Repairing ac system

[scott2093]

do you have a vacuum pump to draw it down and check for leaks before you recharge it? Worth borrowing or buying one online imo

If you borrow a strong one, it's probably good to open up the unused connector cap a bit to not pull vacuum too fast... I borrowed my neighbor's 6cfm Robinair and it has that option....

 

[Zack8]

If you borrow a strong one, it's probably good to open up the unused connector cap a bit to not pull vacuum too fast... I borrowed my neighbor's 6cfm Robinair and it has that option....

Thank you I’ll make sure to watch that, I believe I only bought one that goes up to 3.5CFM so I don’t think it’ll pull it too fast.

 

[movietvet]

IMO, make sure you leave the vacuum pump on the system for at least an hour, and more if is feasible. Besides pulling a vacuum, moisture removal in the system is being done. Moisture turns in to a gas when in a vacuum and the pump pulls that out. The idea is to have the absolute least amount of moisture in the system, as well as holding a vacuum.

Also, the closer you are to "sea level" to more vacuum you will pull. Places like "Death Valley", where you would be below sea level, you can pull vacuum of close to 29" at sea level and even a bit higher below sea level.

 

[1998_K1500_Sub]

That is refrigerant oil. You will need to add oil back when you reseal the system. Can pour it in the accumulator, that you should also be replacing. You will have a certain amount of oil sitting in the bottom of the compressor. If you remove the compressor and dump oil out you can measure in ounces. You need to look up what the entire system holds, so you can add new accordingly.

This ^^^

When your system blew-down through that hole, it may have carried quite a bit of out oil (GM speaks to the rapid blow-down situation in their FSM in the AC section on oil balancing).

 

[1998_K1500_Sub]

Hey quick question this is one of my lines coming from the compressor to the accumulator do you know why the oil would have a orange tint too it

Good question. Refrigerant oil is clear unless it's had dye added to it, and then it's green-ish.

I'm interested to hear what others say, as I've not seen it that color.

 

[1998_K1500_Sub]

IMO, make sure you leave the vacuum pump on the system for at least an hour, and more if is feasible. Besides pulling a vacuum, moisture removal in the system is being done. Moisture turns in to a gas when in a vacuum and the pump pulls that out. The idea is to have the absolute least amount of moisture in the system, as well as holding a vacuum.

^^^ yup

And if you can close the valves and let the vehicle sit, do so. Leave it overnight. The vacuum should stay unwavering at the same value when you return the next day. If not, you've likely got a leak or you had some residual water / flush that vaporized in that time. Find and fix the issue.

And change the oil in the vacuum pump occasionally; the oil in the pump can get contaminated and, if so, the pump won't pull full vacuum. ALWAYS keep a quart bottle of pump oil handy, that way it's there when you need it.

Note that only ONE service fitting uses a Schrader valve. Take note and buy a proper replacement for the other.

(sorry for the parade of posts folks, I should have merged these three into one)

 

[Zack8]

Good question. Refrigerant oil is clear unless it's had dye added to it, and then it's green-ish.

I'm interested to hear what others say, as I've not seen it that color.

I was still kinda wondering that all I’ve seen about the amber color I got out of the lines is the system is contaminated. I was thinking maybe water got in from the hole on the condenser, but I don’t think the ac system was used very much from inspecting other parts so I’m not sure how that water would get in the lines.

 

[1998_K1500_Sub]

I’m not sure how that water would get in the lines.

A few things can happen:

- The system breathes, e.g., through barometric pressure changes as well as simple air exchange

- "Exposure to the elements"... the condenser is in front, exposed while driving to rain

- The oil is hygroscopic, meaning it has an affinity for water, so once the moisture gets into the system it may not get out

Also, remember that regular (single-end capped) PAG forms a sludge-like substance when it picks up water, so your system may have its share of oil sludge that you need to flush out.

 

[Zack8]

A few things can happen:

Hey I got a question. I just received the new compressor, condenser, drier
It says my compressor is prefilled with 8oz of Pag 46. 8oz is max oil for my system will this disperse thru the system from the compressor?

 

[1998_K1500_Sub]

Hey I got a question. I just received the new compressor, condenser, drier
It says my compressor is prefilled with 8oz of Pag 46. 8oz is max oil for my system will this disperse thru the system from the compressor?

What I would do is

- drain the oil from the compressor (the Sanden doc attached gives generic instructions for draining)

- measure the amount drained from the compressor

- assume 0.5oz will remain in the compressor after draining

- add the above two values, that's the total oil charge provided from the compressor (they're usually filled with the correct amount, but sometimes they aren't...)

- add/remove any shortfall / excess to what you've drained...

-- e.g., if the system needs 8oz and you drained 7oz (and remember there's 0.5oz remaining in the compressor), then add 0.5oz to what you've drained

-- e.g., if the system needs 8oz and you drained 9oz from the compressor, pour-off 1.5oz (remember there's 0.5oz remaining in the compressor)

- place half of the oil you now have in the accumulator (3.75oz in this example, more or less, it's not critical)

- (re)place the rest of it in the compressor

That's how I do it.

Upon initiating operation, the circulating refrigerant will carry oil from the accumulator to the compressor, which aids lubrication.

Long-term, yes, even if you didn't follow the instructions above, all oil in the compressor would (eventually) find itself dispersed throughout the system.

Use clean measuring devices. Any debris/crap introduced into the oil will circulate in the system forever.

Peruse the Sanden information attached, it's somewhat generic to all compressors and there may be instructions within that you may find interesting.