a/c dryer

[savitbound]

when replacing ac compressor because of clutch noise,do you you have to replace the dryer?

Sal Avitabile

[Bug512]

Are you just replacing the clutch? If so, no you do not.
If you are replacing the compressor (with clutch assembly), it is a good idea.

Only when opening the refrigeration system. Example, repairing a leak or replacing a component that entails evacuating the refrigerant, repair, pulling a vacuum and recharging.

I have replaced components without replacing the filter / dryer.

In large commercial systems (and automotive) it is very important to pull a good vacuum to rid any moisture.

Here is a good article on removing non condensables form a refrigeration system.
Click here

[TXiceman]

If it is just the clutch, just replace it and leave the compressor alone. If the compressor has not failed, keep the system open as short of a time as possible. Do make sure that the mechanic, pulls the system into a deep vacuum and holds it there to remove the non-condensible air and moisture from the system. Even if the drier is replaced, it still needs to have the system pulled into a vacuum.

Been working on large industrial refrigeration systems since 1970 and the same thing applied to them that applied to automotive systems.

Ken

[edgray]

Sal may not have the option to replace only the clutch. It seems there is a special tool requirted to R&R the clutch and also adjustment of the "air gap" is critical. Therefore "most" mech. want to just swap out the entire compressor/clutch assy, especially if THEY are not paying for the parts. I understand that is not "fair" to the paying customer, but unfortunately that seems to be the norm these days. In other words, why spend the time to REPAIR something, when you can do the "easier" thing and just change out perfectly good parts. Sorry to be so pessimistic, but that is what happens all too often, IMO. Ed

[dieselclacker]

Unless the compressor has exploded or locked up, it is not necessary to replace the receiver dryer. The dryer catches all the debris and can become plugged, causing a stoppage or slowing of the refrigerant and oil. If it were mine, and the pressures were normal and system still cooling, I would not have the dryer replaced.

Ed, sometimes you have to weigh the cost of shop labor versus cost of part and replacement. Starter motors alternators waterpumps etc, are all rebuildable, but cost prohibitive when compared to factory rebuilt units. Sad but true. May not be true in the above clutch replacement, however if special tools are not available in the shop.....

Dieselclacker

[Bug512]

In my past life I was a mechanic and if the clutch was bad that was the only part I replaced. I was fortunate to have (and still do) all the tools needed to perform this repair. It was much easier do that then opening up the system.

Parts changers are plenty, mechanics are hard to find.

[TXiceman]

Quote:

Originally Posted by Bug512 Parts changers are plenty, mechanics are hard to find.

And you hit the nail directly on the head......Very few real mechanics or techs around these days.

Ken

[DriVer]

The dryer was changed on my system however Larry at the service center had determined that it was defective and needed to be replaced. I have not see an AC tech that spends as much time charging and evacuating a system to fine tune the performance however since the last time I was in for AC service the system has been working fine ever since.

From what I was told, it is normal to see bubbles in the dryer window on the Workhorse when I thought all along that you weren't supposed to see any.

[oemtech]

A couple of comments...

Be real careful with replacement receiver/dryer's as there are a lot of stuff made in China where the desiccant breaks down and gets into the system. This can take out your compressor.

It's amazing what is considered normal by OEMs that just a few years was unacceptable.

[TXiceman]

The liquid line filter drier should have ZERO bubbles when operated steady state with the A/C fan on high and the engine at a high idle....around 1200 RPM. If you are getting bubbles under these conditions, it is under charged.

Ken

[DriVer]

Quote:

Originally Posted by TXiceman The liquid line filter drier should have ZERO bubbles when operated steady state with the A/C fan on high and the engine at a high idle....around 1200 RPM. If you are getting bubbles under these conditions, it is under charged.

Ken, I'm seeing bubbles at about 650 RPM or engine idle. I was told that this is normal. Thanks for pointing out under which conditions bubbles must not be observed.