rlx101

So the a/c was not cooling really well this summer, a couple of times it got borderline warm at coldest setting, i have not added any freon in a couple of years or so. I went and added 1 bottle of refrigerant and it just stopped cooling all together. When i drove shortly after refilling i heard short loud hissing sound, when i hit A/C on and off i do not hear A/C kicking in like i normaly would.


Is this 100% that A/C is dead? If so, then how complex DIY replacement is? I've replaced starter myself, air filter, PCV, oxygen sensor - the easy stuff, do not know yet if i can pull off this one, im sure shops will want an arm and a leg to replace this. The a/c compressor itself is not that expensive as i was afraid it would be, only ~180-200$ new on ebay.

Any thoughts on how to approach this issue?

thank you!

hypervish

Bad idea to just go and add refrigerant. You may have overfilled by the sounds of it.

I suggest you take it to an A/C specialist who has gauges and a proper scale to evacuate and refill the system.

Air conditioning systems are not DIY friendly.

rlx101

if i did overfill it can i just release the excess ... or is it irreversible?

damn, i do have a filling tubing with the psi indicator but i could not find it, so i took one without, i figured i have not added any freon in years so 1 can would not overfill it... perhaps i was wrong. ill check the pressure and bleed it if needed.

what do you mean its not DIY friendly? I've been adding freon to my cars for ~10 years now, total may be 3-4 times, 1can at a time or so, never had issues. or did you mean a/c compressor replacement?

hypervish

It's illegal to release freon into the atmosphere.

The filling tube with psi gauge is not the proper equipment. You need double gauges for the low and high side.

By not DIY friendly I mean, it requires a lot of equipment to properly service an HVAC system. You need gauges, vacuum system, and a scale. It's a very complicated system. You shouldn't go to your shadetree mechanic for AC work.

You shouldn't need to add freon btw.

KLF

I was in a shop last Thursday for my annual inspection, the only time my cars see a professional garage. There was a Subaru in one of the bays, for a non-working AC system. The tech evacuated the system and found over 4 lbs of refrigerant, almost 3 times as much as there should have been. The owner was just cramming more cans of the stuff in when it wasn't getting cold enough. It ended up ruining the compressor.

Moral of the story: take it to some place that has the proper equipment to diagnose what's really going on. They really are not a DIY system, I kinda wish they would stop selling those cans of stuff in all the stores.

rlx101

ok problem solved, it looks like i indeed overfilled the system.

I measured the pressure on the low end and it was in the red part of the scale so i bled it down into the "full" area, now measuring at ~37-40psi after ~15min of running. Now the compressor kicks in and stays on after i turn the A/C on. The air is cool. It looks like what i heard (loud hissing sound) was some sort of escape valve for idiots like me. Ok, this was a good lesson that ill remember. Never fill without measuring pressure before/during and after!!!

But now im back to my original question, how do i make it blow cooler air? The whole point of this exercise was to produce better cooling efficiency. On the second car i have the A/C blows cooler air and it seems to get their a bit faster.

Any other "serviceable" parts of the A/C system that might be responsible for this?

rlx101

well the problem was as i said i could not find my filling line with the pressure monitor, so i used a regular line without one. Needless to say - It turns out it does not take much to overfill the system!

I was under the impression that the system wont take more freon than needed, it would just stop feeling, well it turns out it can take in more than it needs!

So the moral of the story - monitor pressure carefully before, during and after filling process!

I would not discourage people from careful DIY, just get a gauge and measure pressure, thats all.