A/C Low Pressure Switch question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

wlt3355 · 01-10-2017, 02:19 PM

I need to replace the low pressure switch due to carelessness as I broke one of the terminals off doing other work.

Question: When I unscrew this, will I lose Freon? Sorry, in advance if this seems a dumb question.

1972 C10 with Vintage air, switch is on the dryer

67 chevelle · 01-10-2017, 02:29 PM

The system needs to be evacuated , switch replaced , and then refilled

wlt3355 · 01-10-2017, 02:42 PM

My issue...this is actually the only switch I see,

Andy4639 · 01-10-2017, 02:46 PM

that has to come out so yes it needs the be sucked dry and replace and vacuum good then refilled.
Are you sure it's a low pressure side switch. The one I installed on my 64 Impala there was high side pressure switch. It cuts the compressore off if to much pressure is made.

wlt3355 · 01-10-2017, 02:51 PM

I thought I was sure until I looked and did not see anything else, can you tell by the picture?

Andy4639 · 01-10-2017, 02:57 PM

Quote:

Originally Posted by wlt3355

I thought I was sure until I looked and did not see anything else, can you tell by the picture?

The drier is in the high side loop of the system.

wlt3355 · 01-10-2017, 03:00 PM

Thanks again for all of your input, love the pictures

Walter

Andy4639 · 01-10-2017, 03:02 PM

Welcome.

67 chevelle · 01-10-2017, 04:01 PM

Its actually called a trinary switch .
Too high a pressure , it shuts the system down
Too low a pressure , it shuts the system down
Electric Fan Engagement - 254 psi

Andy4639 · 01-10-2017, 05:41 PM

Quote:

Originally Posted by 67 chevelle

Its actually called a trinary switch .
Too high a pressure , it shuts the system down
Too low a pressure , it shuts the system down
Electric Fan Engagement - 254 psi

It's only 2 wires so it a Binary switch. It will only shut the compressor off.

Binary switch function:
http://www.vintageair.com/Instructions2013/904677.pdf

Trinary switch function:
http://www.vintageair.com/Instructions2013/900161.pdf

01-10-2017, 02:19 PM	#1
wlt3355 Registered User Join Date: Dec 2016 Location: Ferris, Tx Posts: 38	A/C Low Pressure Switch question I need to replace the low pressure switch due to carelessness as I broke one of the terminals off doing other work. Question: When I unscrew this, will I lose Freon? Sorry, in advance if this seems a dumb question. 1972 C10 with Vintage air, switch is on the dryer

01-10-2017, 02:29 PM	#2
67 chevelle Registered User Join Date: May 2013 Location: WEST PALM FLORIDA Posts: 1,174	Re: A/C Low Pressure Switch question The system needs to be evacuated , switch replaced , and then refilled __________________ 68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive

01-10-2017, 02:42 PM	#3
wlt3355 Registered User Join Date: Dec 2016 Location: Ferris, Tx Posts: 38	Re: A/C Low Pressure Switch question My issue...this is actually the only switch I see, Attached Images

01-10-2017, 02:46 PM	#4
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: A/C Low Pressure Switch question that has to come out so yes it needs the be sucked dry and replace and vacuum good then refilled. Are you sure it's a low pressure side switch. The one I installed on my 64 Impala there was high side pressure switch. It cuts the compressore off if to much pressure is made. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

01-10-2017, 02:51 PM	#5
wlt3355 Registered User Join Date: Dec 2016 Location: Ferris, Tx Posts: 38	Re: A/C Low Pressure Switch question I thought I was sure until I looked and did not see anything else, can you tell by the picture?

01-10-2017, 03:00 PM	#7
wlt3355 Registered User Join Date: Dec 2016 Location: Ferris, Tx Posts: 38	Re: A/C Low Pressure Switch question Thanks again for all of your input, love the pictures Walter

01-10-2017, 03:02 PM	#8
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: A/C Low Pressure Switch question Welcome. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

01-10-2017, 04:01 PM	#9
67 chevelle Registered User Join Date: May 2013 Location: WEST PALM FLORIDA Posts: 1,174	Re: A/C Low Pressure Switch question Its actually called a trinary switch . Too high a pressure , it shuts the system down Too low a pressure , it shuts the system down Electric Fan Engagement - 254 psi __________________ 68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive



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