97 Tahoe condenser recommendations

[FellowTraveler]

I went home during lunch and replaced the accumulator. It held vacuum for 15 minutes.... so I started the pump again to dry the system. By the time I get home it will have been under vacuum for about 4.5 hours. All I need to do is charge the system and reinstall the grill. Then I’m ready for the next thing to break!

Nice, I have a big 2 stage vacuum pump w/muffler and it draws down any system fast what I like is that you actually see the steam as it is pulled from the system.......yes it sucks but it's supposed too.

 

[n8in8or]

I have AC!



Oddly the gauge pressures are a little low for the ambient temp, but oh well. And it seems like whenever I work on AC it’s not very hot outside which never gives me a ton of confidence in the readings. I’ll throw the gauges on again when it’s actually hot out. As you can see, they aren’t the best brand, so it could possibly be the gauges or could it be the 170,000+ compressor? Regardless, by the vent temp I’m satisfied.



I started with the factory charge of 3 lbs (48 oz). And then when the gauges were reading I low tried adding about another 6-8 oz (I’m filling from 12 ounce cans) and the pressure still didn’t really rise. Rather than risk putting too much in I decided to not put any more r134 in.

 

[WarWagon]

The VOV messes with "normal" pressure readings. You just overcharged the system and the overcharge raises the level in the accumulator. I suggest recharging to the proper amount by weight. Note your low side near the freezing kick out point - do you have the blower fan on high? The high side can be lower if the fan is locked in esp. in mild weather.

 

[n8in8or]

The VOV messes with "normal" pressure readings. You just overcharged the system and the overcharge raises the level in the accumulator. I suggest recharging to the proper amount by weight. Note your low side near the freezing kick out point - do you have the blower fan on high? The high side can be lower if the fan is locked in esp. in mild weather.

Yeah the fan is on high and the recirc door is open.

 

[WarWagon]

Can't ask for more than near freezing with R134a as the switch will shut it off. Just not enough heat to raise the high side combined with the VOV efficiency improvement. Move it to AZ and watch the high side go through the roof...

 

[n8in8or]

The VOV messes with "normal" pressure readings. You just overcharged the system and the overcharge raises the level in the accumulator. I suggest recharging to the proper amount by weight. Note your low side near the freezing kick out point - do you have the blower fan on high? The high side can be lower if the fan is locked in esp. in mild weather.

Could the parallel flow condenser have added refrigerant capacity to the system?

 

[THEFERMANATOR]

Look up a 1995 gas 350 Yukon. The switch on the condenser (where you have a cap now) would force the recurc door closed with high head pressure. It could be used for an aux fan if you can get one to fit with engine and trans oil coolers. The calabration on the switch is perfect to run the aux fan. Road speed should cool the condenser and switch the fan off.

The high pressure safety is on the compressor.

Bad idea, that switch doesn't change(open) until 300+ psi and back closed at 290 iirc. GM made switches just for this as I have one in mine. They install into the high pressure plug in the compressor. Mine turns on at 280 and off at 210 for an aux fan(used in the 454 2500 subs), but they also make an on at 230 off at 180(for straight electric fan usage like a fiero or fwd car), and an on at 250 and off at 230 iirc.

 

[THEFERMANATOR]

Could the parallel flow condenser have added refrigerant capacity to the system?

No, they should actually reduce the capacity slightly. How much oil did you add back to the system? Should have added 2 ounces for the drier another 2 for the condenser, and an extra ounce for good measure.

 

[n8in8or]

No, they should actually reduce the capacity slightly. How much oil did you add back to the system? Should have added 2 ounces for the drier another 2 for the condenser, and an extra ounce for good measure.

I added about 3.2 ounces total.

 

[FellowTraveler]

I added about 3.2 ounces total.

While there are more tubes their much smaller than what you had and sometime require an inline filter on older systems that were flowing black debris w/Freon.

 

[n8in8or]

While there are more tubes their much smaller than what you had and sometime require an inline filter on older systems that were flowing black debris w/Freon.

Interesting. I was thinking more about the manifold tubes on each end of the core possibly adding volume. I guess I’ll be taking the refrigerant out, adding more oil and recharging.

 

[FellowTraveler]

Interesting. I was thinking more about the manifold tubes on each end of the core possibly adding volume. I guess I’ll be taking the refrigerant out, adding more oil and recharging.

It is hands down more efficient than what you had, I'm thinking using the larger accumulator that is for the dual HVAC could accept just a little more R134a w/o issue. I have moved away from R134a awhile back and use only Industrial EnviroSafe organic Freon substitute now which is a whole different ball game as you use much less than you would w/Freon.

 

[WarWagon]

Could the parallel flow condenser have added refrigerant capacity to the system?

If you read the VOV info link they give you a idea of how the system is charged. More or less the evaporator is flooded full with some liquid in the accumulator. Leakage reserve and you got 1/4 lb to play with in the accumulator. The above is how they determine the charge weight. Thus a larger condenser doesn't affect design charge weight.

When the system runs where things are changes as you now have liquid coming out of the condenser and boiling gas in the evaporator.

 

[Will L.]

If you read the VOV info link they give you a idea of how the system is charged. More or less the evaporator is flooded full with some liquid in the accumulator. Leakage reserve and you got 1/4 lb to play with in the accumulator. The above is how they determine the charge weight. Thus a larger condenser doesn't affect design charge weight.

When the system runs where things are changes as you now have liquid coming out of the condenser and boiling gas in the evaporator.

I knew a vov allows condensor size increases, but I wonder how bad it is if the evaporator is way oversized.

 

[n8in8or]

Ok. So I’ve been trying to gather info on what to do about adding an appropriate amount of oil. While doing that I’ve also stumbled on some weird info regarding oil to use and the refrigerant charge! Let’s see if I can lay this all out.

Everywhere I look, it says the total oil charge is 8oz. Ok. But then I see that the system should take either PAG 46 OR PAG 150! What?? I used PAG 46 because that’s what my brother found when he looked it up at work. Well apparently there was a GM Bulletin that said they wanted you to use PAG 46 for all applications except R4 and A6 rather than the original PAG 150. Since I have the H6 compressor, I’m good to use PAG 46 instead of the original PAG 150. Whew. I found the same Bulletin issued by AC Delco in a nice format with additional info.



Ok so now on to how much oil. I found a lot of conflicting info on how much to put in for components. Unfortunately I don’t have a factory manual, so I decided to go to the library to look it up. They no longer have service manuals, instead they have a subscription to Alldata. Here’s the info they have.



This seems pretty reasonable to me, so I’m going to go with these numbers. I briefly mentioned it before, but this is actually the SECOND air conditioning leak I’ve dealt with this year. The first one was a slow leak at the compressor hose connection. For that leak I replaced the accumulator. I added 3 ounces of oil at that time because that’s the info my brother found when he looked it up. So not only am I short on oil this time, but I was also apparently short on oil last time as well. Here’s some math I did and based in that I am going to add 2.0 ounces of oil to correct both errors (this gives me a little extra for fudge factor).




And then the refrigerant amount. This is dumb. I charged the system with 3.0 pounds of refrigerant last time. That was based on the sticker on the accumulator I removed the first time which looks to be factory.



Well as I was looking up oil quantities I noticed refrigerant quantities that were a lot less than that!! Alldata says 2.0 pounds and 4 Seasons says 2.25 pounds???




I guess I’ll go for the lesser amount and see how the gauges read. I can always add more later. I’m refilling from 12oz cans, so 2.25 is easy for me to do, but I will try to shoot for 2.0 and see how the gauges read. This is all so dumb. It doesn’t seem like it should be so difficult to find the info I need to service this thing correctly.

Check this info out and see if you come to the same conclusions I did.

 

[FellowTraveler]

NOTICE TO STAFF "IF THIS VIOLATES RULES PLEASE DELETE"
I use these when in doubt takes the guess work out of the equation.

https://www.ebay.com/itm/R134a-A-C-...er-Analyzer-Tester-2-pack-5030a-/121989881398

 

[n8in8or]

NOTICE TO STAFF "IF THIS VIOLATES RULES PLEASE DELETE"
I use these when in doubt takes the guess work out of the equation.

https://www.ebay.com/itm/R134a-A-C-...er-Analyzer-Tester-2-pack-5030a-/121989881398

Huh. I didn’t know such a thing existed. Thanks!!

 

[Twisted Steel Performance]

My AC guy has a conversion chart he goes by that converts R12 fill to R134... I have the correct info wrote down somewhere for my dually but at this time I don,t remember the numbers..

 

[WarWagon]

Ok. So I’ve been trying to gather info on what to do about adding an appropriate amount of oil. While doing that I’ve also stumbled on some weird info regarding oil to use and the refrigerant charge! Let’s see if I can lay this all out.

Everywhere I look, it says the total oil charge is 8oz. Ok. But then I see that the system should take either PAG 46 OR PAG 150! What?? I used PAG 46 because that’s what my brother found when he looked it up at work. Well apparently there was a GM Bulletin that said they wanted you to use PAG 46 for all applications except R4 and A6 rather than the original PAG 150. Since I have the H6 compressor, I’m good to use PAG 46 instead of the original PAG 150. Whew. I found the same Bulletin issued by AC Delco in a nice format with additional info.

View attachment 53207 View attachment 53208

Ok so now on to how much oil. I found a lot of conflicting info on how much to put in for components. Unfortunately I don’t have a factory manual, so I decided to go to the library to look it up. They no longer have service manuals, instead they have a subscription to Alldata. Here’s the info they have.

View attachment 53203

This seems pretty reasonable to me, so I’m going to go with these numbers. I briefly mentioned it before, but this is actually the SECOND air conditioning leak I’ve dealt with this year. The first one was a slow leak at the compressor hose connection. For that leak I replaced the accumulator. I added 3 ounces of oil at that time because that’s the info my brother found when he looked it up. So not only am I short on oil this time, but I was also apparently short on oil last time as well. Here’s some math I did and based in that I am going to add 2.0 ounces of oil to correct both errors (this gives me a little extra for fudge factor).

View attachment 53206


And then the refrigerant amount. This is dumb. I charged the system with 3.0 pounds of refrigerant last time. That was based on the sticker on the accumulator I removed the first time which looks to be factory.

View attachment 53205

Well as I was looking up oil quantities I noticed refrigerant quantities that were a lot less than that!! Alldata says 2.0 pounds and 4 Seasons says 2.25 pounds???

View attachment 53204 View attachment 53209


I guess I’ll go for the lesser amount and see how the gauges read. I can always add more later. I’m refilling from 12oz cans, so 2.25 is easy for me to do, but I will try to shoot for 2.0 and see how the gauges read. This is all so dumb. It doesn’t seem like it should be so difficult to find the info I need to service this thing correctly.

Check this info out and see if you come to the same conclusions I did.

So AllData is not showing SUV's: just pickups. The factory sticker for R134a at 3lbs is gospel, period.

 

[Will L.]

It has been so many years since i did a lot of a/c work, and I get into more stuff than my brain can remember so I don’t have THE answer, but...As some of our guys here are pro hvac guys, they might explain it better.

Automotive is the only place that does refrigerant and oil by only weight instead of difference in pressure high vs low, sub freeze, compressor amp draw, etc.

When a an a/c unit is done for a house for instance, there is a base charge by weight, then the gauges, amp probe, thermometer is used to get the exactly amount of refrigerant installed. For the oil, since hermetically sealed compressor is used, almost never is more oil added. But in automotive, if you drain the compressor and flush the system, you have no oil. You can then add the full amount.

Anyways, back when I was doin a/c in semis and trucks, i would charge to specified amount. Then tweak it and get as much a 5 degrees colder. More oil is safer for compressor, but less cooling. So I ran little
less oil, more r12 or r134a, and she wasmuch happier. But I also installed different spec pressure sensor to shut system down when any leak started to save the compressor.

I figured out the difference in a week, wrote it down and used it for a few years, then when I quit wrenching, chucked my notes. If a pro hvac guy could help out here, it could help your performance by explaining how much extra oil there is.