A/C recharge stumper

[brandonvalentin]

So I'm trying to convert my '88 924S to R134a since all of the refrigerant has long since leaked out (through the high side schrader valve apparently, which I've replaced). New receiver/dryer, new o-rings, new schrader valves, 90deg R12 adapter and R134a quick connect fittings, all installed. I've pulled a vacuum on the system down to -30 inHg, and it held just fine (left the gauges hooked up for an hour while I was eating dinner). Now, when I try to charge it, I cannot get it to take in any freon. Just opening the can and venting into the low side won't even lift the needle off the -30 inHg mark. I turn the car on, jumper the low pressure cut-off switch, and the compressor turns on and spins. Still not sucking in any freon. I know freon is coming out of the can and into the manifold as I can hit the schrader valve on the charging hose and get a spray of refrigerant and see liquid in the sight glass on the gauges.

What am I missing here? It shouldn't take more than 10 minutes for the first can to go in. Can is still pretty heavy as well (compared to another full can). My car has low side filling port on the back of the compressor. Like I said, pulls a vacuum through it fine.

Ideas?

Thanks,

Brandon

[bazar01]

Hook up the high side hose to the high side schrader valve. With the car off, charge a portion of one can of R134A liquid (inverted can) on the high side.
If it goes in, your low side schrader valve is defective, just replace it.

[mattdavis11]

Remove the schrader valve that is on the compressor before the 90, you don't need two. Either that or you didn't twist the knob on the end of the low side hose. You weren't vacuuming anything but the hose.

It will suck in the first can, and I'd charge as gas (can up right). If you do charge as a liquid, you can damage the valves in the compressor.

[John_AZ]

You put in a 90 degree adapter-----WHY? The '88 924S does not need it if OEM (if not modified somehow). MY low side is on the firewall passenger side.

I do not have any trouble getting the hoses to the lines. (The early 944s required the 90 degree under the compressor for access--fyi)

When you put in the 90 degree adapter, did you first remove the origninal schroeder valve before you put on a 90 degree adaper with a 2nd schroeder valve? The new 90 degree adaper may not depress the OEM schroeder valve.

Another guess may be a clogged expansion valve.

GL
John

[brandonvalentin]

mattdavis and John_AZ: I did indeed remove the original low side schrader valve before installing the 90 deg adapter as I knew the adapter wouldn't depress it. The adapter has its own schrader valve on the end. Also, the low side service valve on the hose *is* open (and I've tested it by shooting a little refrigerant out of the end of it).

John_AZ: my 924S does not have another low side fitting anywhere, I've traced the entire AC system. The low side port on the compressor is *it*. With an R134a adapter installed the port is too close to the alternator mounting bracket to get an R134a-style quick coupler over it, hence the 90 deg adapter.

I may just buy some R12 hoses for my manifold gauge set, remove all of the conversion parts, and go directly into the original fittings (after putting in a new low side schrader valve of course). Might be easier to eliminate the adapters as variables.

Thanks,

Brandon

[brandonvalentin]

Thanks everyone who responded. I did get the system charged. I tore the low side apart again, put it back together, vacuumed it again, and it charged. Go figure. But now, it's cold enough to make me uncomfortable at full blast. =)

[mattdavis11]

Run the fan on a lower speed so the compressor cycles, just as it should. High fan does 2 things, the life of the fan decreases, and the common assumption to "switch it on high" right off the bat doesn't allow the evaporator to chill. What happens instead is you ram 110 degree air at full blast across the evaporator, the compressor doesn't like it.