Working AC again

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Full Access Member
May 14, 2012
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First Name
Truck Year
1985 , 2004
Truck Model
k-1500, 2500 HD
Engine Size
350, 6.7
Like the title states I have working AC after not having it for over a year. This problem started with a leaking Schrader valve on the small dia. tubing running from the condenser to the evap. I broke the tubing trying to replace the valve. I then ordered the wrong tubing from a local parts store. LMC had the correct part. Before replacing the tubing, I thought it would be a good idea to check the orifice tube. Wrong again. It broke off in the evap. I drilled it out and ran a screw into it so I could remove it without damaging the evap. The orifice pulled out in pieces. I had to run the screw in each time to get more of it out. That left me thinking if I got it all.

I just figured I would RUN IT. I closed up the system and pulled a vacuum on it. All seemed good till I tried to fill it up with 134. The system would not take an ounce. I replaced the dryer, blew air through the system etc. I fought this for several days and just plain gave up. The AC system on the truck except for the condenser may have been OEM. I had replaced the cond. about 12 years ago when it got damaged replacing the engine.
What to do? I ordered all new parts.

The Ac never blew through the vents correctly. I looked into repairing the problem while I waited on parts. I had duct taped the heater vent on the floor to try and get some flow through the vents. I found that the main vacuum line running from the engine had been cut. The actuators were not getting a signal to operate. I ran a new line from the engine. The switching valve on the HVAC control unit had a leak also, it was not in the best shape. I bought a new GM nos control unit, guess what they don't come with the plastic valve. I couldn't find a new one online. I did find one at the salvage yard it was a little more pliable than the old one. With the leaks fixed the system switched like it should. Except for the defrost mode. There's always a catch.

I also found an Evap cover that was only broken in half. When I took mine apart it came out in 3 pieces. I guess the engine side of the fiber glass cover takes a beating from the engine heat. I glassed up my new used cover and put on when the new Evap arrived. I sealed it up with some RTV and foam pipe insulation where the tubing connections protrude out. It looks a lot better than the globs of RTV and plumbers' putty that was there before.

I also found a vacuum actuator in the cowling area broken. The door was broken but he vacuum motor was ok. glued the door and reinforced it with duct tape. I would like to find some new ones or a least a non-broken used one. I guess they want us to buy an aftermarket HVAC system.

By now summer had come to Texas, last May we had some 100-degree days. I stopped working on the 85 and drove my newer truck.
Like most people I put stuff. I didn't need AC during the winter. I fixed and replaced a bunch of suspension parts. This past weekend I finished up replacing the AC parts, compressor, condenser, the flex lines and even the pesky orifice tube. I went with the severe duty red one from GM. All is well just in time for summer. It's blowing me out of the truck. I'll see how it does in August. Just ranting here, a bit. This makes the truck so much better to drive. It also adds a lot of value to it here in Texas. If I needed to sell it.

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