Evacuating AC system

[Chris Stewart]

I'll be changing the compressor & dryer on my '92 soon.
Any recommends as to how long to evacuate a Bravada AC system to be sure to remove any moisture?

[old_master]

Make sure you flush the condenser, the evaporator and all of the lines after you remove the old compressor, accumulator and fixed orifice tube, and before you install any new parts. Flush kits are available at most auto parts stores for around $35.USD Replace the fixed orifice tube, they're about $3. USD. It has a small filter built into it. Evacuation of the system at 29.4", (2 atmospheres, the maximum that can be obtained by any evacuator), for a minimum of one hour. Less than one hour...don't bother doing it at all. Most compressor manufacturers and re-manufacturers will not warranty the compressor unless you follow this procedure. Some even require you to replace the condenser.

[Chris Stewart]

Thanks OM! The auto parts store I trade at won't warranty without a new dry/accumilator but I can see why.
I still have a pint and a half flush left over from the 134a change over but it really smells bad....I guess I can connect a hose to catch the stuff.
I read that denatured alcohol was a good flush, what's you opinion?

[old_master]

To be quite honest Chris, I've never looked at the label to see what chemical it is. It may not tell what it actually is, because it's probably something very simple. It could very well be denatured alcohol. Rest assured, they'll have some $25 word that you can't pronounce for it though. With the expense involved in A/C repairs, I think I would use an A/C flush solvent just to be on the safe side. It may also have an additive to help neutralize acid and corrosion too. Hope this helps.

[ericn1300]

Originally Posted by Chris Stewart

Thanks OM! The auto parts store I trade at won't warranty without a new dry/accumilator but I can see why.
I still have a pint and a half flush left over from the 134a change over but it really smells bad....I guess I can connect a hose to catch the stuff.
I read that denatured alcohol was a good flush, what's you opinion?

alcohol is a good solvent and a good drying agent too. it's used to remove water from the fuel system, should do the same in the ac. just be sure to add the right amount of oil after using it because it strips out the oil as well as the water. alcohol is an interesting molocule, it's stickey on both ends. one end sticks to oil and the other to water, serving a dual purpose.

[Chris Stewart]

Thank you both, I'll use the flush since it does have the antiacid properties...but whew!!! It sure does smell bad.