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Just wanted to say hi to everyone.
I have a 1993 Ford Ranger, 4.0, 4x4 standard cab pickup with 120,000 miles on it. Body, Frame, and Engine all seem to be in very good condition, only problem is the AC doesn't work, it has a new ac compressor on it, but when I tried to charge it up, just as the air started to get cold, the high pressure valve popped off, don't know if it's bad or something else is going on with it.
Thanks for the allowing me to join the forum.
Joseph C Burgess
The pressure sensors/switches on AC systems are "hot changeable", this means you can change them without draining the system, if a sensor should fail
So not understanding the question, if a pressure switch "popped off" and you lost fluid/pressure then that fitting is bad
And there are no "Valves" in an AC system, just FYI
AC compressor pressurizes and heats the fluid in the system(high side) as that pressure is released the fluid rapidly cools and returns to the Low side to be re-compressed
The pressure is release thru a small hole called the Orifice tube on Fords
High side sensor is to prevent hoses from blowing off if pressure gets too high
Low side switch, often called Cycling switch, prevents compressor from "running dry" and burning out
When AC is off the pressure in the high and low side equalize, so only when AC compressor is running is there a high and low side
Ok, I'll try to make what I was saying a little clearer. The ac system has a new compressor, installed by previous owner at a local shop right before I bought the truck. When i bought it, the ac clutch did not engage, since I don't have any ac gages I bought the can of freon that has the gage. When I connected it, it showed no pressure at all on the gage. So I proceed to add freon and the compressor started to kick on and off as the pressure on the gage increased as it should. Just when the pressure was getting to the proper range on the gage, I checked the air coming from the vents and it was starting to get cold,, there was a loud pop at the very back of the compressor, I thought a hose had blown, but after checking, I found that all the freon was vented out of the system from what I'm assuming is a high pressure relief Valve mounted directly to the back of the compressor. After all the pressure and freon was released the valve closed and quit venting. Since I don't have the normal ac gages I don't know what the high pressure side was reading. So a few days later I tried again to recharge it. Same thing happened, it vented all the freon and pressure out at the back of the compressor again. I don't know if the valve that's venting the freon and pressure is bad and venting when it shouldn't, or if the pressure was getting too high due to something being bad or plugged in the system making the pressure go too high and triggering the high pressure relief Valve. I'm going to replace the relief Valve, If that doesn't fix the problem, what do I need to replace first, the orifice, I don't even know where that is, the drier, or something else. I'm also going to get a set of gages and a vacuum to pull a vacuum before charging it again. Thanks for you help.
Yes, most likely the high pressure relief valve on compressor has failed, for two reasons
First, it should only release the unsafe high pressure then close, not stay open and release all pressure
Second, the high pressure switch should have turned off the compressor before the high pressure relief valve opened
On days with 110degF outside temps the high pressure side can reach 350psi, in normal operation
So the high pressure relief valve would be rated at 400psi at least, could be 350psi, but was it 110degF when you were adding freon?
Since this is a "new" system to you, its possible there is a partial blockage on the High side causing the pressure at the compressor to go too high so the high gauge never sees the overly high pressure, long shot
But it still shouldn't have released all the fluid
04-04-2024
