More AC problems I have not run into before.

[WarWagon]

Must be hot out here hitting 117 this weekend...

Can't get the suburban to cool down as much as it should even at freeway speed. 110 degrees out. Like the back of my shirt is soaked after a 1 hour drive.

Verified charge by recovering the system and it is at the 4 Lbs 134A spec. Compressor was replaced before I bought it and was a s#it job as the original accumulator is still on it. :mad2:

Dmax fan and Kennedy low temp fan clutch. Clean radiator and condenser. Rear air equipped.

Low side is high at idle and high side gauge flutters. ~60 PSIg low side. Reving engine to 1500 -2K brings down the low side with the high side going from 250 to 300 PSI. Again it is hot out here.

The high side fluttering make me think the compressor puked a reed valve. Just want to make sure the 'old' accumulator and the TXV on the rear system would not cause this issue.

 

[iamdave0887]

a blocked orifice tube would really put a damper on A/C performance. If the compressor was replaced before you bought it odds are it fail and puked a bunch of metal into the system.

If the original accumulator is still on it, odds are the orifice tube wasn't changed either. It is a PITA to get to in the GMT-400s which doesn't help any. It's up front by the condenser where the high side line leaves the condenser and heads towards the evaporator.

If it was mine i'd empty the system, remove all the stuff i could(minus the evap core as it's a PITA) and flush it all out. Replace the orifice tube, all the O-ring seals, and the accumulator. Add correct amount and type of oil and recharge.

I'd bet it'll work better after that.

 

[Acesneights1]

60 on the low would not indicate a clog. Those #'s sound like the system is just plain working it's ass off.I'd say it's overcharged but you verified the charge. If you close the windows let it idle for a good 15 mins in recirc with a thermometer in the duct what are you reading ? I assume you are using one of those variable orifice tubes ? I have heard people complain of what you describe. you may have to play with a few differnt ones. I have heard guys use ford ones in extreme heat areas. Never done it myself. Also how dusty dirty is the evaporator ? If it's full of crap it won't cool worth a crap either. Grab the big pipe on the dryer and see if it feels cold as well. Which truck is this on ? The 93 or 95 ? 93 of course was factory r12. Maybe worth trying to get your hands on some. the R12 does work better in extreme heat. Need a license to buy it but the problem is to my knowledge no one seels it in 12 oz cans anymore and a 30lb'er of that shit is crazy $$$.

 

[Acesneights1]

Also another thing you can try is while it's idling with the gauges on try running a garden hose over the condenser with cold water and see if that lowers the pressures.

 

[Acesneights1]

Just realized you said burb which means your 95 which was factory equipped r134a so disregard my comments about using r12. Try the cold water thing and possible try a differnt orifice tube. Those #s are wayy too high.

 

[Acesneights1]

Also need to bear one thing in mind, we here on the east coast don't get extreme heat like that. No a/c is going to cool great in that kind of weather. an a/c system on average can only drop the temp a certain percentage..in other owrds the hotter it is, the less cool it can make it.

 

[WarWagon]

My 1993 is doing better than the 1995...
Loaded the shotgun - New compressor, accumulator, and fixed orface tube. The variable orface tubes do not work with rear air models. Thanks to the members on here who found that out...

Best I can tell is the compressor has a bad valve from the flutter.

 

[Acesneights1]

93 will work better. PU vs Burb (93 probably has a Harrison compressor vs the Jap junk the later ones use to boot). I would still try the water trick and see what the pressures do but it is possible the pump is weak. If running cold water over the condenser makes a significant difference then it's possible your fan is not pulling enough air through it.

 

[WarWagon]

Swapped the compressor this afternoon. This Four Seasons compressor was made in Texas, U.S.A. (The old one was made in a different city in Texas.) Of course the accumulator and O tube was Communist China.

I had visions of "Big T pulling the dash" going through my mind with two big wrenches on the evaporator nut. I got lucky and although it fought all the way off it did not take the pipe with it. Some reason this nut tends to rust on 1995's. (Second 1995 I have had like that.) Orface tube screen was 2/3 plugged. I have seen way worse.

Charged it up and the low side came down to below 50 KPSI and the high side gauge flutter was gone. Definitely a bad valve killing one hole on the old compressor. Usually they leak or rattle like crazy with junk all over in the system for me.

She should work better now with 1/4 more compressor... :hihi:

 

[Burning oil]

First thing I thought of was a dirty evap (as aces said) Why can't VOV be used on a Burb w/rear air?

 

[THEFERMANATOR]

First thing I thought of was a dirty evap (as aces said) Why can't VOV be used on a Burb w/rear air?

You can only run one variable valve in an A/C system, and the 94+ BURBS already use an expansion valve for the rear air. I tried to run one in my BURB, and had horrible results with it as well(worked good at an idle, but was horrible going down the road).

 

[Burning oil]

Makes since. I forgot about the expantion valve in the rear.

 

[WarWagon]

Here we go again. Found the orface tube 1/4 plugged and flutter on the high side. Turns out the parallel flow condensers can't be flushed and will clog internally and be a source of debris to ruin the next compressor. As the sticker says 1994 on my condenser it is the original...