I have a 1996 blazer Ls 4:3 .. we charged up the compressor and put a can of sealer in it, ran it for a good hour and it lasted about 2 weeks. The freon leaked out.. So we charged it again, this time with a bigger can of sealer. It didn't want to take the charge. So I drove it and it blows around 80 when idle with the temperature outside being 90.. When cruising, no change.. It only drops when giving it a lot of gas, going around 50 mph. Then it will drop to around 60 but the pressure from the vents isn't very strong.. what could be the issue

 

Well first off, stop using the sealer and fix the AC the right way, that will fix the problem of it not blowing cold. as for it not blowing very strong, have you checked all your other vents, like the floor vents, defrosters ect to make sure that your blend door is actually switching it over to the correct vents.

 

How do you recommend fixing the ac the "right way".. Its blowing out the correct vents just not very strong

 

I am going to say that if the pressure drops from the vents when you floor it, it is because you are losing vacuum and the system is defaulting to floor/defrost. Not positive this is the case, but it's my best guess. As for the the rest, the leak probably caused the system to lose oil and the compressor is now shot. The "right way" would be to evacuate the system, replace the compressor, receiver dryer, orifice tube, and all O-rings, evacuate the system again and recharge with the correct amount of r134 and compressor oil. Check and make sure the condensor mounted in front of the radiator is not punctured.

 

The pressure actually increases when I floor it.. and the air conditioner does get cold, its just it goes from 60 to 80 when idling..

 

I cant really think of why it would not blow that strong (it not blowing cold has been figured out, the higher RPMs spins the compressor faster)

does it blow strong when the heat is on, or is it the same problem?

 

Mine wont blow strong either....I am almost positive however that the mode selection dial, or whatever its called, is leaking air, I can hear a hiss when the engine is on and hvac is both off and on.

if your saying pressure increases when you floor it, as rich stated, thats because the compressor is spinning faster, best case scenario is the clutch is shot and slipping, worst case is the compressor itself is shot. If it was me, Id start be replacing the drier and orifice tube, and all the o-ring you encounter, make sure you get a/c rated o-rings, the assortment in the 'help' section at the parts store will NOT work.

if your still having temperature issues replace the clutch or if you can afford to, replace the entire compressor.

good luck and report back!

 

The Temperature blend door on these trucks is electronic, IIRC, as is the blower potentiometer. The only thing controlled by vacuum is the zone blend door. I believe there are 6 brightly colored vacuum lines coming out of the back of the zone switch and they connect to a vacuum hub behind the glove box. There is only one vacuum line that feeds manifold vacuum to this hub, and it routes to the drivers side of the dash, just above the center console, where it elbows to another hard line which runs to the engine compartment (a few T's along the way I believe) If you are losing vacuum at any of these spots, you will not pull enough negative pressure to distribute and actuate the blend doors, causing the system to default to defrost/floor zone.

As for the vents not flowing a lot of air with the OP, the only other thing I can guess at right now is a bad blower resistor or relay that doesn't operate properly until extra voltage is applied from the alternator spinning faster.

 

Well, the front vents do blow.. they just don't blow very hard.. On my way back from work, it was night.. Around 70 degrees outside. My ac blew so cold that I had to turn it off.. Its just during the day it doesn't want to cool right , and will blow air that's barely cold when idle

 

MAJOR ^5 to Blown262!! Ive been lookin high and low for this diagram.....and zone selection is the term I was lookin for! lol Thank you