Car A/c Maintenance

[groovyc]

I need some oiling up with my compressor. Whereas a little oil injection will do the job, I am told that they will only add oil if I do a full coolant change. Does anyone know if I really have to do that, or would I be able to find a place where they'll just inject a bit of oil into the system? Also, if any mechanic around Bangkok/Nonthaburi is recommended, please advise. Thanks in advance.

[Naam]

I need some oiling up with my compressor. Whereas a little oil injection will do the job...

how do you know that you need "some oiling" up? if you had lost compressor oil then the refrigerant would be zero too and you'd need a full charge of refrigerant and oil. no oil loss without refrigerant loss.

[cali4995]

The correct amount of refridgerant oil for a given system is a finite thing depending

on it's capacity. Probably why the local garage doesn't want to just "add extra" it

very well might cause problems they would then seem to be liable for. If the system

was evacuated (drawn down with a vacuum pump) the correct amounts of refridgerant

and oil could then be added without mistake. If you have leaks, you would notice wet

spots where a little bit of everything has been coming out. To answer your question,

Yes, you can just get a little can of oil and "shoot" it in there but as Naam says, you

might want a more accurate diagnosis of what the actual problem is. Good luck.

[sunny747]

i was going to post issues with AC. i was driving to bangkhen beach and on the high way i saw white cold breeze coming out of the Ac. i didn't care. while at 120km suddenly my car engine has shut off. lucky that there were no car behind , i could safely park on the left side. after that i could turn on the engine but just when i put the Ac on, i heard a crack sound the engine got shut again. later i just drove without Ac.

when i came back to bkk they said my compressor need to replace. all together they charged me 4500 baht for ching kong compressor, dryer with 3 months guarantee.

i don't know why it happened. how do i take care the AC? ............

[cali4995]

Well, I suppose the Thai service guys are quite competent because most car AC is running

nearly constantly as opposed to perhaps a seasonal thing in other countries. There is a

pressure switch on the system where if you had a leak the clutch on the compressor would

disengage to avoid damage, maybe that didn't happen? That really doesn't sound like a

bad price for repair, those parts can be expensive.

Just common sense stuff really, is the AC belt in good shape and the belt tension adequate

to avoid slippage. When you turn the unit on you should be able to hear the clutch engage,

a clacking sound, open the hood and have someone switch it on and you can watch it operate

and familiarize yourself with the noise. If it's frequently cycling on and off during normal

operation, most likely the system is low on refridgerant and needs servicing. And if the system

has leaks you need to find those, there all all manner of leak detectors from dyes you can put

in the system to sniffers which beep like a geiger counter. If you hold your had over the duct

you can get a pretty good indication if it's working properly, a thermometer stuck in there would

be more accurate and you could remember what normal operating temps where.

When the system is serviced, there is normally refridgerant oil mixed in with the freon, r-12, r-22

or whatever it's called anymore. Compressors and clutches only have so much life and when they're

running all the time, they do sometimes have to be replaced.Blah,blah,blah, volumes of useless trivia.

[sunny747]

thanks so much for the info cali4995. i really appreciate.

[cali4995]

The one other thing is the drains. There will be condensation dripping off the evaporator core

and it has to go somewhere. Normally you'll see a little puddle forming under your vehicle

if left sitting in one spot but, I think as has been covered on topics here before, they can get

clogged with mud, leaves debris, and form moldy areas which lead to unpleasant odors wafting

into the cabin of your vehicle. There, you now know everything I learned in my wayward youth.

[torrenova]

Yeah, I was worried about that discharge when I got my new vehicle here.

[groovyc]

Thanks a lot for the replies, guys.

The correct amount of refridgerant oil for a given system is a finite thing depending

on it's capacity. Probably why the local garage doesn't want to just "add extra" it

very well might cause problems they would then seem to be liable for. If the system

was evacuated (drawn down with a vacuum pump) the correct amounts of refridgerant

and oil could then be added without mistake. If you have leaks, you would notice wet

spots where a little bit of everything has been coming out. To answer your question,

Yes, you can just get a little can of oil and "shoot" it in there but as Naam says, you

might want a more accurate diagnosis of what the actual problem is. Good luck.

I did hear about the "too much oil is no good" thing before, but the fact is that I do

have a oil leak at my condensor. The a/c has been gradually losing its cool. My regular mechanic suggested oiling up a little bit, but they gave me two options at the a/c technician's:

1. Change the condensor (rebuilt?) and refrigerant for B5000+

2. Change the refrigerant for B1800 (with no guarantee as they wouldn't fix the condensor)

I still wanted to try adding in the oil first as the pressure at the low side was normal (30 psi?) presumably indicating no significant refrigerant loss...(am i wrong?).

I would like to "shoot in" the oil myself, but can't seem to find the oil at the local spares/maintenance shop. Nor do I have the equipment (oil injector).

I am also a bit skeptical about the necessity of switching condensors. Aren't condensor leaks fixable?

[cali4995]

If you have a little pin-hole in the condensor, what at first you might only

see is a smudgy, greasy, oily wet area. If you were to look even closer,

you might see bubbles coming out because it's guaranteed the freon is

leaking out as well. This little amount of refridgerant oil leakage I would

not worry about. I'd say it's a pretty sure bet you're system is low on

freon but without replacing the condensor it will just leak out again. You

can get radiators repaired, condensors with the pressures involved, might

be more trouble than it's worth. I guess you're looking at baht 5k repair,

and they might also suggest replacing the receiver/drier. You really need

a shop to do this as they are supposed to evacuate the system as well.

[sunny747]

i just installed a new compressor and dryer coz my previous one was burnt. but i'm still having the same problem. Although it gets cold, at 120km plus i notice a white cold smoke comes out from the AC. The air is cooperatively hot.

Last time when it happened, i turned the AC high and i lost my compressor.

what could be the reason?

thanks.

[cali4995]

If I needed to take a wild guess, I would say your evaporator had a leak,

and when the fan was blowing air over it in the duct, some freon was

mixing in with the outside air. This is why the system should be checked

for leaks, preferably when it has had a vacuum drawn down on it, simply

by closing all the valves and waiting 30 minutes to see if the vacuum holds.

In your previous post, you said these items were installed by the shop so

maybe they need to do some checks so you don't have a repeat incident.

[Naam]

I did hear about the "too much oil is no good" thing before, but the fact is that I do

have a oil leak at my condensor. The a/c has been gradually losing its cool.

if your a/c still cools (even slightly) you do not have an oil leak. there is no such thing like an oil leak and still any amount of refrigerant in the system.

[cali4995]

The light oil is carried throughout the system suspended in the refrigerant. There

is no separate reservoir as you have in an engine crankcase. If for example, a

small stone was somehow able to get kicked-up from the road and made a tiny

hole in the condensor, everything would eventually leak out. But since the r-134

freon is colorless, odorless you won't see it. A/C repair almost has to be done by

a shop anymore, not just the special tools but avoiding venting to the atmosphere.