CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Does a "40" on a pressure switch mean it cuts off when the pressure is lower than 40 PSI?
- Thread starter clutch2k3
- Start date
ugh. got stuck open again today and I had to mess with the screw again to close the circuit.
Replacing the presure switch requires recovering existing refridgerant, vacuuming and recharging, correct?
... and while you're doing that, it wouldn't make sense to not replace the original noisy compressor, dryer, orifice, o-rings, and oil, correct?
Replacing the presure switch requires recovering existing refridgerant, vacuuming and recharging, correct?
... and while you're doing that, it wouldn't make sense to not replace the original noisy compressor, dryer, orifice, o-rings, and oil, correct?
The pressure switch can be removed without venting refrigerant. There is a schrader valve behind it (although it's possible for the valve to be bad). I use a stock R12 switch with R134 or hydrocarbons just by adjusting the switch to cut off just above freezing. The problem is that these switches get old and develop high enough resistance they don't pull the clutch in. This can be remedied by adding a relay - the switch can still pull the relay in and lasts pretty much forever with that small load on it.
40psi is going to be kind of high (around 44F). Your sweet spot is probably closer to 30. I don't know what 40 means molded on the switch.
40psi is going to be kind of high (around 44F). Your sweet spot is probably closer to 30. I don't know what 40 means molded on the switch.
@Blue85 you're my savior.
I've read about the details of this process elsewhere. As I understand it, the focus should be on not freezing up the evaporator instead of achieving a minimum specific low side pressure. I read the goal should be minimum 38° F out of center vent.
@Blue85 did you add a relay to yours?
Yes, AFAIK, the switch on mine is original from 1985. I was adding an electrical center anyway for an EFI conversion, so I used factory blade-type diodes to turn on the fan relays at the same time it turns on the compressor clutch. That means it's been running like this since 2006. But of course a single stand-alone relay could also be used, maybe tap into the power for the blower motor? I may have done that previously.
I too run a relay, with its own dedicated diode soldered in.
Similar to this diagram the 5v can be 12v and that will the original power wire to compressor coil.
Similar to this diagram the 5v can be 12v and that will the original power wire to compressor coil.
Its AC weather in FL nowSeems weird to talk about A/C work. I just had the snowmobiles out a couple of days ago and I've got firewood burning right now.
Im too lazy for that. I'd rather replace it again for $12 the next time it breaks.
I went through 2 clutches and coils, and 1 whole compressor, until I went with the relay.
What?!?!
yep the relay can supply much more current to keep the coil magnet well energized. I used larger gauge wire. Before the disc was slipping to much creating extra heat, and melted well the whole front of compressor, seal, disc to shaft, was a mess.
about how many amps does the clutch draw?
Good question I never have measured it, the fuse is 20 amp. most of the A6 compressors also had a thermal limiting fuse.
The easiest answer is to measure the voltage across the clutch when it's supposed to be engaged. You have the bulkhead connector (×2), the dash selector switch, the pressure switch and all of the factory wiring, so we can't predict exactly what voltage drop you'll see.
Yeah all those connections add up. By the time the current gets to the clutch the resistance from all those connections has cut the available amperage down, to the point it can't close the clutch reliably. With the relay 4 connections, with heavier ga wire provides plenty of amperage, to run the coil.
The old wire to the coil is the relay trigger wire.
The old wire to the coil is the relay trigger wire.
Pretty much any automotive relay will work and the wire size that's already there isn't too bad because you'll have meters less of it. If you're cutting the wires, you can just re-use the green wire and then all you need is a power feed wire. If you want to go all out, just bump the wire up 1 size from stock. According to this link, expect like 3-6A:
https://www.freeasestudyguides.com/ac-clutch-coil-test.html
https://www.freeasestudyguides.com/ac-clutch-coil-test.html
Nice! Thanks! In that case I already have stuff laying around to do this
