A/C Compressor replaced, icing over

[lschafroth]

I have a 2003 Envoy SLT. I replaced the A/C compressor when the factory one ground itself to death.
I have a evacuation pump that hooks to my compressor that has worked in the past.

I replaced the Dryer/Accumulator and the Orifice tube. The accumulator and the lines from the compressor will freeze over. Lots of ice will build up unless we manually turn off the air at times. I read this can be a plugged orifice tube. I took it apart again and it was plugged with debris. I flushed the system again and recharged it and it still does it.

The evacuation pump does not sound like it used to. Sounds more like the air from the compressor is going right through it. Doesnt have that suction sound it used it. Would the system freeze over like that if the system is not vacuumed properly? I'm wondering if the pump is working at all anymore.

Thoughts?

 

[budwich]

I think you have a major problem. A vacuum pump is going to only evacuate air... not lumps, that's actually going to kill the pump AND likely the new compressor. I think you need to disconnect things and do "flushing" (lots) to get rid of any "debris" totally before you connect things back up.

 

[jimmyjam]

when you vacuumed it, did leave it and verify it held vacuum? it sounds like you didn't use a set of gauges on it, just hooked it up directly. How much R134 did you add? oil?

 

[AbsoluteZero]

Sounds like his evacuation "pump" is one of those units that uses compressed air that pulls a vacuum by moving air thru a venturi. Like this: Air Operated Vacuum Pump 4.2CFM AC Refrigerant/Freon Charging Pumps 180PSI 28.3" - Amazon.com

If your old compressor shattered debris thru the system, budwich's advice is a must. There are flushing kits available to do this. In fact compressor warranty depends on flushing the system with some approved/documented method.
Also I think a set of gauges is also a must. The system is cycled on/off as determined by the switch on the side of the receiver/dehydrator so you need to know what low side pressure the system is seeing...
and lastly after doing a complete flush you might consider installing a line filter to catch anything not flushed out.... similar to this one ACDelco 15-10413 Filter : Amazon.com : Automotive

A couple summer's ago I replaced a leaking high pressure line on my 95 S10. No compressor failure however. The repair included a new orifice tube and rec/dehydr. and a fresh charge of oil.... so I decided to give her a good flushing out as a bonus so I made this:
Can't recall but I think the PVC tube was 1 1/2" and about a foot long. I filled the tube thru the fill plug with low odor mineral spirits and used about 50 psi pressure to force thru the system. Did it a couple times on each major component except the compressor.

 

[lschafroth]

A couple summer's ago I replaced a leaking high pressure line on my 95 S10. No compressor failure however. The repair included a new orifice tube and rec/dehydr. and a fresh charge of oil.... so I decided to give her a good flushing out as a bonus so I made this:
Can't recall but I think the PVC tube was 1 1/2" and about a foot long. I filled the tube thru the fill plug with low odor mineral spirits and used about 50 psi pressure to force thru the system. Did it a couple times on each major component except the compressor.

I didnt use a tool like that but I did flush the system twice. I've done two systems like this before and they were smooth. This one has been a pain. I dont have any gauges so I will have a shop pull out the refrigerant and do it again for me this time. The first compressor did not ruin itself internally. The bearing and the clutch chewed itself up so bad it burnt through the wires connected to it and was throwing sparks when the belt turned. I bypassed it with a shorter belt and drove it home because they never EVER break down in town or near home. lol

 

[AbsoluteZero]

OK I just assumed from your original post it was an internal failure plus you found debris in the orifice with the second check. Any case you might check if the switch on the Dryer/Accumulator works. Does the compressor cycle off when unplugged? If the switch stays on the compressor won't cycle. Generally the failure mode is an open switch but maybe debris has plugged the opening so it isn't seeing system pressure. Good luck.

 

[lschafroth]

The switch was replaced before the compressor went bad. The compressor would stop cycling at times and I thought the switch was the culprit. What I didnt know at the time was the wires on the compressor were being warn away with the bad bearing. I'm surprised I never heard it until it finally went.

It has been replaced but that doesnt mean the replacement one is working. How do I test that part?

when I vacuumed the system after a cleaning, I put in the recommended amount of oil and freon. It will freeze you out and works great, but freezes the lines as well. lol

 

[budwich]

I think you underestimate how much "junk" you have in the line. The low pressure switch is just a simple switch... it normally closed (shorted) when things are "good" and open when the pressure drops..... test it accordingly with a meter. BUT from your post, it doesn't sound like you are getting a significant / any cycling so I am not sure why you think your low pressure switch is the issue.

 

[Texan]

The primary reason for pulling a vacuum is to remove moisture (and air). You need to use a "good"
vacuum pump and run it for an hour. Close valve and shut off pump and see if system will hold it's
vacuum for an hour. Then charge system. How you can do this without a good set of gauges is beyond
my understanding.

 

[lschafroth]

Thats why I will have the shop do it this time. I dont have gauges. I dont need the lecture just help. thanks. Hopefully they will get me going again.

 

[AbsoluteZero]

One source said the switch will cycle off at 20 psi and on at 40 psi. Did the AC charging line you used have a gauge integrated with it? . If the compressor is cycling the gauge would tell you the on and off pressures. Again you can check that part of the controls works by unplugging it and verify the compressor shuts off.
Having the shop recharge your system will assure it has the correct amount of refrigerant. I weighed the refrigerant using a postal scale when I did the S10

 

[lschafroth]

One source said the switch will cycle off at 20 psi and on at 40 psi. Did the AC charging line you used have a gauge integrated with it? . If the compressor is cycling the gauge would tell you the on and off pressures. Again you can check that part of the controls works by unplugging it and verify the compressor shuts off.
Having the shop recharge your system will assure it has the correct amount of refrigerant. I weighed the refrigerant using a postal scale when I did the S10

Yes, unplugging it does stop the compressor. I had to do that through the winter so we could use the defrost otherwise it would freeze super fast.

 

[lschafroth]

I had it checked by a mechanic and he adjusted the coolant pressure and it now works without freezing over. I must have had it slightly off.

 

[Blckshdw]

Thanks for coming back and providing an update/solution