AC compressor repair or replace?

[dosmastr]

Hi guys,

I watched the ETCG video on the AC system and have a couple questions.

I understand Eric’s warning about the ac system, how its best left to a qualified mechanic.
My car is 20 years old, worth about 1500 dollars and closing in on 200k and thus undeserving of a real mechanics touch (and cost!).

That being said wifie is nagging to fix my AC (it would make it easier to get her to ride in the MUCH more fuel efficient vehicle… so I’m willing to try it)

Option 1: repair compressor?

The shaft on the compressor has FAR too much play in it. probably 1.5 inches side to side (3/4 inch from middle) I see alot of listings for new AC comp bearings…. chances those are all I could need?

Option 2: R/R some crap

I can grab a used AC compressor on ebay for 70 bucks, Throw in a new dryer and O rings for another 50.

Then add r134a (7 bucks a can) and AC comp oil (10)

160 bucks just about…

Questions I have here are regarding the oil which remains in the system. I have access to an air compressor, assuming the system is discharged (i dont know, but with the compressor shot like this what are the chances it still has anything in there?) do I hook the lines up to the compressor and try to blow out all the old oil etc from them to start fresh?
I imagine I would want to drain the replacement compressor and replace the oil in there with new.

If the system is somehow still charged, is it even possible to perform this repair? (would mean venting the system right? and venting = unlawful

last question, is the best way to do this to wait for a very low humidity day? seems like no matter what some moisture is going to get into the system.

Thanks much.

car is a Civic lx 6th gen

Topic

[sam priem]

the best way to do it is to have a pro recover the system before you replace the compressor (incase its still charged) and then have a pro recharge the system after you replace the compressor. a pro will put a vacuum on the system to remove moisture and anything else in the system, then they will recharge it to the specific pressure, with oil, and a leak dye. it may cost a little more but its the best way to do it. most shops will do the quick recover/charge for pretty cheap.

[Its me]

I would not recommend repairing the compressor. For all that you will have to do, it is better to just replace.

Also, Do you know the condition of the system… When compressors go they often spread flakes of metal throughout the system. All of this metal has to be cleaned out with special cleaner using a special tool which uses compressed air to push it through the condenser and all the lines.

To do the Air conditioning properly you must follow the following steps.

Discharge the system in accordance with the laws of the land.

Remove the Compressor and inspect the lines for signs of destruction… The orifice tube is a very good indicator of the systems health although not all systems use an orifice tube.

If contaminated, the cleaner needs to be flushed through the system.. Oftentimes I remove lines if I have access to them and blow them out separately.

When I have any chance to replace an O ring, I do it. Ensure the O rings are coated with the proper system oil. I use a lot of PAG46…

The new compressor will need the proper amount of oil added to it if it is dry. Measure the proper type of oil you system takes… This information is very easy to find.. most take 5-12 ounces of oil. Put about 80% of the oil into the compressor directly and cycle it through by hand to ensure it gets in the compressor.

You can find your systems capacities of refrigerant and oil here—
http://www.techchoiceparts.com/refrigerant-and-oil-capacities

Replace the receiver dryer… This is good cheap insurance. Best place to buy inexpensive dryers is online… Some cost as little as $15 US.

Replace the schrader valves while it is open… cheap insurance here as well, many times leaks come from old schrader valves… Also, absolutely use a plastic cap on the system…

Assuming all the lines are now cleaned out reassemble the system. Add the remaining oil directly into the Receiver/Dryer.

Once the system is all re-assembled, then put it under vacuum. You can buy an inexpensive venturi system that works on compressed air that can pull vacuum but I don’t recommend it. HF sells a nice Vacuum pump for around $100 that does an excellent job on this.

Pull vacuum on the low side of the system system with your gauges until you have 30 inches of mercury. Do this for 5 minutes or so and then shut off the pump and turn off hose going to the low side. Wait about 15 minutes. Ensure your vacuum is still on 30 inches of mercury… If it lowers even one iota you have a leak and need to find it… Do not proceed until the system holds vacuum pressure like a rock… By the way, 30 inches of mercury is physically impossible on this earth but your gauge should read there.. the best you can do on Earth is around 29.something… Most gauges aren’t that accurate, the part that is important is that there is no vacuum leakage…

After you have confirmed that it holds vacuum, put the system under vacuum again for an hour… This will boil off all the moisture.. the physics lesson here is that moisture under vacuum lowers the boiling point to room temperature.. if you listen closely you actually may hear the moisture boiling away.

After this is complete, Then add the refrigerant… Your make and model will have an actual amount.. for example a Ford focus is 26 ounces. Oftentimes the cans are sold in 12 ounce cans so you know when you have 24.. You can get more specific by reading the weight of the can if you have a small scale…

Turn the engine on and turn the A/C on high..Set your idle where the manufacture recommends. Most cars this is around 1000-1400 rpms… At around 25 psi the clutch will kick in. This is when you will start to notice cooling… Add until the proper amount of refrigerant is added. For temperatures between 70-95 the reading should be 35 to 50 psi respectively. The high side should be somewhere around 2.2 to 2.5 X the ambient air temperature. So on a 70 degree day your low should read around 35 and the high should read 155 to 175. Different types of A/C units can be different, but these are ballpark figures. If you add the proper amount of refrigerant, your pressures should be there… There are also tables online to be more specific about pressures at ambient air temperatures.

Replace the caps and enjoy your new A/C and go and get some loving from the little lady….

If you have any other questions, feel free to shoot me a PM.

Cheers

Karl

[dosmastr]

I love you guys.

so in a nut shell, cheapest safest (assuming the pro will cost less than the 100 dollar vacuum) way to do is:

1Have everything blown out,
2fix the system
R/R:
schrader valves
compressor
dryer
any/all O-rings

3 add the oil (where you specified)

4 and have a pro purge moisture and charge with refrigerant.

Well its certainly more than I thought it would be (just Replace compressor and charge it!) So I cant do it before I leave for vaca (24 hours!) but its still a project I think i’ll undertake.

but long run, .. well lets put it like this:

My civic does 34mpg on the worst day of its life (i ran late alot that week….and was driving angry too) and has been as high as 40 (replaced mani-Cat and oxygen sensor, best tank ever!) but typically does 36ish… wifes car, 94 prizm has a great little motor, but the 3 speed auto takes what would be equal to my civic (i know because i owned a MT prizm w same motor) and drops it to averaging 25… interestingly enough the prizm likes the warm weather so much that the losses due to running the AC are offset, and mpg is ruffly the same in fall and spring with no heat or AC as the summer with AC on half everywhere she goes… if I can get mine to do say 34, and we take THAT car everywhere, especially if gas goes up, i know i’ll come out ahead before the car dies heh.

Guys thank you so much seriously.

[Author]

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