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Replacing Low Pressure switch

73Wagoneer on Sun February 28, 2016 6:33 PM User is offline

Year: 2005
Make: W22
Model: RV
Engine Size: 8.1
Refrigerant Type: 134a
Country of Origin: United States

I have an RV, and the compressor does not engage, I put gauges on the system, 90psi on low side, obviously that high, because compressor is not engage.

After looking at all the connection I found that the low pressure switch with is located next to the low pressure gauge connector, to be loose, I disconnected it and both the male pins on the switch are bent over.

So I need to replace this, do I have to evacuate the system before removing switch, or is there a Schrader valve that will stop the 134a from coming out?

Also, would this be my problem for the compressor not engaging? is there a way to bypass just to see if the compressor engages?

GM Tech on Mon February 29, 2016 9:49 AM User is offline

Both pins are bent over- so bend them back straight- use a dental pick. They bend very easily from hap hazard home mechanics not paying attention to connection.

Yes, this would be reason compressor does not come on.

Yes, you can jumper the mating connector with a paper clip to test the system.

Typically, you can remove the switch without de-gassing the system- there is most likely a shrader valve under the switch- if so, there will be a small hiss as you unscrew the first thread or so, then it should stop as the switch backs off and the valve closes- if not, then stop and put it back on and have system evacuated.

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

73Wagoneer on Mon February 29, 2016 6:50 PM User is offline

73Wagoneer on Mon February 29, 2016 6:53 PM User is offline

Thanks for the response.

Tried to bend pins, one broke, got a new one coming in

So I jumpered the low pressure switch, and compressor still will not engage.

Put volt meter on compressor connector, no voltage, fuse and relay are good

Looking for suggestions

mk378 on Mon February 29, 2016 6:59 PM User is offline

Look for a switch or sensor on the high side. You can't jump three-wire sensors, but you can check if left unplugged, bent pins etc.

GM Tech on Mon February 29, 2016 7:21 PM User is offline

Uhm- it may just be your terminology- but you don't jump the switch, you jump the switch connector - at the plug on the end of the wire....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Dougflas on Mon February 29, 2016 7:58 PM User is offline

Hey Guys,

When trying to straighten connector pins, try using the old fashioned mechanical pencil. Run the lead back in and use the opening and place the pin inside. This has saved me many times over the last 30 years or so.

73Wagoneer on Mon February 29, 2016 8:01 PM User is offline

Quote
Originally posted by: GM Tech
Uhm- it may just be your terminology- but you don't jump the switch, you jump the switch connector - at the plug on the end of the wire....

Yes my terminology was wrong, I did jump the connector and the end of the wire and not the switch.

73Wagoneer on Mon February 29, 2016 8:03 PM User is offline

Quote
Originally posted by: mk378
Look for a switch or sensor on the high side. You can't jump three-wire sensors, but you can check if left unplugged, bent pins etc.

yes there is a switch or sensor on the accumulator/drier, I did pull the connector off and everything is fine on this connection

73Wagoneer on Mon February 29, 2016 8:23 PM User is offline


The switch on the accumulator has 2 pins as well, when I jump it, the electric fans will kick in

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