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I swapped an newer LT1 into my 88 IROC and most everything works. I am attempting to get the AC going but I am running into some problems. I have the Holley Accessory Drive kit with the SD7 compressor. I replaced the evaporator, condenser, orfice tube, and fabricated new lines. Everything seems to work except no cold air at the vents. The dryer and lines coming out of the evaporator are cold. I held a thermometer against the dryer and the temp went down to 45 degrees. I am assuming the system is working as it should. I am wondering if there is a problem with the vent doors. Inside the car, if I move the selector through its paces, the airflow seems correct. With the evaporator, I noticed the old one had screen and some foam around it and the new one does not. Should I remove the evaporator and insulate more? Any other suggestions?
The pressures tell the story. The AC itself (compressor etc.) is working fine. Looks like it's a warm humid day out; probably 90° or a shade more, 60% RH or so.
You have some sort of air direction issue. The ducts under the dash aren't working right in some way.
Never hurts to insulate the evap core better, but I doubt that it'll "fix" whatever is ailing the system.
In my car, the evap housing right above the exhaust manifold, had crystallized and crumbled to dust, leaving a ragged hole about 4" x 5". You might possibly have the same thing in effect.
Yes, the pressures tell the story. It was 90+, humidity was 60+, low pressure lines coming out of the evap were ice cold.
What would you suggest? The area of the evap housing seems to be ok, I had the engine out and cleaned the whole area. I will jack the car back up and check closer. I did have to cut a portion of the housing (golf ball size) that hit the header and I patched it with heat tape. Should I insulate that better? Fiberglass? That would require removing the evaporator. If I do remove the evap, is there anything to see inside that may be messed up?
As for the ducts under the dash, how can I tell if things are messed up? I am pretty sure the controls are directing the air to the right outlets.
I'd suggest looking at the evap housing for damage, as we both mentioned; patching it with something more enduring than tape (I used fiberglass); make sure the evap itself is clean (you can take it out and wash it with soap & water and the hose); seal around it with some sort of foam (go to a place that sells stuff for commercial AC installations and get some of that thick dense black insulating foam they use, maybe ¼" thick or so); make sure all the doors work and that the air is all going the right places. Check particularly that the temp blend door in front of the heater core is closing fully.
The evap housing comes out of the car in its entirety with very little drama. There are about 3 or 4 screws (13mm head I think) on the engine room side across the top and the side, and a similar number under the edge of the carpet in the interior. I think even with the motor in place. Might have to give it some space by loosening the fender. Once it's out, you can split it in half and remove it from the evap coil, without discharging the system. In fact I'm pretty sure that, again with very little drama, you can lift THE ENTIRE AC system out, intact; evap w/ housing, lines, compressor, and condenser (pretty sure that's how it went into the car... fully assembled and charged BEFORE it was installed) and work on it that way. Under the dash is more of a hassle but even that isn't that bad to pull out all the pieces, clean em up, replace any foam or tape or whatever at joints of things, remake door seals, etc.
I was able to figure it out with the help of a youtube video. The video (link below) was from a guy who installed AC in a LS swap. Pretty much what I did, all new stuff. He ended up having the same problem. Temps coming out of the vents was only a little lower then ambient. He figured out that the evaporator needed to be sealed better. I used rubber weatherstripping but the AC now works, maybe not as cold as I like but being 90+ with high humidity, it cooled enough to drive around comfortably. Sure beats taking the dash apart looking for issues there.
07-30-2020, 10:46 AM
