How to waste hours on an AC for no reason

[ponkotsu]

So last fall I changed out the intake and valve cover gaskets. Truck ran great afterward. Took it out for a test drive and heard a really unusual sound. Sounded kind of like a backfire followed by a whooshing sound. It made me curious, but didn't really know what happened until a couple days later I realized my AC didn't work. Seems I accidentally knocked off the spring clip that held on the low pressure AC hose. That odd sound I heard was the sound of all my freon being dumped into the atmosphere. Oops...

So weather is getting warm now, so time to fix it. Went to the pull and pay and got a springclip for 2 bucks. Can of freon was about $40. I have zero experience working on AC systems, but I figured it couldn't be so hard. Put in the freon according to the ambiguous instructions. No go. Compressor kept kicking on and off every couple seconds. After dumping the entire can in, I did some checking on the web. Advice was to use a manifold gage in order to see what's going on. So went to Harbor freight armed with my 20% off coupon and free screwdriver set coupon and bought their POS made in China gage set. Got home and went at it again. Still no luck.

Finally I realized the problem is that you need to measure the pressure of the system WHILE THE COMPRESSOR IS RUNNING. I was injecting freon beyond the max pressure but when the compressor kicked in, it dropped to zero. Instructions on the can of freon left out that important little tidbit.

So, off to the auto store for another can of freon. (It's a big system apparently). After dumping the contents of another small can in, I once again have arctic air. Turns out the Harbor freight gage set was utterly useless for me and I'll never need it again. Guess I'll have to bring it back.

 

[koda2000]

you should have replaced your drier/accumulator if it got exposed to the atmosphere. i find most systems take about 2.5-3 cans of R134a. i've never used a gauge set yet, and have done numerous A/C system intalls (in classic cars) and modern vehicle repairs.

now, if you want to waste an hour and a half, try diagnosing why your rear wiper motor isn't working with the rear glass open.

 

[delexploder]

We pull a vacuum on the system then we bridge the AC clutch so it cant kick on and off and then open the valve on the refrigerant in. Its a few extra steps and we do it all through the gauge set mostly just to read the vacuum and the valves to keep it all tied together and closed. This is my friend and mentors old school method and I've seen 30°f at the vents on several vehicles.

 

[1996BLKBauer]

Don't feel so bad. I replaced the fuel pump in my truck by dropping the tank, just to find out the inertia switch got unplugged.

 

[Dan Whitaker]

Since it had a leak you need to evacuate the system to make sure there is no air in it.

 

[koda2000]

Since it had a leak you need to evacuate the system to make sure there is no air in it.

it's not a bad thing to do, but it isn't absolutly necessary. there's very little volume of air in the system when open, so you're not loosing much room for refrigerant. the main reason for pulling a vacuum on the system is to check for leaks and remove any moister. i've done it both ways and it has never made a noticeable difference. if you have a vac pump at your disposal, use it.