AC issues

[Joe1]

I had the AC on my 05 Forester recharged by an independent shop early last summer as it was blowing hot and cold air intermittently. It worked fine until late September when it started to operate a bit flaky again.

I recently used the AC for the first time this year and it is blowing hot air only. I'm going to have it checked out again, but before doing so, I'd like to get opinions on what may be wrong. I find it a bit strange that the charge didn't last one summer and suspect that there may be bigger issues lurking. The vehicle has over 150k miles and I don't want to put too much into it for any repairs that may start to surface.

 

[Hokiefyd]

Most shops will advise a leak test if the system needs to be charged for an unknown reason. It sounds like you have a leak in the system and refrigerant is escaping. If the system is tight, you'll not have to "top it off" like this.

 

[Donald]

The shop should have recovered the R134A, pulled a vacuum for 30 minutes and verified it was holding. Then refill with the proper number of pounds of R134A. Did they do that?

It could be as simple as an o-ring needs replacement or a corroded condenser or compressor.

Do not use any leak sealer. It makes it difficult to recover the R134A if leak sealer is mixed in.

The shop can also add some leak detector during the fill.

 

[zzyzzx]

Just charge it again. It's not worth fixing unless it leaks out faster than that. You need to learn how to charge it yourself. It's really easy (easier than an oil change).

 

[Gokhan]

Don't charge a leaking system. Not to mention that it's illegal.

Leak tests are fairly simple. They use ion detectors and can be done in about ten minutes. All leaks must be fixed before the system can be recharged. Leaks can happen at the hoses (even through the old rubber walls), fittings, compressor, etc.

Once you fix the leak, have the shop evacuate the system for up to half hour or so. Chances are that the drier will have to be replaced before the evacuation. It can then be refilled and you will be set for many years of problem-free A/C.

Also, just the right amount of refrigerant must be in the system. Too much refrigerant will result in hot air because the pressure will be too high, raising the temperature of the refrigerant. Too little refrigerant will result in hot air as well because there won't be enough refrigerant flow to remove the heat. There is no way of knowing the amount of refrigerant in the system if you do it yourself without the necessary gauges. That's why A/C should only be serviced by qualified and certified shops, not by DIYers.

 

[AKhan87]

Originally Posted By: zzyzzx
Just charge it again. It's not worth fixing unless it leaks out faster than that. You need to learn how to charge it yourself. It's really easy (easier than an oil change).


Oh please do give links on a DIY as I would love to learn, even though all 5 of the cars I maintain have original factory fill and blow COLD air, just in case a leak develops or just for learning purposes.

It's weird how 2.5 years ago I never even cared about when to change my oil, until the head gasket on my beloved civic with 280k went bad and the idiot mechanic suggests a replacement engine instead of fixing the head gasket(sentimental attachment to the vehicle). Being without a car for 7 months...I started do ALL my car repairs myself and actually really enjoy it, it is so satisfying to me. Almost as satisfying as when I used to destroy my Calculus & Organic Chemistry exams with little to no studying at all.

 

[zzyzzx]

Originally Posted By: 01_celica_gt
Oh please do give links on a DIY as I would love to learn


Youtube, and Interdynamics website. Is Google broken?

 

[Chris142]

it can leak from any.place but being a subaru look for oily hoses.

 

[EA82]

It amezes me how some mechanics and even HVAC guys tell the customers that it only needs to be charged, they don't even bother to search for leaks.
A lot of customers are under the impression that charging an AC unit with refrigerant is routine maintenance. Numerous times I've read on craigslist where the seller states "AC works great, just needs recharging".

 

[Gokhan]

Originally Posted By: laserred96gt
It amezes me how some mechanics and even HVAC guys tell the customers that it only needs to be charged, they don't even bother to search for leaks.
A lot of customers are under the impression that charging an AC unit with refrigerant is routine maintenance. Numerous times I've read on craigslist where the seller states "AC works great, just needs recharging".

Yup, exactly. If A/C needs recharging, it simply means it's definitely broken and it needs to be repaired. Once it's repaired, it needs to be evacuated, drier replaced, and then charged.

Don't expect an A/C job to cost less than $300 - $400. It can easily go anywhere up to $1000 or more. Many parts may need to be replaced and there is a lot of labor involved -- sometimes taking the technician all day long or more than a full day.

The alternative is to drive with the windows down.

 

[1 FMF]

Originally Posted By: Gokhan
If A/C needs recharging, it simply means it's definitely broken and it needs to be repaired.


that's a very black and white way of looking at it.
refrigerant will seep out of all refrigeration systems over time, after 5+ years topping off a car AC system with 3-5 ounces when the system contains about 24 ounces is not a big deal and having to do so does not mean the system is broken.
"topping off a leaking system" is by no means illegal, certainly not for a non-licensed person working on his or her own car. Legality comes in to play when a licensed person purposely vents a refrigeration system to atmosphere prior to working on it instead of evacuating and recovering the refrigerant.


you do not want to use any type of "leak sealant" because it will clog the AC condenser and cause all sorts of other costly repairs. a common leakae point is the o-ring on the valves in the high and low pressure service ports, when you undo their plastic cap covers if you hear a little pffft that's evidence it's leaking. or you can fill the port with water and look for bubbles- just be sure to blow it out and dry it before connecting a hose. many times you can slow or stop a leak there by using a valve tool and oturn the valve a 1/2 to one turn to remove it then retighten. most every car comes from the factory with leak dye in the refrigerant, so you can use a blacklight and search for evidence of leakage along every hose and fitting. other common leak points are where hoses go from hard line to flex at that crimp point, if thats the case then you need a new hose which then would involve a full ac service