1998 4x4 vortec 6. A/C Probs

Ok, I have searched the forum for my problem and found nothing, so I am posting. I hope that I didn't overlook a posting of this same prob.
The pressure in the system is good. I added r-134a in the system with leak stopper and dye indicator. I haven't found a leak and it holds the pressure. But, I have noticed that the compressor kicks on now. At first, I guess it never kicked on because of too low of pressure.
Anyways, The compressor kicks on for about 3 seconds, then kicks off. Over and over. It will kick on for 3 seconds, kick off, and stay off for about 15 seconds. Over and over.
I'm wondering if it's a relay problem. I put my finger on the relay and it does kick on and off. You can feel the click on both instances.
I don't know how to test a relay, I actually should though being that i'm into electronics.
Anybody have this problem?
It's hot here in Phoenix and it will get to about 115 to 118.
Any help or suggestions will be greatly appreciated!
I will even post back if problem is solved.
Thanks.

More than likely, you need to add more 134a. Sometimes one can isn't enough. Your compressor cycle is too short. It shouldn't cycle every three seconds. Twenty seconds is more the norm.

Make sure you add refrigerant with engine on and AC on full blast.

Do you have the type of 134a with the pressure gauge and refrigerant all-in-one?

I bought a can of "R-134a Complete Service Kit"
Contains: In-Line Recharge Hose with pressure guage, 134a Refrigerant, Stop Leak, Oil Charge, Cool Down, O-Ring Conditioner & Leak Finder Dye.
The pressure is good or should I say at the Full range. I put this stuff in and at first noticed that it was very low in pressure. Also at first noticing the low pressure, I also noticed that the compressor wasn't kicking on. With this one can, not even fully dispensed, like about half way done with the can, the pressure climbed up and it got to a certain pressure and thats when I noticed the compressor kicked on.
Let me ask this...
When i'm adding the stuff in and the blazer is running, The a/c is running on full power, I do notice this on the pressure guage, The needle goes up to "good pressure", Then when the compressor kicks on the needle falls down in pressure. When do I take the reading? When the compressor kicks on? Or when it kicks off? Because like I said, When the compressor kicks off, The pressure starts to climb up. So when do I take the reading of pressure on the guage?

Add some more. It's the release of refrigerant from the can that causes the needle to "go crazy". Eventually your lowest reading will come up. Take the gauge measurement when you're not releasing refrigerant.

I would only start troubleshooting if the second can of 134a doesn't do the trick.






More than likely, you need to add more 134a. Sometimes one can isn't enough. Your compressor cycle is too short. It shouldn't cycle every three seconds. Twenty seconds is more the norm.

Make sure you add refrigerant with engine on and AC on full blast.

Do you have the type of 134a with the pressure gauge and refrigerant all-in-one?

This is the first can, and the pressure reading is up to a little past "full". I really don't want to add more if the pressure is already full.
What would cause it to kick in and kick off at such a short time?
What happens to the air conditioning when you have to dump everything in the system?
Do I have to dump it all and start with absolutely no pressure? Could it be that the system is pefect and I just have to dump whats in the system and put fresh 134a in it?
Why would a system have to be dumped at all? Because the 134a inside of it is all used up?

I thought the exact same things about mine. I too didn't want to add refrigerant when the pressure level was within specs. I cautiously added a second can on 134a little by little. I found that the pressure stablized, and never went into the "danger zone" while at the same time accepting more refrigerant and making a noticeable difference at the dashboard.


Add some more. It's the release of refrigerant from the can that causes the needle to "go crazy". Eventually your lowest reading will come up. Take the gauge measurement when you're not releasing refrigerant.

I would only start troubleshooting if the second can of 134a doesn't do the trick.

I know that too much pressure will blow out the unit in a few different ways. I'm wondering if I should just take it to a tech and not ruin my ac system. I really don't have the money to replace anything on the blazer right now but the 134a.

well if you could tell me high side and the low side readings I could give you some kind of answer. With only this after market thing you have , you are flying blind. With ac pressure is everything in diagnotis.

I just found that out on another site. I now know that I have to have both readings anyways to get the problem solved. This gadget that I have only has the low side guage, and thats not enough. I guess that I'm taking her in to the shop.
I'm not guessing at anything with this, I'm not about to ruin the entire a/c system.
Thanks anyways guys for the help.