AC Dryer / Evaporator...replace or try it?

[MikeM]

My 93 SHO was in an accident and the AC lines were broken open.

1. Is it true you have to replace the AC Dryer / Evaporator once the system has been opened for 24 hrs. or longer?

2. It was mentioned to me that some mechanics will attempt a procedure called boiling the dryer to evaporate the moister that has been drawn in...has anyone ever heard of this or had it performed?

Need some advice...thanks. Mike

 

[rangerj]

MikeM,

If the compressor is replaced with a new, or rebuilt, compressor the filter/dryer, or as ford calls it an accumulator/dryer, should be replaced.

When the system has been open to the air it will have moisture in the system. How much moisture will depend on the amount of humidity in the air. The way that moisture is removed is to vacuum the A/C system before it is charged with refrigerant.

A vacuum of approximately 27 to 30 inches of mercury (HG)for an hour should remove the moisture. Water will boil at room temperature at 27 to 30 inches of vacuum (HG). When water boils it turns into oxygen and hydrogen gases, which is vacuumed out of the system.

In the filter/dryer there is a filter (DAH), and a chemical desacant that absorbs moisture (dryer). Some old mechanics (like me) will heat the filter/dryer canister to get the desicant to dry, or release any moisture it may hold.

If the system is vacuumed properly, then this is not necessary. I recommend vacuuming for 45 minutes to an hour, then waiting a half hour to a full hour to see if the system holds vacuum (i.e. no leaks). If there are no leaks I vacuum for at least another 30 minutes to an hour depending on the humidity and temperature.

In cooler weather I set the shop light against the filter/dryer to "warm" it. In hot sunny weather I set the A/C parts in the sun for a while before installing them. I let the car sit in the sun while I am vacuuming the system.

Should you replace YOUR filter/dryer? If the compressor is in good shape the filter/dryer should be OK. rangerj

 

[DHMag]

ok..RANGERJ...i have a question or 2 along these lines...my compressor is locked up. i have a replacement for it (not rebuilt) that id like to install. i think the compressor locked up because of too much oil (R12 converted to R134 [ 3 cans with 3oz oil charge, not to mention the R12 oil that was already in there]). could i just clean out the system, replace the orifice tube, and install the new compressor ? i understand the accumulator has a silica in it and does not like to be open to atmosphere too long. would i hurt the accumulator by flushing it with an A/C cleaner ? also, where is the orifice tube located ?

Thanks In Advance

 

[shotimev6]

anytime the system is open, replace the dryer

 

[rangerj]

DH

The oriface is in the high pressure line before the evaporator core. The line goes in to the firewall. Most A/C folks I know recommend replacing the oriface line as a unit. Splicing in an oriface tube, in a high pressure line, has a low success rate. (leaks are common) The line from an aftermarket supplier is about $40 to $50.

The accumulator cannot be "flushed out". It accumulates all the waiste and wear products of the system, eg bits of microscopic metal, nylon, etc. It also can be purchased from the aftermarket suppliers for $75 to $100.

A flush kit is about $50. The vacuum pump and gauges can be borrowed from Auto Zone for a hefty deposit (refundable).

Vacuuming is the key to removing moisture from the system, including the dryer. Water in the A/C system will do to your compressor what a quart of water would do to your engine! Would you change engine oil without changing the filter?

When you remove the compressor let me know if it is full of oil. I'm guessing that the oil is trapped in the filter and that the compressor siezed due to a lack of oil, or due to moisture.
Please let us know what you find.

If you decide to replace the accumulator/dryer, then cut open the old one and tell us what you find inside of it!

The total amount of oil in the A/C systen should be 7.75 ounces, 8 ounces is OK, but do not exceed 8 total in the system. You can add the oil with the refrigerant cans, but the compressor should have 1.5 to 2 ounces in it to start. rangerj

 

[DHMag]

rangerj:
DH

The oriface is in the high pressure line before the evaporator core. The line goes in to the firewall. Most A/C folks I know recommend replacing the oriface line as a unit. Splicing in an oriface tube, in a high pressure line, has a low success rate. (leaks are common) The line from an aftermarket supplier is about $40 to $50.

ok, now ive been told its on the high side. other A/C techs have told me its on the low side. is the orifice tube accessible from the engine bay without much trouble of getting to it ? if you say its easier with the motor out, id have to say "ugh." i just put the motor back in from a clutch job. O'Reillys sells an orifice tube, direct replacement(orange), for like 3 dollas. can i buy this and do it ?

on another note, i dismantled the old compressor to see why it locked up. a piston locked up and trashed the swash plate. the little gizmos that ride on the swash plate that support the pistons got tossed, prolly by my 5K rev merging into traffic (thats when it happened). ill have pics some time.

 

[rangerj]

DH,

Yes, you can buy the replacement oriface. The oriface line is the small diameter line. The large line is the line the accumulator dryer is on.

The oriface is back near the firewall and is covered over with rubber tubbing that you roll back to get access to the oriface. As I said earlier, most A/C techs have told me they have few sucesses with replacing just the oriface.

The oriface line connection at the firewall is the only hard part of removing the line due to a lack of room. The "orange" oriface is the right one.

Have fun, rangerj

 

[projectSHO89]

On my 89, the orifice is located in the tube at a position below and just lightly forward of the PS reservoir, just under the rear corner of the battery.

Steve

 

[DHMag]

RANGERJ

ok, bought an orange orifice tube, but i guess i really need the line assembly. do you recall the part number from A-Z ? O'Reilly wants to sell me the line with accumulator for 120, does that sound right ?

thanks again

 

[projectSHO89]

Dale,

Wrong line.

Tell them you need the high pressure/liquid line. That one already has the O-tube installed in it at the factory.

It's about $25 at AZ or O'R #55613

Steve

<small>[ May 06, 2003, 03:12 PM: Message edited by: projectSHO89 ]</small>

 

[rangerj]

DHMAG, What made you change your mind about changing the oriface tube, as opposed to the whole line?

Steve is right the accumulator/dryer line is the suction or low pressure line. The oriface line is the high pressure liquid line.

If you are going to take the system apart you should consider replacing "O" rings and garter springs. You could give R-134a conversion a thought also, if you are still using R-12! rangerj

 

[<BUBBA>]

Hi, I plan to change over my 93 ATX from R12 to 134A. I plan to replace the orfice with the New VOV (variable orfice valve) It should make things colder 5 to 12 Degrees on average at idle. Has anyone heard about this ? It's called Smart VOV .

 

[Levand16]

just gut the a/c system that's what I did! light weight for racing boink

I know I'm gonna miss that A/C in the summer but the SHO isn't going to be a daily driver anymore...

 

[DHMag]

rangerj:
DHMAG, What made you change your mind about changing the oriface tube, as opposed to the whole line?

Steve is right the accumulator/dryer line is the suction or low pressure line. The oriface line is the high pressure liquid line.

If you are going to take the system apart you should consider replacing "O" rings and garter springs. You could give R-134a conversion a thought also, if you are still using R-12! rangerj

i removed the line today and i dont see how i can fit the orifice tube in there without cutting and splicing. or is that what you originally meant ? once i got the line removed and saw i couldnt just pop out the old orifice and pop in the new one, i put it back, and went to work. i already did the 134 conversion, and since ive been trying to figure out why the A/C doesnt wanna work, ive been thru 6 cans of 134 (6 dollas a pop). here is the problem im having: it will accept and hold freon. the compressor will cycle like it should. but while running, there is no pressure to register. when the A/C is off, i have pressure. is that my orifice tube clogged up ? a friend said thats what it was. i wont lie, but im stupid when it comes to A/C systems. mainly because i never had to work on them.

im a few days away from driving 1000 miles for vacation and with no A/C, its gonna be a long drive. the weather here in TX lately has been in the 90s with very high humidity, kinda like the summer back home in Indiana.

thanks for all of your help RangerJ

 

[rangerj]

DHMAG,

If you had the oriface line out why didn't you replace it? I cannot say for sure that the oriface line is the problem with out more test information. But if you got an opinion that the line is plugged up (a common problem) why not replace it?

rangerj

 

[projectSHO89]

i dont see how i can fit the orifice tube in there without cutting and splicing. or is that what you originally meant ?

Yep, that's how it's done. Now you know why I said to replace the whole line.

Buy your R-134 at Wal-Mart, it's only $4 or so per can. If you think you'll be doing a lot of this, you can buy the 30# cylinder at Sams' Club for around $75 or so. (Last year's prices).

Post your low and high side pressures. With the compressor clutch disengaged and the engine cold, the static system pressure should be between 60 and 90 psi on both sides, depending on the outside temp.

When the compressor clutch engages, a normal guage response would be to see the low side pressure drop and the high side rise. Once at operating condition, the low side may be between 20 and 40 psi and the high side would probably go above 200 psi. These readings are VERY general. These readings will vary greatly depending on the ambient temp and the actual state of charge of the system (and the actual condition of your system).

Steve

<small>[ May 08, 2003, 03:51 PM: Message edited by: projectSHO89 ]</small>

 

[DHMag]

rangerj:
DHMAG,

If you had the oriface line out why didn't you replace it? I cannot say for sure that the oriface line is the problem with out more test information. But if you got an opinion that the line is plugged up (a common problem) why not replace it?

rangerj

i was able to get the line loose, but unable to remove it from the vehicle. so i poured some rubbing alcohol in it, and shot a blast of air thru it. i did this several times, then reinstalled. i didnt replace because i dont have the complete line assembly (tube and hose). the next day, my friend told me that i could use a Dremel, cut the sides of the coupling, filet it open, and pull the hose off the ******. then after installing the new orifice tube, i could cut the line to fresh, slide it back over the ******, the use 2 hose clamps to tighten it down.

though, after having it off and halfass cleaning it, i do have *some* cool air now. temp gauge reads 60 degrees. its better than it was. as for pressure readings, on the low side, i can only get about 44 when system is operating, RPM doesnt matter, though fan speed does. if i turn the fan up, the temp goes up. leave it low, and it will prolly get below 60 degrees. before this, i wasnt able to get any pressure reading from the low side at all. and the last time i attempted a high side reading, i blew the gauge apart, so i dont check high side any more. and even before all that, i could get a low side reading of 60, before the compressor locked up.

i leave for Indiana tomorrow morning so i wont be able to do anything about it til later. in fact, i have another problem that popped up.....heater core went out today. ill bypass it for the time being. perhaps, when im able, ill email you the entire story about my A/C endeavor.