Any A/C guys out there?

[LCOX]

I took the denso rotary a/c compressor off my 83 911sc.
- I resealed it and put a new clutch bearing and new shaft seal and all new orings in it
- Today I tried to recharge it with R 134a but after 15 minutes the compressor still hasn't taken any freon in.
The clutch is engaged, temp and fan both to full a/c.
-Ive also idled the engine up to around 2k rpms and the engine lid pulled down low to pull more air in.
- I'm also putting the freon in on the low side port as a gas only tilting the can slightly from the straight up position every few seconds.
- Anyone have ideas here. I've got a feeling that I may have made a mistake I internally taking the compressor all the way apart.

[flyingjay]

If you are using the disposable cans, the can must be inverted.

[patkeefe]

Are you weighing in the charge? I am assuming the R-134a can weighs exactly the same before and after attempting to charge? Also, did you evacuate the system after you rebuilt the compressor?

[GH85Carrera]

From the factory there was never a high or low pressure switch. Obviously your car has been converted to R-134 at some point. If the person that did the conversion put in a pressure switch, your compressor will not turn or compress at all. Are yoy sure the compressor is engaged?

You will need to jumper the switch to make the compressor clutch engage.

[RedCoupe]

Originally Posted by GH85Carrera

From the factory there was never a high or low pressure switch. Obviously your car has been converted to R-134 at some point. If the person that did the conversion put in a pressure switch, your compressor will not turn or compress at all. Are yoy sure the compressor is engaged?

You will need to jumper the switch to make the compressor clutch engage.

The OP said the clutch was engaged, so not a switch issue.

[T77911S]

how do you know its not taking it in,

close the valves on the gauges and see what the pressure is.
"burp" the hose from the can to the gauges. make sure you punctured the can.
you should burp it anyway to get the air out.
you can put the cans in hot water to help empty it.

you should charge it as much as you can with the engine off, then start it.

did you add oil,.

did you pull a vacuum

[LCOX]

Flyingjay: Yes I'm using a disposable can, however the directions said not to invert the can completely. I'm using a small aftermarket hose assembly with gauge that will only fit the low side port.
Patkeefe: No I didn't weigh the can before and after. Haven't pulled vacuum yet. Need to have this done.
GHi85 Carerra. Yes I'm sure the compressor is engaged. I ran 12 volts direct to the compressor hot wire and the clutch engaged with the engine running.
T77911S: I do have a set of gauges but they are for R-12. The hose fittings on these gauges fit the older style threaded ports on the old original York compressors. Are there adaptor fittings available that will allow these gauges to work on the later rotary style compressors?

[eastbay]

Head over to Harbor Freight and pick up a set of 134 gauges and a vacuum pump for cheap. Then start from the beginning.



If you need adapter fittings try your local AC supply house or appliance parts house, they have all that stuff.

[1979-930]

What Easbay said. Did you evacuate the system for several hours first?

[Bucketlist]

Head over to Harbor Freight and pick up a set of 134 gauges and a vacuum pump for cheap. Then start from the beginning.

If you don't want to buy this stuff you can borrow them from Auto Zone free. I did this a few times before finally buying my own from HF. Investing in a 30lb bottle of R134A on ebay can save money and frustration in the long run especially if you start working on other AC systems in the garage like I did.

Here's a link to my old a/c thread:
Retroair complete system in my non a/c car

[GH85Carrera]

Pulling a vacuum first is essential. The moisture in the air can turn to ice and freeze in the expansion valve and clog up everything.

And the only way possible to get a decent charge is to have high and low pressure gauges and know what is really going on.

[rgofast]

You should also replace the receiver drier, and Accurately weigh in the charge.

[Artfrombama]

You must vacuum all the Air out of the system first. 29.5 inches of mercury for at least 30 minutes, longer if you can

[macssc911]

Sounds like your Schrader valve on the suction port access that’s the valve inside of the port may not be depressed, ether the valve has an issue or the hose you are using the stem in the middle is not depressing the valve in the port. The valve can be easily replaced same tool as for a car tire valve
Good luck

[dhanl82]

I would like to return to the earlier question regarding whether it is OK to invert the R134 can while filling. I have read that to introduce the refrigerant in liquid form will damage the compressor.

Thanks

[macssc911]

Not enough in Can to harm compressor if it’s running, don’t know if you are using a set of gauges or just a charged suction side gauge, as you are trying to get into proper charge range on suction side, make sure you drop the hood down so your rear condenser is able to condense under normal operating conditions You should be looking at around 30 psi on low side and 150 - 170 on high or discharge port on compressor. Recommend charging on a warmer day maybe car outside with sun to create the proper load

[dhanl82]

Thanks macssc911 for your reply.

[kuehl]

If you are charging through the suction port, do NOT invert the can.
When the can is inverted (upside down) liquid runs into the compressor and
will wash the refrigerant oil off the internal components, and you could 'liquid slug'
the reed valves inside.

If you are charging through the high side port engine must always
be off and never running, suggest you stay away from high side charging.

After you learn how to pull a vacuum and you pull a good vacuum down near 29.5
inches of mercury (depending upon your above sea level elevation), and you have purged
the system a few times (meaning repeating the process), the system should pull in quite a few ounces on its own,
if you have done a good job at least 12 oz.
on a hot day. The colder it is outside the longer it will take to pull
in the refrigerant from the can.

When you get your clutch to engage on the compressor with the engine running and you want to speed up the process,
rest the refrigerant can in a larger container with hot water to warm up the can (do not use a hair drier, heat gun or torch on the can).

Keep track of how much you put in (read the volume on the can).
Typically for an SC two condenser system, you will have 33 oz R134a min, all depends upon how well of a vacuum you have achieved.

You do your charging at idle, windows up, doors closed, fresh controls
in the dash center to the left, heat box floor controls down, thermostat fully clockwise,
evaporator blower fan speed 2 or 3,...... write down all your observations, keep records.