor install tomorrow. Here's a pic of the new header installed.

[chickenwing]

Red71, First off, nice engine!!! After thinkin bout it, it would make since that the resistor might be heating up the switch. The wire that burned on mine was the brown feed wire to the switch so I really don't know wich speed heated it up. Jumped to conclusions when I found the bad ground on the relay. (it does work now though)
To keep the factory switch you could turn the two resistor feed wires (lt blu and yellow I think) into relay control wires. Then use another fused power source controlled by the relays to the resistor. I'd still replace the resistor. This way all that current stays out of the switch altogether.
Never thought about using collapsable tubing for the distribution ducts. Have toyed with the idea of thin wall pvc. Sharp angles with fittings and shollow angles with a heat gun. Then paint it all black with a paint for plastic/vinyl.

[GMC Jim]

In reading the previous posts; regarding the blower switch....I do agree if most, (if not all) problems with switch burnout ; is caused by loose wire connections at the relay. As in many other cases of electrical problems a bad ground is many times the culprit. The blower motor used with the 4 Season air conditioning system has a current draw of 16.5 amps ( max ). The purpose of the relay is to relieve the switch of the higher amperage when the switch is in high blower position and maximum amps are drawn. In the other blower switch positions, resisitors are switched in series with the blower motor. The resistance lowers the blower motor speed and also the exess amperage is disipated in heat at the resistance wire pack. Another condition that would cause excess blower amperage ( in all switch positions ) ; would be a blower motor with bad bearings, commutator or brushes. If the blower motor makes an excessive noise; then the motor is suspect....After all, the age of the blower motor could be in question; hence it's condition!... If the blower and the wiring is in good condtion and of the proper size (s); there should be no problem with switch burnout.

[GMC Jim]

'Diviter' box repairs:--Following 'flappers' or doors are used with the Four Season air conditioning system.
1. Outside air inlet valve
2. Recirculating air inlet valve
The above listed doors are controlled by vacuum operated diaphragms as
dictated by positon of the control head vacuum switch.
3. Temperature door ( controls amount of air thru the heater core or evaporator)
4. Outlets door ( controls amount of air thru the air conditioing outlets or heater
floor outlet.
5. Defroster door ( controls amount of air thru the heater floor outlet or the
dash top defroster outlets.

When I modified ( and/or) repaired the 'flapper' doors when I acquired the truck in 1989, the diverter box was disassembled as far as possible to enable the proper repair. After studying the system controls ( cable and vacuum actuated); I decided I would disconnect and plug the vacuum lines controlling the recirculating and outside air. The outside air valve was fixed to the open position enabling outside air to the system at all times. The recirculating air inlet valve was fixed to the closed position; ensuring that outside air would be used. Reasons for the modification were that myself, wife and friends were all smokers at that time and use of outside air did clear the smoke out of the cab as was desired..,. Also there would be no leaks from the vacumm hoses and diaphragms controlling these outside/recirculating flapper doors.
Inspecting the operation of the temperature door, found that the door was loose on the shaft and the door would not fully seat in either position. As I had been doing some boat repairs at that time; I had expoxy fibreglass resin, hardener and fibreglass cloth on hand. I examined the position of the door in relation to the arc of the control on outside of the box. This is important as the actuating arm as controlled by the cable from the dash control has to be positioned so that control cable travel will be proper to close the temperature door at each end of the doors travel. In other words you will want the door to direct all the air thru the heater core at one end of it's travel and direct all the air thru the evaporator at the other end of travel. I examined the rubber attached to the door edge and replaced for a complete as possible air seal in both postions. As I recall, I used rubber cement for this portion of the repair and used the rubber from an old truck iinner tube. After again checking for proper postion of the door, I cut a piece of fibreglass cloth of proper size to cover both sides of the door and leave about 1/2 inch from the outside for the rubber seals to seat properly. I used a hardener that would set up the expoy mixture in about 15 minutes and coated both sides of the flapper door; moving the door back and forth as the expoxy hardened. This was done to prevent the expoxy from 'glueing' the ends of the shaft which would prevent the flapper from moving ! had some silica filler from my boat repair project and mixed this with the remaining expoxy... Amount of filler used was to bring the expoxy/filler mixture to the consitency of peanut butter. This filler/expoxy mixture was applied the the shaft pivot area for additional strength. Then again moving the door so the the expoxy would not restrict the door movement at the pivot points.
The fibreglass cloth I had cut out was then coated and applied to both sides of the flapper door. After applying, more expoxy mix was applied to the cloth so that the cloth was saturated and no air bubbles present. Occasional movement of the flapper door ensured that the door was operating to each extreme as designed.
The same procedure was used on the remaining 2 doors. Making sure of the freedom of movement of the flapper doors and the position of the control arms; I let the expoxy harden overnight.
A note on fibreglass resins. Ther are 2 types with somewhat different qualities.. Polyester resins and catalyst is available at most hardware and related stores...some stores will also have fibreglass cloth. Expoxy resin and hardener may be more difficult to finf, but most any boat dealer, parts suppliers will have expoxy and also the silica filler. According to literature and persons in the boat building and repair business; expoy resins are considerably stronger and wiil stick to foreign materials such as steel, fabric much better than the polyester types. However, the expoxy resin does cost about double as compared to polyester.
Another modification I made ( unrelated to the flapper door repairs and modifications). I installed a switch on the dash lip directly inder the blower switch... The wire going to the compressor clutch was diconnected and re-routed the this under dash switch. This enabled complete control of cold air and makes the choice regardless of the control levers....For example, I always use warm, airconditioned air for the defroster .....
Hope this lengthly disertation will be helpful to all that wish to repair. modify their airconditionf system

[Project1970]

Just some added information on my blower switch problems:

*I burned up two switches without ever changing anything else in the system after I started driving my truck. I know for a fact that the first one that burned on me was not the first one that truck had burned!
*After this, it had melted the socket the switch connects to. So I bought a new switch, new pigtail/socket, and a new motor. Burned up two more switches this way.
*I live in AZ, and I'm not a huge stickler for originality so long as it works well and looks at least decent. It meets both requirements for me.

[red71cheyenne]

I'm of about the same opinion as far as the burnt up switch thing goes. Has to be excess current due to the resistor. Its just coild wire. My latest switch is only about 7 months old and is already fried, and in that time I have replaced the blower motor as well. Didn't really find anything wrong with the old motor, but thought I would try it.

Did try something else tonight though, disconnected the resistor and shorted yellow to dark blue. Got high speed at all settings, which makes sense, but my jumper wire immediately started heating up. So what I am thinking is I'll get a controller from radio shack that takes in 12V and distributes it thru a voltage regulator(resistors) out a set of 3 relays. I'll just use the switch to determine which relay recieves the input. Think I will go with the stand alone switch for the a/c compressor like gmc jim does too. I think that will help with the defroster action and will try the collapsible tubing for air routing. I'll get posts this weekend after its all in. Thanks for the comments on the engine and helping with the posts all. Jeff.