A/C broke...re-visited!

[Steve Waddington]

Its been almost two years< and I had posted a thread about getting my smog done on my '03 Tahoe LT, when the a/c quit!
Since then, thanks to all the help here, I replaced the likely culprits in the smog chain, put a few miles on it, and it passed smog just fine! So thanks for that!

Now...I still haven't fixed my a/c...and here's what I said at the time:
"...while waiting in line for over an hour with truck running and a/c on...all of a sudden there was a loud whine from under the hood! (almost like the sound of a horn with a very weak battery)
The smog guy said... “ turn off your a/c”. I did and the noise went away. Turned the a/c on again... and bad noise returned! Shit!"

Still makes that terrible noise if I turn on the a/c. No noise if the a/c is off. And the ac blows warm. Before the incident, the a/c worked beautifully, front and rear.

So...Just like I did when fixing the smog issues...I guess I'm just going to replace whatever might be wrong... the entire compressor...and I think there are a couple of other things to replace too..orofice tube, dryer, tensioner pulley, belt?
But I read where I have to purge the system first? Can I just take it to an a/c shop and tell them I'm gonna replace everything and have them purge my system...and after I install all the stuff...charge it back up? Will they even do that? Is there anything else I need to do?

And anyone have any ideas of what parts to get? There are so many listed online...and the prices vary by hundreds! I don't want cheap crap...but I don't want to overpay either! And I do have rear a/c. Does that make a difference in parts?

Thanks.

 

[Scottydoggs]

clutch on the compressor, or the compressor its self took a dump on ya.

 

[rockola1971]

You can have a shop purge your system then you are free to replace everything (compressor, orifice tube, all orings in system, drier and wouldnt hurt to flush out system either) but if you dont get it put back together air tight the shop that has to vac it down and charge it is going to either tell you it isnt sealed right (vac will tell if system is sealed or not) and give you an estimate to redo your oring work or just do it and charge you for it. I recommend having a friend that knows what they are doing help you out on your first rebuild if you choose to go that way.

That squealing noise is either the front compressor bushing/bearing failed or the compressor clutch slipping on pressure plate and is worn out. Either yields a new compressor assembly needed.

If you choose to do the rebuild yourself then I/we can walk you through the job as its being done. Its simple enough and no special tools needed to disassemble/reassemble the sytem. The compressor is tedious to remove and reinstall.

Orifice tube is in hardline forward (toward front bumper) of the brass nut. You have to remove fitting with green arrow on it to get to orifice tube. Do this when system has been evacuated of refrigerant.

 

[Steve Waddington]

Man, I'm seeing lots of different makes and parts numbers for the compressor! I DO know I need WITH rear a/c. And I'm thinking I should just get the complete kit with the accumulator/dryer, orifice tube, o-rings and oil.
Does anyone have any recommendations on which brand? And how do I look up the original parts numbers, so that I'm sure of getting the right parts?

 

[swathdiver]

Man, I'm seeing lots of different makes and parts numbers for the compressor! I DO know I need WITH rear a/c. And I'm thinking I should just get the complete kit with the accumulator/dryer, orifice tube, o-rings and oil.
Does anyone have any recommendations on which brand? And how do I look up the original parts numbers, so that I'm sure of getting the right parts?

https://parts-catalog.acdelco.com/acesCat.php?

 

[Steve Waddington]

Can you tell by looking if its the proper compressor for rear air? I see a bunch advertised that do not say if they are for rear ac or not!

 

[Steve Waddington]

OK...I'm stumped. I'm having a hell of a time trying to find information. I've decided to replace the compressor, the accumulator and orifice tube, the belt and tensioner pulley...got all the parts ordered. But I can NOT find how much PAG oil to put in! Or how much 134 to
buy. Isn't there some sort of spec sheet somewhere? My Tahoe has the rear air too.

 

[rockola1971]

OK...I'm stumped. I'm having a hell of a time trying to find information. I've decided to replace the compressor, the accumulator and orifice tube, the belt and tensioner pulley...got all the parts ordered. But I can NOT find how much PAG oil to put in! Or how much 134 to
buy. Isn't there some sort of spec sheet somewhere? My Tahoe has the rear air too.

Your replacement compressor will come with PAG oil already inside it. There will be paperwork that says how much if any needs to be added. It will be around 2-4oz if additional needs to be added. The spec for how much r134a is needed for your system will be on the tag underneath the hood. The tag that shows your serpentine belt routing...look around there on that tag and any nearby. Or you can just charge the system using outdoor ambient air temp vs pressure reading of the low side. For instance at 80 deg outside your low side should read 40-50psi with a/c on max and ran for atleast 10min to get a stable reading.

 

[swathdiver]

OK...I'm stumped. I'm having a hell of a time trying to find information. I've decided to replace the compressor, the accumulator and orifice tube, the belt and tensioner pulley...got all the parts ordered. But I can NOT find how much PAG oil to put in! Or how much 134 to
buy. Isn't there some sort of spec sheet somewhere? My Tahoe has the rear air too.

Is your sticker under the hood gone?

 

[Steve Waddington]

Is your sticker under the hood gone?

The sticker is there. Can barely read it, its kinda faded, torn and wrinkled. Same with the belt diagram...but they are there! LOL! I believe it says "R-134 a, with front + rear a/c:
Suburban 1.4 kg (3.0 lbs) or Utility 1.23 kg (2.7 lbs)". But they sell the R-134a cans in OZ, not lbs...so that would be 43.2 ounces. How would I put in the exact amount?
(I'm assuming my Tahoe falls under the category of "Utility", because it's not a Suburban. Right?)

 

[rockola1971]

The sticker is there. Can barely read it, its kinda faded, torn and wrinkled. Same with the belt diagram...but they are there! LOL! I believe it says "R-134 a, with front + rear a/c:
Suburban 1.4 kg (3.0 lbs) or Utility 1.23 kg (2.7 lbs)". But they sell the R-134a cans in OZ, not lbs...so that would be 43.2 ounces. How would I put in the exact amount?
(I'm assuming my Tahoe falls under the category of "Utility", because it's not a Suburban. Right?)

Charge by weighing it in with a scale or using the pressure chart for r134a. You will need just over 3 1/2 (12oz.) cans.

 

[swathdiver]

The sticker is there. Can barely read it, its kinda faded, torn and wrinkled. Same with the belt diagram...but they are there! LOL! I believe it says "R-134 a, with front + rear a/c:
Suburban 1.4 kg (3.0 lbs) or Utility 1.23 kg (2.7 lbs)". But they sell the R-134a cans in OZ, not lbs...so that would be 43.2 ounces. How would I put in the exact amount?
(I'm assuming my Tahoe falls under the category of "Utility", because it's not a Suburban. Right?)

Cans are 12 ounces, so put in 3 and then weigh the last can with a scale.

 

[Steve Waddington]

Cans are 12 ounces, so put in 3 and then weigh the last can with a scale.

So I'm assuming that's 12 oz of product inside the can? Then the can weighs something too. So I should use 3 cans, weigh an empty one, subtract that weight from the last can, and add that amount?

 

[swathdiver]

So I'm assuming that's 12 oz of product inside the can? Then the can weighs something too. So I should use 3 cans, weigh an empty one, subtract that weight from the last can, and add that amount?

Yep!

 

[rockola1971]

So I'm assuming that's 12 oz of product inside the can? Then the can weighs something too. So I should use 3 cans, weigh an empty one, subtract that weight from the last can, and add that amount?

No. Then youll end up with 48oz total in the system. Dump 3 whole cans of R134a 12oz (no leak seal) in a completely evacuated system and vaccumed down. Then weigh the 4th can total weight(with charge hose connected to manifold) Subtract 7.2oz mathematically from the 4th cans total weight(which will include the charge hose attached) and that will be your target weight to get to while charging the system with a scale underneath the can.

FOr example the weight of a full can with hose attached is 19oz. You will subtract 7.2oz from 19oz which equals 11.8oz. That(11.8oz) will be the target weight at which you will stop charging and there will then be a total of 43.2oz in the system. 12+12+12+7.2 =43.2oz.

 

[Steve Waddington]

OK...got all my parts and tools coming in. I have an appointment for Tuesday at a shop that will remove all the R-134 from my system so I can start! What a pain. Most shops around here don't want to do it if you're not letting them do all the work!

 

[rockola1971]

OK...got all my parts and tools coming in. I have an appointment for Tuesday at a shop that will remove all the R-134 from my system so I can start! What a pain. Most shops around here don't want to do it if you're not letting them do all the work!

Pretty typical. Because they know how much they can get out of people over a/c repair and parts markups. Especially in areas with high humidity and temps. It aint hard to keep busy working on A/C in the south...try selling them a heater though. Most people have zero inclination to understand how an a/c system works nor want to work on it. The magic of it is once you know how an a/c system works and what parts of the system are involved, you just learned how to work on a home a/c system(central air and window unit), heat pumps, refrigerator/freezer, standalone freezer, walk in cooler/freezer, dehumidifier and even industrial A/C and Chiller. They are all a/c systems. The only true differences are the way the refrigerant is metered in each type of system. They all have compressors, evaporators, condensers, some sort of refrigerant metering device and refrigerant of some type.

FYI-- A heat pump is an a/c unit with the refrigerant direction running backwards. (theres a reversing valve that causes the refrigerant to go the opposite direction of its path in an a/c operation). Other than that reversing valve a heat pump is a plain old centrail air/air conditioner.

 

[dnt1010]

It is a costly proposition in time and dollars to get setup to properly do AC service. Anything past a simple recharge for the typical shade tree mechanic might be best handled by AC specialty shop. I have several thousand dollars worth of tools that can only be utilized for AC servcie, that would be a terrible waste for a oneoff type repair...... If you are like me and have older vehicles and rental properties it is worth the effort though. Even after all these yaers I am still fascinated by how refrigerants works, latent heat thermodynamic physics still fascinates me. It is like MAGIC! LOL

 

[rockola1971]

It is a costly proposition in time and dollars to get setup to properly do AC service. Anything past a simple recharge for the typical shade tree mechanic might be best handled by AC specialty shop. I have several thousand dollars worth of tools that can only be utilized for AC servcie, that would be a terrible waste for a oneoff type repair...... If you are like me and have older vehicles and rental properties it is worth the effort though. Even after all these yaers I am still fascinated by how refrigerants works, latent heat thermodynamic physics still fascinates me. It is like MAGIC! LOL

The gauge set and vac pump are fairly cheap enough. Its the recovery unit that costs but a DIY can just drop buy a shop and pay them to do an evacuation. Everything else as long as done correctly is easy enough and cheap enough....without having to pay for parts markup at a shop which would pay for the gauge set, vac pump, valve core tool, PAG oil and refrigerant.