AC Compressor “short cycling”

[Mj2545]

Hey,

 

having a issue with ac components. Today i replaced the ac compressor due to a slight grinding noise within the compressor. After changing the pump, took my truck to a shop to have it vacuumed and recharged properly. 

 

They tried to recharge the system but it did not work. The compressor and lines accepted all the nessessary R134a needed. (0.90 kg) or 32oz. The compressor started to short cycle, acting like it was low on refrigerant. Started paying attention the the low and high side gauges and immediately noticed something was wrong. Low side, started around 50-55 and drops to 20 under clutch engagement. At the same time, high side, started around 220-240 and spikes to 450+

 

My understanding is that the system is over pressurizing the high side. 

I’m thinking of a blockage somewhere? But idk. 

 

Since ive already replaced the compressor, also which I filled to the 8oz. oil specifications. I ordered new high and low side lines and a new accumulator. Hoping that the blockage is in the orifice tube or small screen and the other pieces for safe measure. 

 

Any recommendations, maybe just try to replace the liquid line first? I’d like to replace as little as possible and return what I don’t need. 

Thanks

[Ed ke6bnl]

If the condesor is not hot with that pressure seem like air/moisture is still in the system, and not evacuated enough

[Mopar1973Man]

The orifice tube is plugged. When the compressor is replaced the orifice tuber and the accumulator have to be changed. If there is black death in the system you have to flush the entire system clean. You'll most likely go back and have everything replaced again.

[Mj2545]

42 minutes ago, Mopar1973Man said:

The orifice tube is plugged. When the compressor is replaced the orifice tuber and the accumulator have to be changed. If there is black death in the system you have to flush the entire system clean. You'll most likely go back and have everything replaced again.

 

The orifice tube is located on the low side correct? The solid line that runs between the accumulator and front condenser?

 

I will check this afternoon. I haven’t turned on the ac besides having the shop try to charge the system, I’ll keep it off until the other parts are replaced. 

Thabks 

[Mopar1973Man]

1 minute ago, Mj2545 said:

The orifice tube is located on the low side correct?

 

High side after the condenser along the fender the entire tube from the evaporator to the condenser is the orifice tube. 

[Mj2545]

13 minutes ago, Mopar1973Man said:

 

High side after the condenser along the fender the entire tube from the evaporator to the condenser is the orifice tube. 

Yes sorry. Get them confused. 

Thanks for the reply. Parts should be here today. 

[dripley]

Can too much oil do this? The reason i ask is when i replaced my compressor i did not replace the accumulator or the condensor and i was under the impression that the sytem itself would account for 4 or so ounces of oil. So I drained the new one and only put 4 ounces back in it. My compressor had not failed but clutch was FUBAR.

 

I noticed that the OP had put 8 ounces in his compressor at install.

[Mj2545]

As far as I understood. I filled my compressor to 8oz. Under the impression that the compressor oil is in a separate chamber within the unit. Not mixed with the 134a

[dripley]

I am definitely not the expert on this but thought it was good question since we seem to be operating under different assumptions. I know to much oil will affect the performance of the system. I just dont remember the symptoms of to much oil. Some one will straighten us out though.

[IBMobile]

It is necessary when replacing an AC compressor the oil in the old compressor needs to be drained, measured and noted.   

The oil in the new compressor is then drained.  The noted amount of oil is add back into the new compressor.

 

Location of orifice tube.  

 

[Mopar1973Man]

Oil is driven with Freon throughout the system so yes excessive oil can cause issues too typically blowing out the back of the compressor through the blow off valve.

[Ed ke6bnl]

1 hour ago, IBMobile said:

It is necessary when replacing an AC compressor the oil in the old compressor needs to be drained, measured and noted.   

The oil in the new compressor is then drained.  The noted amount of oil is add back into the new compressor.

 

Location of orifice tube.  

 

A portion of the oil circulates through the system

 

[Mj2545]

I was in a weird spot with my oil level. I checked the old compressor and it was completely empty, so I made the decision to add the entire 8oz. Also had the system evacuated and pumped before removal 

 

hopefully ita not overfilled now 

[Mj2545]

Thanks everyone. 

 

All revommended parts were replaced and is working properly now. 

[dripley]

Good to hear. Just did the wife's saturn with all new parts and it was succesful also. I just wish I had the room in that as I do in the Dodge.

Edited August 26, 2018 by dripley

[Royal Squire]

@dripley are the back of your hands and your arms all scratched up? 

[dripley]

My hands are fair but i did draw a little blood on one of my arms. Not to bad considering where i had them. No busted knucles though.

Also, no leftover or missing bolts. I am pretty god at loosing one now and again.

[Royal Squire]

It seems my skin is paper thin these days 

[dripley]

Mine is too. Started noticing that in my late 50's. But I was working on a plastic car.

[IBMobile]

   

27 minutes ago, Royal Squire said:

It seems my skin is paper thin these days

                               I hear that's what happens to old people.