A/C Clutch Cycling Switch ?

[dsa87gn]

My AC didn't work for many years, so 2 years ago I got a set of R134A conversion fittings, some R134a, dye kit, guage etc and charged it up. I had planned on a full conversion but there was still some pressure in the system. After charging & adding dye I found a tiny hole in the condenser behind the grill. I used a high mileage R134a conversion kit with stop leak/ester oil that claimed it was system safe. AC has been fine 2+ summers.

Last week or two when driving it will suddenly start blowing warm air. Sometimes it will again start blowing cold again.
If I jump the switch terminals on the cycling switch it will kick the compressor on and start blowing cold again.
I have ~35psi on the low pressure side. Also noticed when it stops, if I tap on the switch with a screwdriver it will kick on again.

Bad Clutch Cycling Switch ? Do these go bad ? Does the Leak stop cause issues like this ?

 

[ScottHeidinger]

Common for low pressure switch on receiver/drier to go bad. Easy to replace without losing charge. I wouldn’t use stop leak, I would fix the problem but if it’s charged and not leaking after 2 years replace the low pressure switch and call it a day.


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[BobbyBuick]

Surface tension on the connector is common also use a pick to expand the spring tension of the connector and bend the taps out slightly see if that fixes the problem if not a bad switch

 

[wdxwrx]

That pressure switch went bad on my T-Type in 1992.
As mentioned, it's a snap to change.

 

[dsa87gn]

OK I ordered a new switch but im confused on how the ON/OFF pressures are listed on these things.
A R134a switch has an ON @ 42PSI, OFF @ 21PSI.
If my low side pressure is 35PSI will this thing ever switch on ?

I read on the board lower pressure = colder temps and many recommend the low side pressure even lower than 35.
So I'm confused how the switch would activate the clutch at these lower pressures if its lower than the ON psi.

 

[ScottHeidinger]

The switch should work fine. The stock ones are adjustable and I would think the new ones would be adjustable also but you should be fine at 21 psi.


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[ScottHeidinger]

Stock adjustable screw


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[salvageV6]

Part stores used to sell replacement134 pre-set switches for GM cars that were set a couple of psi. lower than the factory switch, which as mentioned and shown above is adjustable.

 

[dsa87gn]

Replaced the swich and all seems good so far. I ended up with an R12 switch with a turn off of 24PSI.
I did adjust the screw 1/4 turn CCW to lower the pressure.