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Expansion valve hiss and pressure switch

agruenberg on Tue June 02, 2009 9:27 AM User is offline

Year: 1992
Make: Volvo
Model: 240
Engine Size: 1.6L
Refrigerant Type: 134a

For a couple of weeks, the expansion valve would hiss after I shut off the engine. Now, the low pressure switch on the accumulator is not cycling the compressor on (the compressor runs fine if I jump the leads). When I jump the leads, the air gets quite cold, and the acculumator also gets cold.

This is on a 1992 Volvo 240 refitted for 134a.

Do I assume I just have a bad pressure switch, or is there something else I should check?

Also, when I replace the switch, do I need add oil?

mk378 on Tue June 02, 2009 10:29 AM User is offline

Sounds like you have a CCOT system since there's an accumulator on the low side. On American cars with these you can unscrew the switch and replace it with the system still charged, as there is a valve under the switch to keep refrigerant from escaping. Not sure about Volvo, though it looks like they're using GM parts.

As it runs cold with the switch jumped, all you need is a new switch.

agruenberg on Tue June 02, 2009 12:46 PM User is offline

Thanks for the reassurance!

I will have to recharge the system; I unscrewed the switch a bit to see if coolant escaped, and it did. So, I'll be devoting much of an afternoon to it.

Alphaman on Tue June 02, 2009 2:43 PM User is offline

Quote
Originally posted by: agruenberg
Thanks for the reassurance!



I will have to recharge the system; I unscrewed the switch a bit to see if coolant escaped, and it did. So, I'll be devoting much of an afternoon to it.

You meant r-134a?

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