AC compressor replacement

I might be in a little over my head on this one. I had my AC checked out recently and they told me one of my hoses was leaking, and they think my compressor is failing. I didn't like the price tag, so I asked them to drain it, and planned to replace the compressor and hoses myself.

After looking into it, I ordered compressor, hoses, condenser, and expansion valve, because it seems like there's a decent chance that if my compressor needs to be replaced, the condenser could have some problems too.

Now there seems to be a lot of talk about correct oil levels. Some sources talk about measuring the amount of oil in your old compressor and putting that much back in with the new compressor. Other sources have said that if you have a leak, then that isn't reliable because some of your oil probably left the system, and that might be why my compressor is failing in the first place. If I was replacing the whole system, then it seems like I could just have the full system amount in there as specified, but I hadn't planned on replacing the evaporator...

So...
Should I be replacing the evaporator?
In either case, how do I figure out how much oil and where it should be added before starting the system?
If the plan is to take it to a shop to have them charge it with freon, is there an option where I just leave it dry and ask them to add oil as required?
Or whatever other advice anyone has to offer.

 

I wouldnt worry about replacing the evaporator if it's not leaking, flush it out with some A/C flush, blow it out with compressed air, put a full charge of oil in the system since your replacing all the other components, reassemble, and have it evacuated and recharged.

You need to pay attention to the amount of oil the new comperssor comes with, some come with none, some come with a few ounces, and some come with a full system charge.

Also after installing the compressor and connecting the lines turn the clutch part of the compressor a few turns to expell any oil that may have collected in the pumping cylinders and prevent damage from hydrolocking.

 

I'll tell you from experience that a shop might not want to service your A/C system unless you've also replaced the receiver drier and expansion valve along with the compressor, but it depends. Some shops don't care, others simply won't honor the work afterwards if something happens after the fact. On some vehicles the receiver drier is part of the condenser... I'm not sure if that's the case with he Tacoma or not. Also depending on where your compressor came from it may come serviced with oil or you might need to add it manually... I'd say most people add the oil to the low pressure port, cycling it by hand afterwards if possible.

 

I was a bit confused about that part. A lot of people seem to say something like "receiver/drier/condenser" so I had reached the conclusion that they were names for the same part. My compressor did come with oil, but I am now trying to figure out how much, and how much I should have total. Sounds like I should drain it, see how much is in there, and then adjust to the full system spec as suggested by Dm93.

 

Yes the reciever/drier is built into the condenser, on older vehicles they were a separate canister but on most everything now they are part of the condenser and serviced with it.
There is also a screen in the line by the expansion valve that should be replaced when servicing the valve.

 

See post 5 in this link:

 

I don't know how the Tacoma works but on some vehicles,
they require that the A/C charge be present, because the PAG oil inside spread out throughout the circuit, helps keep the compressor lubricated when it is running
whereas it risks potential damage if the system is empty, without that PAG oil circulating, but belt still turning the compressor; unless the clutch turns it off.
This is why some people, if doing this, will purposefully find a smaller serpentine belt size to bypass the compressor temporarily, and drive with that shorter belt on until the repair is complete
to avoid the situation of making the vehicle undriveable and in need of a tow.

I am curious about this because RockAuto catalog made it look like the reciever/drier is separately replaceable (it is on some vehicles) as a dessicant bag that can be slid out of the condenser by unscrewing a tube cap.
I don't know if that's actually true or not.
Some vehicles have it replaceable, while others are integrated and not removable/part of the condenser


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OP. Drain the system. Evacuate. Recover. Vacuum. Charge to required amount with R134a. Re-add any PAG oil you removed, using R134a compatible PAG oil.
With UV dye in it.
Hopefully everything is plugged in, with no torn wires, and no fault codes stored.
Run it, see if it works.
It can help to have a clean condenser. AKA water/pressure wash.
And clean cabin filter so it can breathe.
Measure the vent temperature. Laser thermometer is like $20 and lots of people have them from COVID.
Feel the metal pipes. One should be hot, and one cold.
Look at the compressor. Make sure the front pulley doesn't have obvious damage to indicate it is sheared, grenaded, etc. including torn rubber, if it's one of those designs.

Leaks can be found with yellow glasses, UV flashlight (good tool to have), to look for dye. There's UV sniffers that beep but are expensive.
It's harder to find a leaking evaporator because it's buried behind the dash.
Every car is different. Some have known problems.
For example, leaking seal at the back of a Tacoma auto transmission? Known problem.
Certain GM trucks/Chevy with poor weld leaking condensers up front? Known problem.
Never heard of A/C issues plaguing the Tacoma. Other things? Yes. A/C? No.

High pressure sensors (in general) can fail, not giving the computer the info it needs to know A/C is safe to turn on.
Air blowing hot usually means the condenser is blown.
You can also hook up manifold gauges to check the pressures.
The idea is to do as much diagnosis/small cheaper stuff as possible first, before committing to a $1k compressor, to try and be absolutely sure that's the problem.

Condenser? Up front. Like a radiator. Can re-use them, if the dessicant/reciever dryer is separate. If integrated, replace together.
If you find debris in the system from the compressor, you must do a flush, including bypassing any restrictor devices and replacing them, both to get good flow during the flush, and replacing any debris clogged components.
Evaporator; people re-use those if they're not leaking.
Hoses/lines; replace if leaky/punctured etc.
replace seals when removed if you can, and lube with PAG oil

There isn't enough information in your original post to know if that particular shop is full of shit or not.
A/C is usually left to shops because a Robinair A/C machine can cost $5k, plus refrigerant, plus a flush machine.
Cheapest I've ever seen a machine was a shop that bought one used for $1k from another shop that couldn't figure out it was "broken" because they didn't have oil in the machine vacuum pump.
Don't lean on the machine or it can interfere with the scale weighing how much R134a is being added.
Cheapest I've seen 1hr recharge is $100

I bet the EPA legally requires people be certified to work on A/C systems given the inherent hazards. Toxic gas, flammability, can be harmful to environment, disposal procedures, etc.
Yes, there are DIY tools that cost less; but still expensive.

That is tricky and I don't know the answer to that. Usually you're supposed to simply watch how much PAG oil is removed during evacuation, whether that be digitally recorded on a machine, or visibly seen on a catch bottle marked with tape, to then simply re-add what was taken out.
Too much may hydrolock the compressor.
Otherwise, new compressors are supposed to be shipped pre-filled with the required factory amount of oil, and capped with sealing plugs to keep it inside. I've heard sometimes they can be knocked out during shipment, but never dealt with that.
I have seen experienced people not care about recording PAG oil removed to re-add which tells me it probably doesn't matter THAT much
If an A/C system (on any car) is not working, I'd bet it's from a component failure, and not minute difference in PAG oil present in terms of fluid ounces

 

I would say to have the leaking hose changed out first and if the compressor continues to perform poorly afterwards get a new Denso compressor.

 

Good discussion.... I haven't had to work on my Tacoma A/C system yet but it is unfortunate that they have the receiver/drier built into the condenser.

 

on one side it could be nice to replace because you’d be getting rid of an old one that might have bug dents and a film of dirt over the years reducing efficiency and making the compressor work harder that can be difficult to clean

on the other side I’ve cleaned condensers with AC coil cleaner spray and garden water hose with spray attachment or pressure washer
And due to how the front and grill of the Tacoma is shaped I don’t think mine has let any bugs get in there to strike and bend the fins despite years and miles
Some bent fins (not a lot) is usually considered fine to use

 

The problem with this setup up is that you really should replace the receiver/dryer anytime the system is opened up. So, if you just had a leaking o-ring and fixed that, you would now need to replace a $200 or $300 condenser instead of a $30 part. Or more likely let it go, which would not be the best thing.

 

TacoTuesday1 wrote:
"Air blowing hot usually means the condenser is blown."

Negative.