Old Air A/C installation.

[ddsmith]

Several board members requested I post this information here. So here goes. The first part will be a bunch of night time pictures taken of the truck following the installation. I will follow that with the initial information I provided cali_surfer because he wanted some details. I will then provide information specific to the install since it's still relatively fresh in my mind. If you have specific questions that I am not answering then you can PM me and I will do my best at answering to the best of my knowledge. The disclaimer is I have no relationship with Old Air Product other than I purchased on from GMC Paul and this is my experience with it. Let's get started.

Additional photo in the next thread do to number of image limits.

This is exert from the info I sent cali_surfer.

How about I start you off by telling you what you can do even before the unit arrives. Take your glovebox out. If the truck isn't driven daily and you know when the unit will arrive then here are some other great get them out of the way things to do. Remove your heater and ducting on the inside of the truck. Remove all of your duct hoses. You get new ones in the kit. Remove the firewall side ducting/(evap) if the truck originally had A/C. Remove the bumper and grill. Boy it looks funny like that. Remove the heater control panel. You'll need it out for the installation. Remove the cables from the control panel. You sort of need to do this to get the control panel out. Remove the radio to allow access for running duct hoses. Remove ashtray, actually needs to come out for heater control panel removal. I was thinking it probably does not have to come out but hey it four screws.

The only thing you reuse is the control panel and the vent outlets. Everything else is pretty much included. Don't buy anything thinking you may need it because you'll probably be ripping it out. I posed that same question on the board because I was thinking about fixing the hi speed relay and someone replied not to bother. They were right if I had fixed it I would have been throwing money away. All of the vent doors and other stuff related to the original come out with the heater and evap removal with the exception of the damper on the passenger side kick panel and the cowl area on the passenger side. Neither one is needed for the Old Air unit to function. In fact they recommend the doors stay shut to reduce outside air in the cab. The one on the kick panel stays closed without vacuum. Just pull the hose and your set on that one. The one in the cowl area I'm still trying to figure out. I believe it is normally open with no vacuum but can't see it well enough to make sure. I currently have the hose removed from that one also. If it is closed with vacuum it's easy to make it that way with the engine running. Just plug the hose into the fitting were the original vacuum reservoir tapped off the intake manifold. The vacuum can gets removed. It has two lines. One comes from the manifold and one that feed a valve on the A/C and heater control panel. During removal of the panel you will see three vacuum lines hooked up to a three port valve. It doesn't look like a valve but that is what it is. Those hoses get pulled and discarded. The new setup uses two cable controls. One controls the defost damper and one controls the heater flow control valve that they provide in the kit. In addition they provide a cutoff valve to totally stop coolant flow in the summer to prevent defeating your A/C system cooling ability. They provide the new cable so you can scrap the old ones when you pull them out but if your like me you'll keep them until done. You never can tell when they may be useful.
I'll do a quick run through of the installation. The control panel gets modified first. The kit comes with a microswitch which allows the compressor to operate. This gets mounted to the control panel with two screws or pop rivets. The instructions say drill to 1/8 " pilot holes. All I'm going to say is you decide what size holes you need to drill. I ended up using the pop rivets because I don't plan on taking it apart. Just make sure the switch is positioned so that the switch is made up when the control lever (the cold/hot one) is in the cold position. Do not reinstall the control panel. Wait until later when the cables get installed.
I moved then to the unit installation. The A/C and Heater unit is a box with four tubes coming out one side and three nut looking thing installed on that side. There is a plate that goes on the inside of the firewall and a plate that mounts on the outside of the firewall. They eventually get bolted together and sandwich the firewall. Here is were you'll need some kind of cutoff wheel or sawall. The firewall on my truck had a raised lip on the openings on the inside of the firewall. That raised lip has to be removed and some additional material needs removed because it interfers with the tubes that must passed through the firewall. I used a plasma cutter which made it alot easier. The instructions said I would need to enlarge some bolt holes on the firewall and that wasn't necessary. Once the firewall is modified put the inside and outside plates together sandwiching the firewall and check for fit. Pull the inside plate back off and mount the unit to the plate with the three 1/4" X 3/4" bolts provided. Don't overtorque or you'll pull the nuts out. Remount the inside plate and mark the drain location on the floor of the cab below the unit. I had to pull back my floor mat for this. They say to drill a 1 1/4" hole in the floor for the grommet. My grommet was so stretched out because some dummy folded the hose and put it through the grommet streching it out of shape. I chose to drill a hole that was just a small bit larger than the drain tube and seal it with RTV. I'm pretty sure I used a 5/8" drill for this operation. So with the unit out drill the hole. Attach the hose to the unit. You can do this a couple of ways. I chose to attach it to the unit and work it through the firewall during the inside plate reinstall. You could try and put it on after the inside plate is installed with the unit attached but I didn't want the pain. Once the plates are installed( don't forget the ground wire) then move to the outside of the cab.
There is a four hole grommet that needs to go on over the four tubes coming through the firewall and then worked into the engine compartment firewall plate opening. I used dish soap to lubricate it so I could get it over those fittings one at a time. Then I worked it into the opening. Make sure the caps are tight on the A/C lines so you don't get dishsoap in the freon lines. That would be the two on the left looking at the firewall. I think I'll go for now but I'll give you additional installment of the installation. Talk to you later.

I'm editing this to provide some of the stumbling or slow down things that happened in addition to what was already mentioned above and I broke them out so that if you already read above you could just look here.

There was suppose to be a decal that get put on the new control after you modify it to identify what everything does. My kit didn't come with a decal. I figured I don't need it anyways because I know what the levers do. It would sure goof up someone if I let them borrow my truck. Hey wait I don't have to worry about that because no one borrows my truck.
The instructions for inserting the thermostat probe in the evaporator core were confusing. They made a big deal about were on the core to insert the probe and they had a bullseye attached to the core to show where to insert it. The diagram shows the probe going straight in and the instruction said insert it at a 45 degree angle. This is obviously to allow insertion to 2 inches in depth and to not run into an evaporator tube. You'll see when you get there. This can be done as soon as you unpack the unit if you chose.