AC Repair questions.

[OpenClose]

I sent my car in to troubleshoot a growling noise the AC was making. After about an hour, they took me into the shop to show me what was going on.

The low pressure side was too high, and the high pressure side was too low. And when the engine would rev, these would not budge. They said it was a bad compressor, which I agree, and they quoted me almost $1000 to fix it. I looked at what they quoted, and I can do it for around 1/5th that.

So I have a few questions going in. Numbered them so you can reference the numbers.

1 - Do you agree it is a bad compressor? It seems pretty obvious, since a bad compressor wouldn't be able to maintain a pressure differential.

2 - How likely is it that there is a leak elsewhere in the system, and that this caused the compressor to overwork and go out? How would I check?

3 - I notice it is recommended to change the accumulator/dryer. What is the difference between an accumulator and a dryer? I noticed two tank-looking parts. The large one is obviously the accumulator/dryer, but there is also a small one that exists between the compressor and the accumulator.

4 - Are there any products/kits you can recommend? I've been looking at Amazon, since I get free 2-day shipping. I see a lot of options, and some good kits with all the parts and gaskets. I just wasn't sure if there is a huge difference between products. Same goes for coolant brands and compressor oil brands, if there are bad ones to avoid.

 

[Eddie]

$1,000 is reasonable to have a new AC compressor installed, the system evacuated and refilled with oil & pressurized with Freon. Judging from the questions you have asked, suggests that you are low on the learning curve when it comes to AC work. Ed

 

[oldoak2000]

Originally Posted By: OpenClose
I sent my car in to troubleshoot a growling noise the AC was making. After about an hour, they took me into the shop to show me what was going on.

The low pressure side was too high, and the high pressure side was too low. And when the engine would rev, these would not budge. They said it was a bad compressor, which I agree, and they quoted me almost $1000 to fix it. I looked at what they quoted, and I can do it for around 1/5th that.

So I have a few questions going in. Numbered them so you can reference the numbers.

1 - Do you agree it is a bad compressor? It seems pretty obvious, since a bad compressor wouldn't be able to maintain a pressure differential.

2 - How likely is it that there is a leak elsewhere in the system, and that this caused the compressor to overwork and go out? How would I check?

3 - I notice it is recommended to change the accumulator/dryer. What is the difference between an accumulator and a dryer? I noticed two tank-looking parts. The large one is obviously the accumulator/dryer, but there is also a small one that exists between the compressor and the accumulator.

4 - Are there any products/kits you can recommend? I've been looking at Amazon, since I get free 2-day shipping. I see a lot of options, and some good kits with all the parts and gaskets. I just wasn't sure if there is a huge difference between products. Same goes for coolant brands and compressor oil brands, if there are bad ones to avoid.



Uhh, was the AC still cooling, but just making a growling noise?

You fail to mention whether cooling was working or not - makes a huge difference in a accurate diagnosis / course of action.

the 'flipped pressure' doesnt make any sense at all (sounds like guages hooked up backwards) or they are snowballing you and you have no clue you're being snowballed.
A 'bad compressor' doesn't at all make it possible for 'pressure to flip' !!

If you really have no clue how cooling system works and experience repairing - I suggest you get 2nd (or 3rd) opinion, and forgo trying to 'diy' ; ac system has many steps required to do 100% correct, and if you do 95% correct it will still fail again in short time; It's not like replacing a alternator or a starter;

for example, you don't 'guess' where it has leaks, you do a nitrogen leak-down test or hi-vac test (with accurate guages) - do you have all this equipment?

do you know how to purge sytem of excess oil, before re-charging with new oil (required by new compressor & accumulator) ; do you know the right oil to use?

there is more - but im done

 

[Bgallagher]

Originally Posted By: Eddie
$1,000 is reasonable to have a new AC compressor installed, the system evacuated and refilled with oil & pressurized with Freon. Judging from the questions you have asked, suggests that you are low on the learning curve when it comes to AC work. Ed


I think that unless you are an AC "expert" that everybody is low on the learning curve with AC. It isn't something that should be handled on the DIY considering environmental concerns.

 

[OpenClose]

- Yes. The cooling was working. Slow, but it worked. The compressor clutch would not cycle.

- The pressures were NOT flipped. "Too High" does not mean "High"

- The mechanic gave me the option to evacuate the freon after the check. So I had him go ahead and evacuate it. I don't have money to throw around on $150 AC gauges and probably a $200 evacuator. So after the compressor and dryer are replaced, I would send it in to get it filled/oiled/checked at a much lower cost. If not, my dad has a friend who has some of these tools.

- My car was recently in an accident. Got a dent on a quarter-panel. The repair was quoted at over $3500, so the vehicle was declared totalled. I kept the vehicle and was given the value of the vehicle back, which was about $3500 after the deduction. I paid $5000 for the vehicle. That means the car was a net cost of $1500. There is no way I am going to pay $1000 to add a bit of chilly air to a $1500 car.

Similarly, I am working a temp job, and may move soon since I'm interviewing for jobs up state. So yes, money is tight. I partially bought the car so I could learn how to do repairs myself.

So I am either doing it myself, or I am running without A/C. Simple as that. Yes I have read article, seen videos, etc.

 

[Donald]

If you insist on doing it yourself, drive it to a shop, have them purge it of old R134a. You can then replace the compressor and other needed parts and any O-rings you can find (cheap to replace with system open). Do not connect the electric to compressor. Drive to shop and have them do an AC service the system, tell them new compressor, and hand them the oil.

Of course you may not get much of a warranty doing it yourself.

R134a gets added by the lb or oz, not to a certain pressure. You need special equipment unless this is a beater.

 

[spackard]

No, he's really low on the M-HVAC learning curve.
At least get your Section 609 license.
https://www.macsw.org/imis15/MACS/Sectio...rtifcation.aspx

That only costs $20. It asks enough questions that you should get some red flags on whether or not you really want to go down that road.

It cost me about $1600 in equipment to gear up for R-12 work, and a lot of that was used equipment.

 

[Merkava_4]

1999 Buick Regal 3.8L Supercharged V6

ACDelco A/C Compressor $190.79
ACDelco Accumulator Dryer $19.29

Total: $210.58 at RockAuto prices

$1000 minus $210.58 = $789.42 Labor

I had no idea I saved that much money when I did mine. I payed a diagnostic fee; went home and changed the parts; brought the car back to the shop for refrigerant charging. I had about $350 into it total.

I might add on mine: I changed the Compressor and the Orifice Tube; not the Accumulator/Dryer. I added about 4 ounces of PAG 150 oil to the new Compressor. I also back flushed the A/C Condenser with denatured alcohol.

 

[DoubleWasp]

Bad compressor? That system needs to be flushed, badly.

*compressor
*orifice tube
*accumulator/drier
*whatever hose that contains that tank looking thing needs to be replaced


Ditch that condenser too, unless you are really confident it will be flushed out really well.

 

[mk378]

Noise from inside the compressor means that you need to replace it. Like others said, compressor coming apart inside will contaminate other parts of the system with metal debris.

This is almost certainly a V7 variable compressor system. The control valve inside the compressor can go bad and cause it to run the low side too high, or not pump at all. Replacing the whole compressor will of course resolve that.

 

[OpenClose]

OK, so here is my update. I decided to try to confirm for myself whether or not it would be worth doing the work immediately.

My dad can get an evacuator fairly cheap, and I found a gauge set for $40. Not as bad as I was thinking.

So anyway, I went ahead and refilled it. The car takes 36oz of r134a and 8oz of PAG 150. I was able to get this stuff fairly cheap, and added some UV dye we had from AC work on another car. So I'll run it like this for a while and check for leaks.

One thing I noticed is that the noise is almost completely gone, and the air now comes out at around 42F. So this will definitely hold me for a while.

(FYI, the noise was a light growling. Roughly like the sound of an aquarium bubbler. I didn't notice it until I got a quieter muffler.)

The compressor clutch doesn't cycle, so it isn't maintaining pressure somewhere. If I can't find any leaks, I'll work my way to changing that compressor and accumulator, and back flushing the evaporator.

Originally Posted By: Merkava_4


Total: $210.58 at RockAuto prices

$1000 minus $210.58 = $789.42 Labor

I had no idea I saved that much money when I did mine. I payed a diagnostic fee; went home and changed the parts; brought the car back to the shop for refrigerant charging. I had about $350 into it total.


THAT is the plan. They were charging around $400 for the compressor, $500 for labor, and the rest for the refrigerant. Seeing as kits are available for half that, and I just refilled my system for $25, yes, it feels like a rip.

I generally only send my car in for diagnostics whose tools are expensive, and tire rotations. And for the muffler. Otherwise, I do all my fluid changes including my parents and brother. Rebuilt my AC blend door servos, my mom's electronic throttle body, transmission accumulators, and do internal repair on small engines, such as our riding mowers. I haven't done much AC work, but my dad rebuilt a freezer we use in the garage, so I get info from him. I knew the function of the dryer, but wanted to ask about the differences between parts, and hear recommendations for products.

Basically, we don't spend money on labor if we can fix it ourselves.

 

[nthach]

Originally Posted By: DoubleWasp
Bad compressor? That system needs to be flushed, badly.

*compressor
*orifice tube
*accumulator/drier
*whatever hose that contains that tank looking thing needs to be replaced


Ditch that condenser too, unless you are really confident it will be flushed out really well.

In newer cars, you basically need a whole new AC system as any particulate from a failed compressor will travel and it will stay in the evap/condenser no matter how well it's flushed.

GM used constant-cycling clutch systems as well.

 

[Merkava_4]

This is a condenser back flush kit. You fill it with denatured alcohol and spray it in. It forces out all the crud from the failed compressor. You gotta have a source of compressed air though.

 

[The_Eric]

Originally Posted By: OpenClose


Originally Posted By: Merkava_4


Total: $210.58 at RockAuto prices

$1000 minus $210.58 = $789.42 Labor

I had no idea I saved that much money when I did mine. I payed a diagnostic fee; went home and changed the parts; brought the car back to the shop for refrigerant charging. I had about $350 into it total.


THAT is the plan. They were charging around $400 for the compressor, $500 for labor, and the rest for the refrigerant. Seeing as kits are available for half that, and I just refilled my system for $25, yes, it feels like a rip.



You guys need to remember that shops almost never buy from the internet. Many times the Rockauto price is in the ballpark or lower than shop cost- or least mine. You also need to remember that it's a business (not an evil empire) and needs a mark up to make money to cover parts cost, pay the utilities, insurance... all the stuff you have to pay in life and much more.

Just because you can spin a few wrenches and buy some stuff off of the internet, doesn't mean they are ripping you off.

 

[Merkava_4]

Originally Posted By: The_Eric
Just because you can spin a few wrenches and buy some stuff off of the internet, doesn't mean they are ripping you off.


Maybe we should continue spinning our own wrenches, but make a charitable donation to our favorite auto repair establishment once a month. After all, those poor guys need to eat too.

 

[SpecM]

Originally Posted By: The_Eric


You guys need to remember that shops almost never buy from the internet. Many times the Rockauto price is in the ballpark or lower than shop cost- or least mine. You also need to remember that it's a business (not an evil empire) and needs a mark up to make money to cover parts cost, pay the utilities, insurance... all the stuff you have to pay in life and much more.

Just because you can spin a few wrenches and buy some stuff off of the internet, doesn't mean they are ripping you off.


Bingo

I just looked up my cost on a new compressor/drier/orifice combo from local NAPA, it is nearly $300. Most shops will not use discount internet parts.

OP: Also, the price of repair HAS TO include a return on investment for the expensive shop equipment that you have not purchased, and they did.

You went to a retail place, you pay retail prices.

 

[The_Eric]

Originally Posted By: Merkava_4
Originally Posted By: The_Eric
Just because you can spin a few wrenches and buy some stuff off of the internet, doesn't mean they are ripping you off.


Maybe we should continue spinning our own wrenches, but make a charitable donation to our favorite auto repair establishment once a month. After all, those poor guys need to eat too.

Now there's an idea!

I take cash, check or credit card...

 

[wtd]

Back in 2006 I learned how to do AC repair by going on the internet and asking questions and reading on auto ac forums. I also bought a couple of good books.

I bought two set of gauges, one for R12 and one for 134A, a vacuum pump, a refrigerant scale,flush gun, can tap, some O-ring kits, and other small things. I also got my 609 certificate through MACS.

I also bought several 30lb bottles of R134a as well as one mostly full bottle of R12.

If I know that the compressor failed and I find debris on the OT if it has one, I will replace the entire AC system minus the evaporator which I will flush out.

To date, I have repaired about 10 vehicles, four of them my own. On my two 98 chevy trucks, I replaced all of the AC components except the evaporators. I even replaced the lines that had mufflers built in because these cannot be flushed.

One one of my 92 Cavalier's, I retained the R12 and on one I converted it to R134a because at the time, I did not have my 609 cert so I could buy R12.

So far, none of my own vehicles have required repairs again with the oldest one done almost 10 years ago. The newest one was done about 5 or 6 years ago. In AC work, it's best to do the repair correctly the first time so you don't have to do it again soon after fixing it the first time.

Wayne

 

[Merkava_4]

Originally Posted By: wtd
I also got my 609 certificate through MACS.


What is MACS ? Please fill me in. I'd like to get my 609 too.

 

[wtd]

Originally Posted By: Merkava_4
Originally Posted By: wtd
I also got my 609 certificate through MACS.


What is MACS ? Please fill me in. I'd like to get my 609 too.


Go here. This is where I got mine. You have to register on this site and then click on the link to purchase the test you have to take. It is an online test. I don't remember what score you have to get to pass but it tells you all of that.
https://www.macsw.org/imis15/MACS/Sectio...rtifcation.aspx

Wayne