Hi. First time on this site. I have a 96 4dr Blazer LS. Has 92000 on it. I have a problem with the A/C. I havn't used the air for a couple of years. Now I am recharging it. First the clutch on the compressor would not engauge. I pumped in enough out of one of those DIY cans with the gauge. The clutch now turns on, and off in less than 10 seconds. I don't really understand that ambiant temp thing.. Is it what the temp is outside while I am doing a recharge?? That is kind of what I followed. Now with that hose still on the LOW valve it will go up to 55 psi when running. When it gets to the 55 it shuts off, and goes below 25 psi. I guess my question is.. How much of this juice can I squirt in while the truck is running and not hurt the system?? I shut off the truck for a couple of hrs, and tried it again. I put the A/C on Max, and full on. It just blows hot air. Another site said to add more, because there probably isn't enough in the whole system. The can has 18 onces in it. I have about 3/4 of the can in it. Should I pump some more in the system?? Thanks..

 

The system takes a certain amount of r134a, you can find it on one of the labels under the hood. It should be in the range of 1-1.5 lbs. The proper way to do it is use a recovery machine and take out everything in the system, then you know its empty, and can add the exact amount. Otherwise its guess work.

You should be getting some cool air with 55 on the low side. I bet you have a blend door stuck. Or a vacuum leak. Do all the vents switch correctly? Such as between defrost, floor and such?

I'm certified in A/C. But have very little experience. From what I've seen, that's my guess.

 

When you say you let it sit for a couple hours and tried again and got only hot air...was the A/C clutch cycling at all? It really is tough to know how much r134a to add, if the system isn't empty.

 

About all I can tell you on that is that I tried the air a couple of years ago, and it blew hot. As far as it is now. With that gauge on it. It gets real close to the red. Stops, and turns off wnd drops down into the white. I pumped more into the line qnd brought the bottom stopping point up higher. What a I was asking is if I cam pump some more into it to keep the needle in the green??

 

I did check. I can put the control between top and bottom and both work. I would like to know if these aftermarket gauges on the do it yourself recharge are true to there mark? For those with good air that have used one of these Arctic Freeze recharge kits. Is the needle suspose to stay in the green after cycling up??

 

It should stay in the proper pressure range for the ambient temperature while the compressor is engaged. The low side pressure will obviously rise once the compressor clutch disengages. BTW, don't listen to jwalker...

 

Yea DO NOT do what he/she said. If you just push the schrader valve down you'll first probably bend the seat and it wont ever seal then secondly it will create a low pressure behind the exiting refrigerant (which freezes at ambient so it would burn you if it touched you) and draw in air and therefore moisture which will ruin the condescent material in the accumulator/drier. The PROPER way is to evacuate the system as mentioned with the right recovery machine and holding a vacuum on the system with the machine to try and boil out any moisture, then putting the right amount of refrigerant in according to the underhood label and replacing the amount of oil that came out. r134a is pretty finicky about having the right amount of refrigerant in, being overcharged or undercharged will cause the system not to operate to it's full capability. Also, you're supposed to have a license to handle any refrigerant more so to know how to safely dispose of the chemical and to not cross-contaminate a system if it uses r12 or a propane type and to not be like all the people that would just dump it into our ozone which r134a does effect and causes green house gasses. Sorry bout the rant just don't want someone giving false information because they think it's right to do

 

Doesnt our sytems have a high and low pressure cutout switch to protect compressor? With correct charge I believe the clutch should stay engaged while blower on high and a/c set to a/c not max a/c cause with max a/c on it draws in air that has already been cooled and not fresh air that needs cooling like on a/c setting. I charge my dads venture and it took the whole can. Cant remember can size but it was a larger can. So either the system is over charged and cutting out on high switch or low and not enough refrigerate. Westgate is right with the whole vacuum thing. It gets out non condensibles light moisture out of the system.

 

All cycling a/c systems have low and high pressure switches, that's what interrupts the signal to the magnetic clutch.

 

On that can is a White area. Green, and Red. It says to stay out of the Red. After pumping in enough to get the compressor to engage it cycles up to just under the red. Then cycles back down and into the White area. I did another couple of pumps on the can, and it went up to the same spot on the Red, but didn't go down into the White that far. What I am asking is should the needle stay in the green all of the time through the whole cycle??