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Discussion Starter · #1 ·
Hey Guys, It's 80+ here in KS today so took the 66 out for a fun drive, after having the car sit out in the sun with the windows up it was hot inside and decided to try the AC on the way home (15 miles). I put her on cool/recirculate and the fan on high. It started blowing the air and got colder as the miles went on but I never felt the compressor kick on or off but it certainly got colder after 10 miles. When I got home I opened the hood and noticed the AC clutch was turning and there was some frost on one of the lines. If I'm not mistaken that center part of the AC pulley is the clutch right? Well it was turning for sure but I don't understand why it wasn't kicking on and off because we all know when an old York compressors kicks on and off you feel it.

I also looked for condensation dripping under the car but I'm sure not enough built up to drain.

Am I just making a mountain out of nothing right now?
 

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The expansion valve may be malfunctioning. This can cause high pressures and freezing up of the evaporate. Check your system with gages while running. Water is a direct result of the humidity and if you are not getting any and it is a humid day check the drain hose for being blocked. Mud Dabbers,ants, spiders like to nest in those tubes.
Do not allow water to build up in the heater box as it will eventually spill onto the floor. Water not draining can become a huge stink as it starts to mold in the heater box.
Mike
 

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Discussion Starter · #4 ·
I'll check that switch and get some shop to check the system while it's running but maybe this might be the problem. The cable that's for switching over to Heat/Cold got a kink in it awhile back and I tried to straighten it and hoped for the best. So when it was time to move the switch over to cold I did it real slow and maybe it didn't engage all the way? I know there's a switch that it engages way under the dash and if I'm not mistaken it's to turn on the compressor?

AFX.....I hope to shout your wrong about that expansion valve, I had that replaced years ago. I've got 9 cans of R12 left and wasn't planning on using them to recharge the system if need be. I know of one place here in town that will evacuate the system and replace the valve but there always seems to be issues. Like more R12 is needed.

I don't know what would be involved if I switch over to R134 later but since I have the R12 I'm going to use it.
 

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I'll check that switch and get some shop to check the system while it's running but maybe this might be the problem. The cable that's for switching over to Heat/Cold got a kink in it awhile back and I tried to straighten it and hoped for the best. So when it was time to move the switch over to cold I did it real slow and maybe it didn't engage all the way? I know there's a switch that it engages way under the dash and if I'm not mistaken it's to turn on the compressor?

AFX.....I hope to shout your wrong about that expansion valve, I had that replaced years ago. I've got 9 cans of R12 left and wasn't planning on using them to recharge the system if need be. I know of one place here in town that will evacuate the system and replace the valve but there always seems to be issues. Like more R12 is needed.

I don't know what would be involved if I switch over to R134 later but since I have the R12 I'm going to use it.
If you have an expansion valve you dont have a cycling switch. I would say it is working fine.
 

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... When I got home I opened the hood and noticed the AC clutch was turning and there was some frost on one of the lines. ...
This is the only thing that grabs me - the low-pressure (larger outlet side) line of the evaporator may get cold and sweaty with condensation, but you shouldn't see frost on either line unless the pressures are off. Frost on the high side (smaller inlet side) line means low pressure, and on the low side line means over-pressure. It can be from under/over-charge, or a bad metering valve. I'd throw the gauges on it for a quick check.

Also, did you get water draining after shutdown? That would indicate the evaporator is freezing the condensation, and the ice block melts after sitting a while. If run long enough the ice blocks the air flow so the vent airflow output gets less and less as time passes. Just some clues.

David
 

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Discussion Starter · #7 ·
David, I called my AC mechanic and he said 15-10 miles of use in only 80 to 84 degrees wouldn't let any condensation build up since there was next to no humidty and he also said it wouldn't need to cycle since it's not working hard due to the temp outside.

About that line freezing, it was only the fitting and it was the big line. So if your right David then the low side is over charging, I think I'll have my mechanic check it with the gages and hope for the best.

Is the metering valve the same as the evaporator valve?
 

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Don't know if your setup is like mine. My Your wouldn't stop running so I replaced the thermostatic switch broke and I think also around the same time I replaced the evaporator sender. Those parts were like $40 each. You need to reuse the thermostatic switch bracket if you get a new one.
 

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Is the metering valve the same as the evaporator valve?
Most commonly called an expansion valve, metering valve, orifice or orifice tube. All the same thing for the little gizmo that releases the high-pressure refrigerant into the evaporator at the correct rate for the type of refrigerant. They are designed for specific refrigerants and their properties. While the "wrong" one will still work, it will not be tuned to the system, and performance will suffer. This is a common reason why conversions often do not cool as well, though most of the issue can be masked by playing with the pressures for best effect. Likewise, the correct valve can cool too much (evap freezing) or too little (warm air) if the pressures are off. A common sign of possible pressure or valve issues is line frosting after the valve, or after the evaporator.

David
 
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