Orfice tube on dual air Suburban

[Burning oil]

Where is it located? Normally in the trucks w/o front/rear a/c its in the condenser, but I have heard they are in the line close to firewall on Subs with front/rear air. Anyone know for sure?

Im wanting to replace it with a vov type.

 

[THEFERMANATOR]

Where is it located? Normally in the trucks w/o front/rear a/c its in the condenser, but I have heard they are in the line close to firewall on Subs with front/rear air. Anyone know for sure?

Im wanting to replace it with a vov type.

It's located in the Y that is atatched to the passenger side inner fenderwell, but don't waste your time as your A/C will SUCK afterwards if you put one in. I tried this and it made teh A/C work good at an idle, but it blew only mediocre at speed as the variable orifice will not function properly with the rear expansion valve, and they even tell you to not run them in a dual system with a rear expansion valve. I ended up putting an electric fan on my condenser to make teh A/C work good at an idle.

 

[Burning oil]

Thanks for the heads up. Thats all I need to hear then. If you did'int like the results then I won't waste the time repeting the same thing.
Whats wierd though is the guy at the a/c shop said it would work better at idle and the same as before at speed and that the evap valve and vov would compliment each other.
My a/c guy has been in the business over 35 years and is very knowlegable.
My old 94 truck with single cab air and vov would freeze you out of there in July. It was so nice!

 

[THEFERMANATOR]

They work great in a single app, or even with a rear orifice. Ading the electric fan to the condenser made more of a differrence than teh VOV did anyways, plus now it is COLD going down the road.

 

[Burning oil]

I was going to add a fan also. Hooked to "run" power so there is no delay in a/c cooling at idle or in traffic on hot days.
Since the engine oil cooler went away with the Isuzu swap (Isuzu is a water to oil cooler in the block) that gives me a perfect spot to add the fan. On the 454 gassers you could get a factory pusher fan its a bolt in deal. I ran two of them on a Cummins conversion.

 

[Cumminsfever]

There is a "severe duty" orifice tube available that we use in all our conversions. Any good a/c shop should know what I'm talking about. It is a variable orifice tube for low rpm/extremely hot climate situations. Expensive, but is the best I found.
works in the vans w/rear air. Never tried in a suburban tho, so I can't vouch for that.

 

[Burning oil]

I just went with what I had. Picking up aux cooling fan today. It does not seem to blow as cold as before. Pressure on gauges never got to the readings I normally see. How many ounces or 134 does the dual air burb take? According to AZ its 63oz so thats what I put in. The high side only got to 170 and low stayed up around 70. Ya'll think I need more 134?

 

[THEFERMANATOR]

What compressor are you using? SOunds to me from your pressure readings that it's not moving the volume needed for a dual air unit. Either you have an orifice that is ruptured and bypassing, or the expansion valve for the rear is hung open. With the high side being low, and the low side being high is a dead indicator of this. And the charge is right around 4 pounds, so 63 ounces is fine.

 

[WarWagon]

The VOV is simply not compatible with the rear expansion valve setup. It also does not fit in the dual system from other members posts.

I ran a relay off the compressor clutch to run a aux electric fan. This helps when the engine is cold and fan clutch isn't on. Condenser heat in the airflow gets adsorbed in the radiator, fan clutch stays off, condenser then overheats and AC doesn't cool well. The electric fan helped the AC some when the engine was cold as it moved air when the fan clutch was off. A better mechanical dmax fan and low temp clutch also helps only after engine warm up. Although the HD clutches work better the LD clutches because they always move more air even when off - as far as AC goes.

The expansion valves are famous to stick open and 'wipe' the compressor. They also have contact issues and flow more refrigerant than required see article below. You should always run the rear fan at Med with the AC on. Never have it off! The expansion valve also has a filter that can plug.

http://www.thetruckstop.us/forum/sh...fo-Yes-it-has-a-Thermal-Expansion-Valve-(TXV)

You may see ice building on on the rear lines if the valve is stuck open - while it is wiping the oil out in the compressor. Oil diluted with liquid freon... If not slugging the compressor to death by trying to compress liquid.

Sigh!
You remind me of what I have to rip out next and replace on my 1995 before it gets really hot out here.

 

[Big T]

The VOV is simply not compatible with the rear expansion valve setup. It also does not fit in the dual system from other members posts.

I ran a relay off the compressor clutch to run a aux electric fan. This helps when the engine is cold and fan clutch isn't on. Condenser heat in the airflow gets adsorbed in the radiator, fan clutch stays off, condenser then overheats and AC doesn't cool well. The electric fan helped the AC some when the engine was cold as it moved air when the fan clutch was off. A better mechanical dmax fan and low temp clutch also helps only after engine warm up. Although the HD clutches work better the LD clutches because they always move more air even when off - as far as AC goes.

The expansion valves are famous to stick open and 'wipe' the compressor. They also have contact issues and flow more refrigerant than required see article below. You should always run the rear fan at Med with the AC on. Never have it off! The expansion valve also has a filter that can plug.

http://www.thetruckstop.us/forum/sh...fo-Yes-it-has-a-Thermal-Expansion-Valve-(TXV)

You may see ice building on on the rear lines if the valve is stuck open - while it is wiping the oil out in the compressor. Oil diluted with liquid freon... If not slugging the compressor to death by trying to compress liquid.

Sigh!
You remind me of what I have to rip out next and replace on my 1995 before it gets really hot out here.

X2. I bought the VOV for my '99 Suburban and it will not fit.

 

[Burning oil]

What compressor are you using? SOunds to me from your pressure readings that it's not moving the volume needed for a dual air unit. Either you have an orifice that is ruptured and bypassing, or the expansion valve for the rear is hung open. With the high side being low, and the low side being high is a dead indicator of this. And the charge is right around 4 pounds, so 63 ounces is fine.

Its a Sanden 508. A/C guy said I could pinch off one of the suction side hoses at a time to isolate front and rear systems. Do ya'll think that sounds like a good idea? Should the gauges then read correctly assuming one side actually has a problem like an expantion valve?

The VOV is simply not compatible with the rear expansion valve setup. It also does not fit in the dual system from other members posts.

I ran a relay off the compressor clutch to run a aux electric fan. This helps when the engine is cold and fan clutch isn't on. Condenser heat in the airflow gets adsorbed in the radiator, fan clutch stays off, condenser then overheats and AC doesn't cool well. The electric fan helped the AC some when the engine was cold as it moved air when the fan clutch was off. A better mechanical dmax fan and low temp clutch also helps only after engine warm up. Although the HD clutches work better the LD clutches because they always move more air even when off - as far as AC goes.

The expansion valves are famous to stick open and 'wipe' the compressor. They also have contact issues and flow more refrigerant than required see article below. You should always run the rear fan at Med with the AC on. Never have it off! The expansion valve also has a filter that can plug.

http://www.thetruckstop.us/forum/sh...fo-Yes-it-has-a-Thermal-Expansion-Valve-(TXV)

You may see ice building on on the rear lines if the valve is stuck open - while it is wiping the oil out in the compressor. Oil diluted with liquid freon... If not slugging the compressor to death by trying to compress liquid.

Sigh!
You remind me of what I have to rip out next and replace on my 1995 before it gets really hot out here.

Thank you I'll read the link next. And, I know what you mean it was fairly hot here today, enough to get alittle sun burned.

 

[THEFERMANATOR]

Its a Sanden 508. A/C guy said I could pinch off one of the suction side hoses at a time to isolate front and rear systems. Do ya'll think that sounds like a good idea? Should the gauges then read correctly assuming one side actually has a problem like an expantion valve?

The 508 is a bit small for a dual application. It is meant for a medium sized single unit as many say it struggles with a large single unit. I know I'm running an SD7H15 which is almost double the displacement of your 508. And this is just the replacement unit for the GM compressor used from about 96-02 in the trucks and BURBS. If your rear expansion valve is working, then most likely you will need to look into a larger displacement compressor. I personally like the older variable displacement units they used to put on alot of cars. I know my JEEP CHEROKEE uses a 710 variable displacement in it which puts out a good bit more than even the 508 can.

 

[Burning oil]

Im going to play with it tomorrow.

 

[WarWagon]

Check for flutter on the high side needle. You may want to dismiss it, but, this could indicate a bad reed valve in the compressor. I have on on the shelf with this exact failure out of the 95.

 

[Burning oil]

Did'int get a chance to hook up the gauges today, just drove it around its cooling good, but its only 78-80* today.

Did get the aux cooling fan installed and wired up

Here is the part # if any one needs one GM# 15717423 or A/C Delco # 15-8686

 

[Burning oil]

Could a mod delete the three pictures of the blue truck. I loaded them at the same time, but unclicked them so they would not appear in this post. I can not edit them??

 

[WarWagon]

Most 6.5's I have do not have room for the aux fan as the oil cooler is in the way. The other side usually has a large trans cooler. Aka look in the grille before you buy one...

 

[Burning oil]

Could a mod delete the three pictures of the blue truck. I loaded them at the same time, but unclicked them so they would not appear in this post. I can not edit them??

Thanks Jeff.

Most 6.5's I have do not have room for the aux fan as the oil cooler is in the way. The other side usually has a large trans cooler. Aka look in the grille before you buy one...

In post #5 I said my oil cooler went away, but yes the fan will definatly NOT fit if you have both coolers still. Its actually made for the trans cooler/pass side.

 

[countryroads]

my burb ac problems

It's located in the Y that is atatched to the passenger side inner fenderwell, but don't waste your time as your A/C will SUCK afterwards if you put one in. I tried this and it made teh A/C work good at an idle, but it blew only mediocre at speed as the variable orifice will not function properly with the rear expansion valve, and they even tell you to not run them in a dual system with a rear expansion valve. I ended up putting an electric fan on my condenser to make teh A/C work good at an idle.

Been following this thread. I have a complete AC rebuild in a 96 6.5L diesel suburban. Mechanic is stumped (He is reputable), and I'm $1000 down the hole so far with the wife still without the rig that has air. Not good for the marriage either =) of course, it was my idea to buy the beast so we could tow.

History
2 years ago - on the day we were to take a camping trip with the kids, the compressor grenaded in the driveway w/ a 33' trailer attached to it, grenaded bad enough we had to shut off engine as clutch was seized. Wife said Rear AC stopped working earlier that day. Broke and had to replace compressor without hooking up any hoses to the new one and taped up the old high/low side lines.

1 year ago - friend of my parents wanted some work - semi reputable mechanic. New compressor. Flushed out lines. Unsure whether orifice tube was replaced. Dryer replaced. AC worked for about 3 weeks. Compressor started leaking out of back side where pressure switch is located. Mechanic probably did not flush lines enough. Front and Rear AC worked for a short time.

4 weeks ago. After the burb blew the PMD, replaced Oil pressure switch and filter housing- had sat for nearly a year while I was broke, I got up the courage to work on it again. Had a temporary intermittent temp spike. Had a bad thermostat and truck runs great now without any temporary overheating; flushed entire coolant system twice including taking off overflow tank and washing it for an hour. Took to reputable local mechanic who does not like dual AC systems, but who I trust not to screw me. Front AC worked again w/ new compressor (4 seasons reman), replaced dryer. Rear AC still did not work. Intermittent front blower fan. Replaced it without problems. Pulled orifice tube (black one), had some small metal shavings in it. Rear expansion valve was completely plugged w/ metal crap.

After 3-4 weekends of working on the beast;
- Replaced dryer again, flushed out front/rear lines w/ flush kit, took it all apart, bought new TXV from dealership for rear air (cut small hole in rear airbox), replaced entire condenser, put in a new orifice tube from Napa for suburbans w/ dual air - PN # 407308 - white/beige color), made sure the new condenser did not have an orifice tube installed. No leaks in system and held vacuum fine. Put a filter on the suction side of the system where it connects to compressor. Rear TXV valve also has factory filter. Only thing not replaced is the evaporator and that looks like suicide to me. Evaporator was flushed out from top to bottom and blown out with air with no blockages.

Mechanic says gauges look great, around 56 oz in system without any pressure spikes. Rear ac blows 55 degrees. Front AC is not working. line from y-pipe to front evaporator is cold. Top line from evaporator to acculmulator(dryer) is not cold. Mechanic is stumped. We've done this twice now and the bills keep adding up.

My concerns: It seems like the compressor is not strong enough to run both systems; or the brand new TXV is stuck open not allowing enough pressure to circulate through the front evaporator and into the dryer. Rear TXV uses factory clip to attach to tube in back. Stumped, running out of patience and money and feels like a dead end.

Orifice tube is also a bit of a concern; napa might have the wrong part # ? Orifice tube I pulled out originally was black, replacement was white.

Any help you could provide would be appreciated.

Thanks

Brock

 

[dangerousdave]

Leroy (BurningOil) is on Vacation right now and may not be able to respond 'til Oct. 1.
FYI