2002 Impreza Ac Compressor Low pressure return line Frost coated?

[lmdew]

2002 Impreza, the compressor had locked up, so I put a used one in. 

It worked fine for a few weeks.  Then the AC stopped blowing cold air after 30 minutes of use.

High pressure line leaking.  I changed it with the one off my 2005 Impreza.  I change the o-rings, Compressor and Condenser.

I had a service center pull a vacuum and service it.  It worked fine for about 30 minutes and then stopped blowing cold.

The Low pressure return line was frosted up again.

Evaporator?

So goes the island beater.

Thanks,

Larry

[el_freddo]

Sounds like an issue where the evaporator is frozen over, which could point to the switch that turns the compressor off to avoid freezing the evaporator. 

It could also be that evaporator is partially blocked which wouldn’t be helping. 

I’m no AC expert though. 

Cheers 

Bennie

[lmdew]

Thanks.

[lmdew]

If I turn off the AC when I feel the cooling going down and leave it off for 5 minutes or so and turn it back on all is good.

I pulled the Fan and Evap Cover to take a look at it.  You can see much, but it looks like new.  I'm going to talk to the AC Shop and see what they think.  

Put it back together if they don't have a solution.  I don't want to throw parts at it.  Boy I miss the 90 fans you could pull with a few screws.  Clip together plastic everything, on the 2002 and later, I'm sure.

[lmdew]

Shop said blockage somewhere.  i need those CO Junk yards!

[el_freddo]

5 hours ago, lmdew said:

Shop said blockage somewhere.  i need those CO Junk yards!

In the AC pipes/evaporator or the air ducting? 

If it’s blocked then why does the return line ice up - to me a blockage should make it shut down due to an over pressure or because it’s too cold at the evaporator. 

I hope you get this one sorted, there’s some good learning here!

[azdave]

Not sure if this helps but the only time I've had trouble with my 2003 WRX A/C system was when I temporarily wired the compressor control to remain engaged full-time instead of cycling on and off as it is supposed to do, based upon temps and/or pressures. My compressor would lock up and then start working again, over and over on my drive home from work. I deduced that the evaporator core was probably getting so cold that the return line to the pump still contained some liquid refrigerant that didn't boil off in the evap core and you can't compress a liquid so the compressor would lock up and then work again until more liquid made it to the pump again. After fixing the control issue, I removed the jumper that forced the pump to stay on full time and haven't had the issue since.

[nvu]

How was the state of old compressor, did it frag and sent metal down the line?  If you still have it around, try dumping out all the old oil.  If it's close to black, chances are it's been grinding away and the iron particles have oxidized.

If there's moisture and gunk in the oil, it gets extremely thicker when it starts to freeze.  It'll coat the walls of the evaporator and not transfer heat from the cabin.  The refrigerant stays liquid until it reaches the outside line in the engine bay, then it can finally flash off and that's why frost builds up.