AC pressure switch 1975 280z

[Dave WM]

I am considering using a 33318 drier since the supply of 33286 (low intake port) driers is pretty much gone. I got the 33318 on the way but not sure of the correct switch.

FSM says its a high pressure cut off, but I assume a binary would be fine. Any one know of a correct sized switch for the 33318? I got a NOS compressor (SWP) ready to go, have some dye in it now to see if there are any leaks around the condenser. It has a slow leak so will need to deal with it in a few months. I just hope its not leaking at the evap.

My you tube channel is Dave WM

https://www.youtube.com/channel/UCxMsHgfGwCVtyRrqXVtll-g

 

Edited April 8, 2016 by Dave WM

[hr369]

5 hours ago, Dave WM said:

I am considering using a 33318 drier since the supply of 33286 (low intake port) driers is pretty much gone. I got the 33318 on the way but not sure of the correct switch.

FSM says its a high pressure cut off, but I assume a binary would be fine. Any one know of a correct sized switch for the 33318? I got a NOS compressor (SWP) ready to go, have some dye in it now to see if there are any leaks around the condenser. It has a slow leak so will need to deal with it in a few months. I just hope its not leaking at the evap.

My you tube channel is Dave WM

https://www.youtube.com/channel/UCxMsHgfGwCVtyRrqXVtll-g

 

new drier for 75 here msa drier

 

cheap(er) evap here. allows you to use generic easily found ex valve.  ac kits website

 

I believe thats a 3/8" male fitting on the cut out switch but i'm not 100% sure because I don't have a 75. 

Binary switches here ac kits website

I'm not sure what you mean by "not sure of the correct switch"   A high pressure switch is normally closed (always energized) and is a simple circuit to your compressor clutch.

If the connectors are different just splice on some spade connectors if the plug isn't the same as nissan had.

binary switch would be better than having just a high pressure switch that nissan put on there.  BUT,  if you know to turn off the a/c when you suspect its losing freon, you won't burn up the compressor.

 

Edit:  There are 2 wires to the switch. There is no polarity so doesn't matter which wire goes where. It's a 1 wire circuit. It's like an inline fuse.

Edited April 9, 2016 by hr369

[Dave WM]

thanks for those links! that evap looks like a good alternative. The MSA site drier is NLA, the 33318 is cheap and I think the one some of the other z suppliers are using (they mention that you need to move the copper tubing some to make it fit. The question I was having on the switch is the 33318 says a 1/4 npt fitting IIRC, so looking for a switch that fits that, going to be a bit of a crap shoot if I start ordering parts not being able to check fit.

I see a lot of switches on ebay but they often seem to be low pressure cut off, not to easy to find a hi pressure cut off (as noted in the FSM) so the binary is just me looking at what is common (see those a lot). I am just going to wait for the drier to get here and call the link you gave on the switches, see how it goes. I have not installed any of the new parts yet, just looking for the leak. I went out a while ago and found a suspect looking spot (bright bit of dye on condenser) so maybe that is where it is. Thanks again for the help I will keep the group posted on how it turns out.

[hr369]

23 minutes ago, Dave WM said:

 The MSA site drier is NLA, the 33318 is cheap and I think the one some of the other z suppliers are using (they mention that you need to move the copper tubing some to make it fit.

 

You never know with aftermarket stuff. I'de wait until you get the new drier in your hands and take it down to home depot and try npt fittings on it or measure it.

A high pressure switch is more important to have if you're going to choose.

[Dave WM]

1 minute ago, hr369 said:

You never know with aftermarket stuff. I'de wait until you get the new drier in your hands and take it down to home depot and try npt fittings on it or measure it.

A high pressure switch is more important to have if you're going to choose.

Roger that!

[hr369]

temps in the teens on the evap? isn't that a bit undercharged?  you're 150 high side? what was the ambient?

[Dave WM]

75f ambient, 75psi with engine off hi and lo,  running at 1500 rpm max ac I get 150 highside  low 20's on the low side.

Temps I got with IR gun aimed down at the evap coil was in the teens. air temps with a meat thermometer were high 30's

[Dave WM]

I think I feel a video coming on. If for no other reason to let folks hear the sound of the compressor, and let me know if it sounds like its going bad. I have the replacement ready but planned on running this one for a while to see if the dye showed up any more leaks.

[hr369]

 

32 minutes ago, Dave WM said:

I think I feel a video coming on. If for no other reason to let folks hear the sound of the compressor, and let me know if it sounds like its going bad. I have the replacement ready but planned on running this one for a while to see if the dye showed up any more leaks.

 

could also be clutch chatter.  you can spray the clutch with  a little soapy water and see if the sound changes.

or it could be that idler bearing too.

 

You getting frost on the pipe just before the ex valve?

Edited April 9, 2016 by hr369

[Dave WM]

don't know, I did notice the comp feel def had a "tight" spot as I turned it by hand, almost like an old York single cylinder setup, I assume a warble plate should have no real noticeable compression bump to it. all just a guess as I have not removed it.

[hr369]

how about idler bearing?

 

Its the bearing on the a/c belt tensioner.  The grease inside dries out and they start making noise that sounds like the compressor.

Edited April 9, 2016 by hr369

[Dave WM]

video posted