Question on AC repair cost

[Joe Rampino]

According to the repair shop I need both a new condenser, and a new dryer. Condenser is $215 + $98 labor, and the dryer is $110 + $62 labor. Do both of these items go at the time? Something doesn't sound right because they diagnosed the problem through a leak test. They pressurized the system, then used uv light to detect the leaks. After they charged the system, the system blew cold air for about a week so I agree the system is leaking. My concern is that they want to charge me for a condenser and a dryer, when maybe the problem is in a hose or a fitting. I guess I should have taken a look when they were poking around with the uv light, but of course, customers are not allowed in the work area. Any feedback would be most appreciated.

 

[Chase Straw]

The dryer is usually recommended to be replaced any time you open the a/c system. If you know any hippies you could borrow their black light and see where the fluorescent stuff is coming from.

 

[Dennis Adams]

Yes they should replace the dryer each time the system is opened up, this is to make sure no humidity or moisture has found it's way into the system. A dry system is a cold system. Make sure they pull a good deep vacuum after replacing the condenser (at least 20 min) If the system holds a vacuum without loss of pressure its solid and not leaking. A lot of shops just want to rush and fill the system with freon and get you out the door.



Best



Dennis

 

[EddieS'04]

I have been able to get away without a new dryer when I had to open a new system. But I will pull a vacuum for more than 1hr. At no less than 28 to 29"hg, to boil off all moisture. If you cant pull that much vacuum. Just pull vacuum longer.

With the age of yours though, go for the new dryer and orfice. Make sure they flush the system real good. I say a new orfice because after the flush there may be some crud that will plug the old one.They must have found the leakin the condensor. They are thin aluminum tubing nowdays.

I have seen more condensors on late model cars fail than hoses. Except the o-rings. It wouldnt hurt to have all o-rings changed also, on the hose connections.

 

[Gavin Allan]

28 to 29" hg won't cut it. Make 'em pull and hold at least a 400 micron vacuum before they weigh in the correct charge.

 

[EddieS'04]

Gavin, hvac gauges measure in "hg. 30"hg being perfect vacuum. Cant be acheived, outside of special labs or outer space.. The best pump I have used only pulled 29. If you pull at least 25"hg all you have to do is Let the pump run for a longer period of time. Before you block it in for the hold test. It will pull all the moisture out. Just takes longer. Maybe one of our certified hvac techs will chime in.

You dont have to weigh 134A freon, If you know how to read your gauges along with ambient temp and evaporator discharge temp. Used my charts for many a year. Always got it right.

 

[scott degroot]

Dennis,4/6/2010 18:14 MT



Yes they should replace the dryer each time the system is opened up, this is to make sure no humidity or moisture has found it's way into the system. A dry system is a cold system. Make sure they pull a good deep vacuum after replacing the condenser (at least 20 min) If the system holds a vacuum without loss of pressure its solid and not leaking. A lot of shops just want to rush and fill the system with freon and get you out the door.



Best



Dennis

The only time it is necessary to replace the dryer is when it may have contamination in it from something like the compressor coming apart or if it's plugged. Like Eddie said just pull a good deep vacuum on the system and any moisture that is in there will be gone.



Just because a system holds vacuum for a given amount of time does not mean it is leak free. There are some parts of the ac system that get up over 250 psi and pulling a vacuum on it will not reveal a leak. Also to me it seems as if the Ford FS10 compressors are prone to front seal leakage under vacuum but not at any other time.

EddieS'04,4/6/2010 22:05 MT



You dont have to weigh 134A freon, If you know how to read your gauges along with ambient temp and evaporator discharge temp. Used my charts for many a year. Always got it right.

This used to be true back in the day. Now with vehicles using variable displacement compressors, smaller components and tons of electronics proper charge is more critical than it has ever been

 

[Richard L]

Most AC techs will recommend replacing the dryer whenever the system has been opened due to a leak because the system will draw in the moisture from the air and that causes problems with ice forming in the system.



Vaccuum will suck out any floating moisture from the system, however the dryer contains bags of desicant that trap and hold any excess moisture that gets into the system. If these desicant bags are not replaced, they may already have the trapped the maximum amount of moisture they can hold, and now your dryer is not doing anymore drying... and you may have an early failure of the AC unit. That's why it is often if not always recommended that you replace the dryer when you are fixing a leaky AC. If the AC unit has been leaking for any length of time, the desicant may be saturated with about all the moisture it can hold, and there is really no way to know or test the moisture content in the dryer.



I call them desicant bags because some older dryers could be opened and new desicant bags inserted and the dryer reassemble would be as good as new. However, most newer dryer units are not serviceable and must be replaced.



...Rich

 

[Gavin Allan]

Eddie, your thinking the old technology. Modern HVAC standards routinely specify minimum of 400 microns to be held before recharging. If a pump cannot reach at least 500 microns, it is unfit to be used for evacuating hvac systems.



Here's some basic info: