Hi

I got my compressor clutch working again after tracking the wires from the harness to the AC hold in relais and rewiring the clutch to the relais. Relais and clutch click & move again as they should.

I however have a AC system modified by the PO: There are 2 maintenance connectors, red and blue on the high pressure and low pressure side as well as something electrical that looks like a sensor or valve to me. Maybe the system is also changed to R134 already

Pics:







Looks similar to a piece in this topic:

https://classicoldsmobile.com/forums...tml#post524791

Can somebody with more AC-experience than me guess what it is?

My guess is that this has to be wired in parallel with the AC clutch. so that it opens as soon as the compressor runs. I'm afraid to switch on the compressor clutch with this being a possibly closed valve and pressure building up.

Any ideas?

 

I'm assuming your car is a 68-70 Cutlass body vehicle so please confirm.

Here is a thread I did on the compressor function and the "Hold In" relay on the passenger side fender and this will give you information on how the original system worked and what I was showing to change the compressor function.

https://classicoldsmobile.com/forums...-function.html

You car has had the original POA valve replaced with a newer style and I cannot speak on what the switch on the newer style valve does. I suspect it may cycle the compressor or render it inoperable if the system pressure gets too low.

Your car has been concerted to R134A based on the red and blue fittings you have. But in order for 134A to stay in the system, you really should change the AC lines to a barrier type AC hose. There are available for a few different sources here in the US. An original POA valve can be adjusted to work with 134A and some have done it themselves or there are companies who will do it. If you want to go back to stock, I have a nice original POA that is clean internally and would be a valve a company would adjust without having to rebuild it first. I've never shipped to Germany so we'd have to figure that out if you were interested.

Brian

 

Sorry, just saw you last line stating your car is a 70 Cutlass so the info I provided would apply.

 

You have a modification that replaces the POA valve with a low pressure cycling valve.

The valve that's supposed to be there opens or closes partially in response to the line pressure, keeping the evaporator pressure correct regardless of temperature and engine speed.

The valve that is there turns a switch on and off, which turns the compressor on an off, regulating the pressure through the compressor. It's the way modern cars regulate their A/C. The switch should be in series with the clutch coil.

The odds are that your system has been converted to R134, but the question is, How well?
For the system to function properly, the condenser (in front of the radiator) must be converted from a "single tube," where one tube snakes back and forth, to a "crossflow," where each side is a sort of a tank, with many tubes connecting between them (sort of like your engine radiator), and the the receiver has to be changed to an R134 receiver, as the materials in an older R12 receiver can disintegrate when used with R134.

You can argue the benefits of the low pressure cycling switch versus the POA valve, but the "best" way is probably to have an original POA valve adjusted for R134, as the function of the low pressure cycling switch is to cycle the clutch on and off over and over again, and the A6 clutch was designed to just turn on and stay on.

Rob has a nice thread on here describing how to readjust the original POA valve for R134.

- Eric
-

 

Seen that thread. But now it's printed & in my pocket for today's session in the garage.

That was an indication for me, being a completely A/C noob.

What I suspected: A half-a**ed conversion. I even don't know if it's filled at all, so I'll take the compressor off the belt and leave the A/C inactive for now.

Thanks, guys!