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AC low pressure switch

yamaman

Member
Joined
Jun 19, 2017
Location
Taiwan
Hello everyone!! My AC compressor clutch wasn?t engaging so I jumped the low pressure switch on my receiver dryer and AC started blowing cold so I know I have refrigerant. But it would only stay on if I push and hold the plug on the switch with force or it would click back off. I?m assuming I have a faulty switch. Can someone be kind enough to give me the part number?? I have searched on the inter web and it shows 1259519 but the picture looks nothing like it...

Also when I replace this switch will I lose any refrigerant?

<a href="http://s44.photobucket.com/user/childofjuly/media/383A1C12-90FD-4966-87E4-039177A12F6D_zpsbovzcd2y.jpg.html" target="_blank"><img src="http://i44.photobucket.com/albums/f12/childofjuly/383A1C12-90FD-4966-87E4-039177A12F6D_zpsbovzcd2y.jpg" border="0" alt=" photo 383A1C12-90FD-4966-87E4-039177A12F6D_zpsbovzcd2y.jpg"></a>
 
I would suggest that you identify the problem rather than start replacing parts.

The low pressure switch is there to protect the compressor when system pressure drops below minimum. That doesn't mean that there is no coolant in the system so you might see some cool air. What is the vent temperature? How does that compare to the specifications? What is the system static pressure?

I am not familiar with these new model Volvo's. Are you R12 or R134a? Nice to put car information in your signature.

Yes, you are going to lose the coolant when you pull the switch.
 
Thanks for the reply TestPoint! My car is a Volvo 240 GLE, it was made October of 1991 and sold as a 1992 model. I have just added the info in my profile. My AC system was converted to R134a by the previous owner, and the AC compressor, condenser and lines was replaced last year.

The AC was working perfectly till yesterday. I have ordered a manifold gauge, so I can't get a low side pressure reading till it arrives. I'm assuming its the low pressure switch because when I wiggle it around or push it in while holding pressure on the plug the clutch would engage and I would get ice cold air out of the vents, and the receiver dryer would be ice cold too.

I have also ordered a Bentley's manual for the 240 but it won't make it to this side of the pond till the 26th of this month so I'm not sure whats the specifications. Anyways, any help would be greatly appreciated!
 
I would suggest that you identify the problem rather than start replacing parts.

The low pressure switch is there to protect the compressor when system pressure drops below minimum. That doesn't mean that there is no coolant in the system so you might see some cool air. What is the vent temperature? How does that compare to the specifications? What is the system static pressure?

I am not familiar with these new model Volvo's. Are you R12 or R134a? Nice to put car information in your signature.

Yes, you are going to lose the coolant when you pull the switch.

No, you are not going to loose the refrigerant when you replace the switch. No more than you would when you attach/detach the system charging fittings. It is the same set up. A schraeder valve is behind that switch. Just unscrew it fast and very little refrigerant will be lost.
 
All the Volvo's I work on loose the gas. At least I gave you a warning.

You are working on the old 240 R-12 systems. The way that pressure switch is set up is different. The low pressure switch screws directly into the dryer. Removing it would allow the entire charge to escape. The 7-9 system allows you to remove the switch with no significant loss of refrigerant.
 
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Hello everyone!! My AC compressor clutch wasn?t engaging so I jumped the low pressure switch on my receiver dryer and AC started blowing cold so I know I have refrigerant. But it would only stay on if I push and hold the plug on the switch with force or it would click back off. I?m assuming I have a faulty switch.
Jumped the switch, or the plug?
I'm assuming its the low pressure switch because when I wiggle it around or push it in while holding pressure on the plug the clutch would engage
Are the terminals in the switch loose and wiggling around? Is the square plastic part the plug attaches to still crimped firmly into the switch, or is it loose? Are the terminals in the switch or the plug corroded?
 
Jumped the switch, or the plug?
Are the terminals in the switch loose and wiggling around? Is the square plastic part the plug attaches to still crimped firmly into the switch, or is it loose? Are the terminals in the switch or the plug corroded?

I pulled the plug off and jumped the plug.

The plug doesn?t fit the switch very tight, without the wire clip it would easily slip off. I have cleaned the contacts off there is no corrosion.
 
I pulled the plug off and jumped the plug.

The plug doesn?t fit the switch very tight, without the wire clip it would easily slip off. I have cleaned the contacts off there is no corrosion.

I think that switch has a screw in the center holding things together.
 
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