AC Compressor replacement questions

[Stevebsy]

I need to replace the AC compressor because it seized up last Tuesday.

I read that the drier should be replaced at the same time. Is this really necessary? The AC was working fine until the screetching sound of belt trying spin the locked compressor followed by no AC.

I have the compressor already..just debating whether I need to drop more $$ on a dryer too. I believe the system is still sealed because it will engage the clutch when I hit the AC button (and make a slight grinding noise)

This is on my CR-V if it makes a difference. It's waaay too hot in this place to be without AC!

[Beav]

Here's the scoop - the rule of thumb is to replace the drier anytime the system has been opened. Many OEMs are beginning to abandon the practice though, probably to save themselves money during the warranty period. I have done a number of system repairs over the past several years without replacing the drier, usually without any ill effect. Occasionally (maybe 1 out of 30?) you'll run into an issue where moisture remains in the drier and causes a performance issue.

However I do have some negative info to pass along. When a compressor siezes there will invariably be an amount of metal from the compressor blown into the system. The first place this debris will collect is in the condensor. With smaller cars and smaller systems the condensor is also smaller, In order to make it work effectively its tubes are smaller in order to accomodate more rows. These smaller tubes tend to clog a lot more easily than older, larger condensors. Sometimes the clog will occur at the entrance to the condensor, rendering it useless. Other times you may lose a number of rows, causing poor performance. In either case there will be residual debris that will begin to find its way into your new compressor, and that isn't good either. There are inline filters and screens available to place in the line between the evaporator and compressor (the inlet side of the pump) to catch this debris - I'd recommend using one. Also there is a/c flush available to clean the system, as best possible, before replaceing the compressor. Also you'll want to remove the expansion valve or orifice tube (whichever device your car employs) and clean it out. After flushing you'll need to re-introduce an amount of oil into the system itself, not just into the compressor. Find out how much to introduce, it varies between models. Remember, R134 is very susceptible to under and overcharging and too much oil will displace the room required for refrigerant.

When replacing a siezed compressor, most cars built in the past 4-5 years generally require replacement of the compressor, drier, condensor orifice tube and flushing. Can you say, "Owwww, take it out! It hurts!!"? It ain't easy being 'green'.

[kuoh]

It really depends on how long you have the system open and whether any metal bits got pumped into the system. It will absorb moisture from the air when exposed and retain any metal shavings shed by the compressor. I got an aftermarket drier from the auto parts store for about $40-$50. You may also want to flush the condenser and replace the idler pulley bearing just to be on the safe side.

KuoH

[Beav]

^^ Just remember the condensor comes before the drier. The condensor is more likely to be the main 'filter' for debris. The 200lb.+ pressure of the high side will push sharp little pieces of metal right through the drier filter bag and allow whatever made it through the condensor to lodge in the TXV or orifice tube.

[kuoh]

Morning Beav.

I've had some success reverse flushing a condenser on a 5.7L Chevy using a garden hose and water. Not the best of ideas, but we had no access to shop air and were under time constraints. Still it worked, though the reman compressor has now developed some sort of leak after several months of good use.

KuoH

[Beav]

Ya, moisture is a good oxidizer, especially in an environment where dissimilar metals are present. How did you remove the water? Inquiring minds want to know.

[kuoh]

Well, we used an air pump from one of those inflatable beds and also let it sit a couple of hours, then drove it to a shop the next morning to vacuum out the system. We were in a rush because it belonged to a family member with 3 kids who needed to make an immediate 14 hour trip in the summer heat. It was just a last minute stop gap measure, so we were fully prepared to have it come back and haunt us again.

KuoH

[Stevebsy]

I found a drier for $22, so I bought it and changed it out with the compressor yesterday.

It's working now...so I'll keep my fingers crossed!

Thanks for the help.

[Ron Mummert]

Beav, since A/C is on the table, I just wondered if any particular make of autos seem to have bullet proof systems. A friend had an '87 Buick LeSabre with over 300K that never had so much as a freon charge. My '93 Nissan 240SX with 240k still freezes my fingers off - never a repair. Even the SVX with R12 at 138k is still pumpin' the cool stuff. Who seems to have the most trouble-free systems?

Ron.

[Beav]

I can't vouch for the best but I can tell you the ones that have a lot of problems - Chrysler LH and Minivan (since the early shoebox models) evaporators, anything that uses Fridgidaire R5 compressors, late 60's, 70's & 80s GM evaporators and 90's Ford compressors (affectionately known as 'black death' - open a system and the oil was black.) Other than these most all makes have equal chances of survival.