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I was trying to diagnose why the compressor won't engage on the factory a/c. Since there is no freon in the system it obviously has a leak.
I did find a light green wire that is hanging loose and taped over behind the cover in the passenger wheel well, the wire hanging down is the one I'm talking about. The other light green wire connects to the outside of something on the evaporator housing behind the wheel well in the engine compartment. Sorry I don't know all the smaller component names for the a/c system. In fact, what are the wires connected to in this picture?
Also since the freon has leaked out of the system, where is the low pressure fuse located? Or does a 73 even have a fuse? Thanks for the help!
I could but it really wouldn't show anything other than more of the wheel well. The opening in the photo above is only about 2"x2", everything you see in the photo around the opening is the wheel well itself. The wire terminates just outside the picture frame, nothing else to see there.
I have a 73 with factory air and I have never seen that box. The plug looks like it’s going to a VIR. The previous owners may have Chan some of the AC sensirs.
Here's a picture with cover ( box) in place. It's in the passenger-side, front wheel well directly behind the wheel. If it or the wheel were any larger, I'm sure they would touch when the suspension is compressed.
Here is a picture of a 1973 factory wheel well behind the pass tire. What you have is a Bubba mod covered up with a cover from a voltage regulator, in other words a complete butcher job.
why the compressor won't engage on the factory a/c. Since there is no freon in the system it obviously has a leak.
The AC compressor will not engage if there is no freon in the system, there is a heatsink in the system at the back of the A6 compressor and a thermal limit fuse mounted on the pass side back by the evaporator housing that prevent this.
Post some pictures of your AC system so we can get a feel of what you're working with. The first thing to do is pull a vacuum on the system to see where you stand in the way of a leak.
Here is a picture of a 1973 factory wheel well behind the pass tire. What you have is a Bubba mod covered up with a cover from a voltage regulator, in other words a complete butcher job.
Dang, I wish they had a Bubba emoji! I could certainly use it for this car! There are quite a few things on it that have "bubba" written all over it. At some point someone had actually done a decent job of fixing/restoring it, but then I think Bubba got ahold of it after that.
The AC compressor will not engage if there is no freon in the system, there is a heatsink in the system at the back of the A6 compressor and a thermal limit fuse mounted on the pass side back by the evaporator housing that prevent this.
Post some pictures of your AC system so we can get a feel of what you're working with. The first thing to do is pull a vacuum on the system to see where you stand in the way of a leak.
I get some more pics of the area by the desiccant cannister/VIR/expansion valve. I'm wondering if someone might have upgraded it at some point because of the mystery cover and wires extending into the wheel well.
Hopefully someone can point out where the fuse is because I'm not seeing it..
From my internet travels as the Superheat Switch (Low Pressure Switch) and Thermal Limit Fuse work on a 73 Corvette.
The superheat switch is normally open, closing at approx 1-5 PSI, which causes a short to the slow acting (the resistor) fuse (Thermal Limit Fuse), normally with three terminals. The slow acting feature allows the fuse to withstand momentary surges of current (caused by momentary closing of the switch) without opening the circuit. The superheat switch senses compressor return (suction, low side) pressure through the large hole in the center of the switch port. The switch/fuse circuit is designed to prevent compressor failure when the refrigerant and oil return is low.
The superheat switch/fuse system originated on GM vehicles in the early 1970s, to prevent compressor failure when 1) the VIR expansion valve or POA valve sticks closed, starving the compressor's moving parts of lubrication or 2) low refrigerant due to a leak causes oil starvation. The addition of this safety circuit substantially reduced the frequency of compressor replacement.
It is necessary to remove the 3 prong Thermal Limit Fuse and jumper the circuit during system charging, till lower than normal suction side pressures are raised by a full charge.
Thanks for all the help!
It does not appear that I have a thermal limiting fuse. At least not in a place that I can find and it is not where yours is located Mr. D.
Here r some more pics, as as I can get without tearing into anything right now. Let me know if there are any areas you want me to get more shots of. Closer image from the wheel well Where the ther al limiter fuse should be, but isn't Under the fender, above fan motor Looking down from edge of fender Looking thru vent behind the wheel Looking thru vent behind the wheel
The VIR has been removed and replaced with a VIR Eliminator, the hoses are 1974 from the looks of the charging fittings, the AC compressor is not 73 OEM, AC wiring on the car has been modified. You need to start with sorting out the wiring using the OEM wiring diagram and the VIR Eliminator install instructions to ensure everything is as it should be.
The VIR has been removed and replaced with a VIR Eliminator, the hoses are 1974 from the looks of the charging fittings, the AC compressor is not 73 OEM, AC wiring on the car has been modified. You need to start with sorting out the wiring using the OEM wiring diagram and the VIR Eliminator install instructions to ensure everything is as it should be.
I was beginning to wonder if this was the case. Then this has a pressure switch instead of a fuse, right? Is that what's behind the wheel well box with the two light green and one black wire? The VIR eliminators I've seen online all have only a single green wire from the looks of it. Did they use to have two and a black? Maybe since the VIR Eliminator and hoses are from a later year that's why it doesn't fit and Bubba cut a hole
I wouldn't doubt that everything is from a different year. The engine is actually from a 1978/79 C/K- 20 pickup and I'm not even sure if anything has been modified on it or not.
Hard to say for sure what you have without putting hands on all this due the multitude of Bubba modifications you have going on. I have no clue what is going on or why it's going on in that wheel well.
Hard to say for sure what you have without putting hands on all this due the multitude of Bubba modifications you have going on. I have no clue what is going on or why it's going on in that wheel well.
Hey come on out the weather is beautiful here! Would love to someone knowledgeable show me how to get it going! It's only about 3,000 'ish miles, sounds like a great road trip!
Yes, Bubba had way too much time working on this car. There are all sorts of dead-end wires in the engine bay, it will take a while to figure it all out, but at least it runs and it's slowly getting cleaned up and restored/presentable. Is it perfect? No, but other than things like this it's in realitively good shape.
If you or anyone else thinks of anything, please let me know! Thanks for the help so far!
Tom
Troubleshooting 1973 a/c compressor
