a/c dryer [pressure switch

[kglowacky]

I am trying to figure out why my binary and low oem pressure switches will not turn on my compressor. (Bought one of each to see if either one would work)
Details. 78 Silverado factory a/c set up except changed compressor and condenser to 134. Bought new oem dryer. did change orifice. Can't get compressor to turn on with either the 134 binary switch or the oem 12 switch. I can bypass the switch and the compressor comes on and works great.
a couple questions.
1)there are 2 nipples on the dryer does it matter which one i install the switch on? have tried both switches on both nipples.
2) next there is a removal screw in valve in both nipples do they need to stay in or do I remove the one I have the switch on.

my pressures on my gauges are both in perfect range



UPDATE. After more study it is clear the switch I am trying to use does not match the dryer nipple on my new dryer. I need to either find the correct switch or get a new dryer. Anyone have any idea what switch I need. I bought the dryer on ebay and I cant find my purchase history on what it is for.

uploaded a picture. It looks like the nipple has a piece extending from the end of the threads that is stopping my switch from depressing /engaging the valve. Anyone have a picture of theirs they can share? I threw my old one out.

[Dead Parrot]

The nipples were changed for the switch to R134, probably to limit folks from trying to fill their R134 system with leftover R12. Conversion kits often included modified nipples.

Might need to get a pressure switch for a newer 134 vehicle.

[kglowacky]

I agree
now who can help with the correct switch.

[Just call me Sean]

The nipple stays in so you can change the switch without evacuating the system. 94 truck is the first year with a 134a switch, but the R12 switch should work too. They both have the same threads.

[Hart_Rod]

Originally Posted by just call me sean

the nipple stays in so you can change the switch without evacuating the system. 94 truck is the first year with a 134a switch, but the r12 switch should work too. They both have the same threads.

+1

[87chevy.com]

I have stock 87 aftermarket drier and factory 87 switch. no problems as its designed to open circuit when the pressure gets too low.
trouble shoot.... power goes into low pressure switch, power goes out to compressor... you have added another switch... is it the right switch, try removing it and just jumping those pins to eliminate it and report back

[kglowacky]

been working on it the past couple days. went back to the stock oem r12 switch and it works. my concern is in this old-style system that did not come with a high-pressure switch so what happens if the pressure gets too high. Got all my leaks fixed now the problem is high pressure. My mechanic thinks it is either the orifice meter restricting it or my 2001 camero condenser is restricting my flow. We will figure it out I am going to buy a new condenser. Trying to research what one to get.

[Just call me Sean]

There is a blow off on the back of the compressor for if the pressure gets too high. There is a spot on the back of the compressor for a high pressure cutoff switch if you wanted to add one.

[kglowacky]

there are 2 lines coming off the ac condenser. One is smaller dia then the other , One connects to the compressor the other to the evaporator. Can someone confirm which one the small line connects to and which one the larger in dia, connects to.

Long story short when I had lines made for this the ac the worker told one way to hook it up and the gm picture had it the opposite. The condenser came out of a 2002 Camero.
got a bad feeling I am hooked backwards and that is my high-pressure problem.

[Just call me Sean]

On mine, the larger goes to the compressor, smaller to the evaporator.

[kglowacky]

Thank You that is how mine is hooked up. So next i will disconnect hoses and test for restrictions. Going to pull the orifice and make sure it is installed correctly and the correct color orifice.not sure what color I have but need to confirm correct color and what I have.
I am assuming there isn't a difference if you install it upside down or right side up/ My large line is on the bottom.

[Hart_Rod]

Originally Posted by kglowacky

Thank You that is how mine is hooked up. So next i will disconnect hoses and test for restrictions. Going to pull the orifice and make sure it is installed correctly and the correct color orifice.not sure what color I have but need to confirm correct color and what I have.
I am assuming there isn't a difference if you install it upside down or right side up/ My large line is on the bottom.

Are you running electric fans? Are they coming on when the AC comes on?

[kglowacky]

yes my electric fans are coming on when I turn the a/c on.

Been doing some research I think i installed the orifice in backwards. LOL this is what happens when you are a shade tree mechanic. Going to check tomorrow.

[87chevy.com]

look on the back of the compressor for S and D.... suction and discharge.

suction comes from evaporator
discharge goes to condenser

attached picture found on ebay

[Hart_Rod]

Originally Posted by kglowacky

I am trying to figure out why my binary and low oem pressure switches will not turn on my compressor. (Bought one of each to see if either one would work)
Details. 78 Silverado factory a/c set up except changed compressor and condenser to 134. Bought new oem dryer. did change orifice. Can't get compressor to turn on with either the 134 binary switch or the oem 12 switch. I can bypass the switch and the compressor comes on and works great.
a couple questions.
1)there are 2 nipples on the dryer does it matter which one i install the switch on? have tried both switches on both nipples.
2) next there is a removal screw in valve in both nipples do they need to stay in or do I remove the one I have the switch on.

my pressures on my gauges are both in perfect range



UPDATE. After more study it is clear the switch I am trying to use does not match the dryer nipple on my new dryer. I need to either find the correct switch or get a new dryer. Anyone have any idea what switch I need. I bought the dryer on ebay and I cant find my purchase history on what it is for.

uploaded a picture. It looks like the nipple has a piece extending from the end of the threads that is stopping my switch from depressing /engaging the valve. Anyone have a picture of theirs they can share? I threw my old one out.

What 134A binary switch are you referencing? Where did you get it? Part number? Where is it installed?

[87chevy.com]

man, too many jokes about 2 nipples.. but yes, one is for the switch, and the other is for the r-12 service connection, most have a r-134a adapter installed on it... i forget if the valve stays put in for the r-134a adapter or not, but the one for the switch, yes, it stays put.... id imagine both stay put.... what manufacture puts extra parts on a product anyway..