Adding R-134a my Blazer...

I have a 98 Blazer LT, 4.3 v6, 4x4, 4 door.
 
Now that I need to use the air conditioning, it doesn't seem to be as cold as it used to be. It's 66 degrees (it's going to be 75 degrees today) outside this morning with a RH of  52%, the temperature of the cold air coming out of the vents is 62 degrees (with all windows closed). The truck is probably hotter since it sits on my driveway in the sun .
 
I purchased a charge kit that has a pressure gauge attached. I followed the directions on the can and I have some questions. I set the blower to max, the temp setting to max, opened the windows (so the compressor remains on), and I let the truck idle for a bit.
 
The compressor clicks off and on. Is that suppose to happen or is it suppose to stay on steady with everything set to max?
 
Also, the pressure gauge attached to the can reads on the high (45 to 55psi yellow warning) side when the compressor clicks off but when the compressor clicks on, it reads to the middle of the fill area on the gauge. Which do I follow? Should the pressure remain steady?
 
I've owed the truck since new and never had the A/C serviced. I've recently had a full tune-up done including rotor, cap, plugs, fuel filter, & wires. Other things done: intake manifold gasket replaced, oil cooler lines replaced, oil pressure switch replaced (due to an eratic oil pressure gauge).  Next, I'm going to replace the oxygen sensors to see if I can get better miles. This truck is costing me some cash but she's my baby.
 
BTW, you guys are the best. I'm mostly a lurker but I've been through hundreds and hundreds of post and I've learned so much about my truck. Thank you!

Same thing was happening to me last summer. As far as I know the compressor only does that when it is low on freon fluid. I read the gauage as the compressor was on, that is what you are supposed to read it by. So while the compressor is on add the amount of fluid needed till the gauage reads full. I did that to my truck and it worked perfect afterwords. Just make sure to follow the instructions that came with the kit. Also if you got the cheap kit the gauage might just be ****ty. But I know that adding the fluid while the compressor is on is what you are supposed to do.

-Lenny

Best way to add refridgerant is to actually jump the clutch at the A/C compressor.  Supply power and ground to the compressor clutch to engage it and then start the truck.  This will maintain constant operation of the compressor while you are filling it.

You will use the pressure with the clutch engaged to determine your fill level.

You guys are the BEST!!!!!
 
I followed both of your directions and guess what??? I addded R-134a to the system as the compressor kicked on. Then before you know it, it remained on and I was able to complete the fill up. Now, instead of 62 I get 40 degrees at the vents. The compreesor no longer cycles off and on... just nice and steady.
 
Thanks again for your help.
 
Now on to the oxygen sensors. Easy to do??

no idea never done them on this truck, I recall seeing one or two of them while under the truck so they didnt look to hard to get to. good luck, once the blazer starts running right you'll really enjoy it.

-Lenny

Lenny, based on all the work I've had done so far, she runs great. Nice and smooth and the engine feels strong. I just need to get back my MPG.
 
I've already been under the truck and I ordered (and received) the three sensors from getgmparts.com. I'm just wondering how difficult it is to work under the truck in such confined areas, being as I don't have a lift.
 
Thanks again for your help.

That is a pretty good price on the sensors.  However, you don't need to replace the rear-most sensor unless there is a code stating that something is amiss with it.  The post-cat sensor has nothing to do with the fuel supply duties of the engine.  Only the upstream sensors are involved with engine managment.

swartlkk, thanks for the info. I figured that since I'm under there gettin 'er done I might as well do all three. You have to understand my luck. I will get under there, yell a few choise words, replace only the upstream sensors, then a few miles later... I get a code on the post-cat sensor. That's my life in a nutshell. So, I've learned, it's all or none in certain instances.
 
Wish me luck!

Well, I keep all of my old sensors that I replace based on a scan of their output due to lack of activity.  For the post cat sensor, all that it is there for is to monitor the catalyst.  Therefore it doesn't need anywhere near the activity of the upstream sensors.  If my post-cat sensor were to go bad, I still have my old upstream sensors to try out. 

But do what ya have to do.  Just tryin' to help ya save $50.

"If my post-cat sensor were to go bad, I still have my old upstream sensors to try out."
 
I see what you're saying. I wish I had thought of that before I ordered them.  
 
"But do what ya have to do.  Just tryin' to help ya save $50."
 
Thanks, I appreciate your input.
 
BTW, I understand that ACDELCO and DELPHI are one in the same. Is that true?

Hmm...  Not sure on the AC Delco and Delphi...  I do believe that NTK (NGK) is supposedly the manufacturer of the sensors for AC Delco / GM, but I cannot prove it.

But anyway, just stay away from Bosch and Borg Warner as those are the two that I have used in my Bravada with absolutely HORRIBLE results as found through my scans.

My 2000 blazer compressor is doing the same thing, cutting on for a few seconds and then off.  I tried adding R-134a while the compressor was on, but it never kicked in or got cold.  Can someone elaborate on how to jump the clutch and what is needed to do this?  Thanks again for any information.

Ok, I'll try to point you guys in the right direction.  For me, I find it easier to pull the A/C clutch relay and jumper pin 30 to pin 87.  This should engage the clutch.  The relay is located in the underhood fuse block for the 96+ crowd...  Not sure on the older ones.

kyle my 99 does not show the numbers you specify? can you elaborate further. I am havinf the same problem ans i appreciate your know how!
 
tonio

hmm...  Well, the relay's on my truck (OMRON 8567 - OEM # 12088567 all except for one) had a diagram on the side of it showing the schematic of the relay as well as pin numbers on the very bottom next to each pin.