A/C Dryer unit

Always replace the dryer. I contains a bag of desiccant that absorbs moisture. Any time the system is opened for component replacement, air and therefore moisture gets into the system. The dryer can only absorb a small amount of moisture before it becomes saturated and therefore useless. You will have to evacuate (pull a vacuum) on the system before you recharge it, after the repair. That will remove the air and some moisture from the system, but it would take days of constant vacuum to force the desiccant to give up its stored moisture. Also, as the desiccant bag ages it becomes prone to rupture A new dryer will give you many more years of service than taking a chance on an old one that might rupture and contaminate the system. The new dryer will also do a better job of removing any residual moisture left in the system after evacuation, so you will not have to pull a vacum for as long. About 90 minutes sould be sufficient time.

Moisture is an A/C systems worst enemy. The dryer contains desiccant to absorb any remaining moisture after the system has been serviced and vacuumed. Unfortunately when a system fails or is left open for service the desiccant becomes saturated and is no longer any good. Also the bag gets old and can break making a big mess in the system. No, buying a used one makes no sense at all. Buy a new one and replace it immediately before connecting the vacuum pump.

You also need to replace the orifice tube while you are in there. The screen on the orifice tube collects any junk that has made its way through the system over the years.

Steve B.

Glad to see you are participating in this group again, Kevin. I seemed to note that you were not so active for a period.

Hard to believe that any one could remember me from those 12,000 or so posts a few years ago . Took me until now to get over the inundation of spam caused by regular posting to the news groups. I have matured and have better spam filters. Always glad to help.

I would not be too worried about that. It is remarkable the damage these can sustain and not leak.

???? Might make no measurable difference at all.

Dessicant to trap moisture. Moisture inhibits cooling, corrodes fittings, eats holes in the evaporator, damages compressors etc. etc etc.

None whatsoever. It will probably come to you saturated with moisture and useless. Would you put a used oil filter on your new engine? Buy a new drier and put it on as the very last thing you do before evacuating the system. The moment it is unsealed it is absorbing moisture unless installed and under vacuum. in If you have to take the car somewhere to have the evacuation and recharge done have them replace your dryer.

Don

Why would you ASSume that its the compressor? A hung open thermal expansion valve or a low freon charge will give the same symptom.

It does exactly what its name implies- dries the refrigerant/oil charge. It should be replaced every time the system is opened for more than a few minutes, ESPECIALLY on an R-134a system. It contains a dessicant that absorbs water from the refrigerant and oil and keeps it trapped in the drier where it can't harm the rest of the system. R-134a oils usually have a fairly high percentage of water straight from the manufacturer (they're hygroscopic like brake fluid is) and depend on the system drier to make the final charge drier than the oil is when you put it in.

Is there any sense at all in buying a used

That all a moot point if the poster does not have a vacuum pump and proper gauges at his disposal. Some people think you just gas up and go.

Bob