'10 LT A/C issues

[1-oh-Hoe]

2010 tahoe LT with dual climate and rear air. Tri zone?

No OBD codes,no CEL, autostart FINALLY works. But the air is marginal at best. I live in SWFL too, so its brutal.

When I have the ac on it will blow cooler than outside,but I can hear the clutch cycle. When I bought it the relay was jumped "without me knowing". It blows ice cold like that. But sometimes when I stop and restart like running errands it will blow warm. Not cool.

I have a VCX diag Tech 2 clone that I can get to communicate with vehicle. But zero idea how to use it to troubleshoot. Or even if I need to download some special additional software or if the software they sent was enough. Blend doors/actuators/idk where to start... Its been a while but I remember the ABS bleed option and ive programmed Keyfobs using it. Ive also done the hvac fuse pull reset.

Hooked gauges up after a long drive and everything was warm. It was about 80 ambient 70%humidity. The gauges would drop when compressor clicked on. From around 95 low to around 75 in a second then it would compress slower to around 65 in an additional second. High side is around 125 then 150.Clutch cycles everything starts to equalize and then compressor clicks back on. When Im listening its a constant on/off,on/off.... like 3 seconds apart. This is with relay in,not jumped. I havent tested it any other way. Im apprehensive using it because I dont want to really break something.

Cooling system has been upgraded and 700w fans "k5l" installed over the 500w it had. Trans and coolant temps are fine. Have aftermarket gauges on top of factory.

I dont have a cycle switch on the accumulator. So from what I gather its near the compressor.

Sorry for the ramble. Trying to be thorough...

Where do I go from here? Id rather test than throw parts at it.

 

[blondie70]

Have you tried putting refrigerant into it ?

 

[1-oh-Hoe]

Have you tried putting refrigerant into it ?

I was concerned about overcharging. This is my 1st time messing with auto air. I wanted to get opinions before breaking something through ignorance.

 

[kbuskill]

I was concerned about overcharging. This is my 1st time messing with auto air. I wanted to get opinions before breaking something through ignorance.

From what you are describing it is short cycling which is the classic symptom of low refrigerant. Buy a can of freon with the little gauge attached and charge it until it is in the green. Compressor should stop short cycling and you should have cold air again, assuming there are no other issues.

High side pressure should be roughly 2.5 times Ambient air temperature. So at 80° Ambient, around 200 psi on the high side.

 

[1-oh-Hoe]

From what you are describing it is short cycling which is the classic symptom of low refrigerant. Buy a can of freon with the little gauge attached and charge it until it is in the green. Compressor should stop short cycling and you should have cold air again, assuming there are no other issues.

High side pressure should be roughly 2.5 times Ambient air temperature. So at 80° Ambient, around 200 psi on the high side.

I checked static pressure and it was 95psi low and and 100high, around 84 ambient before starting. When i started it up it ran fine for about 3 mins with low at 47 and high at 140. After those few minutes it started cycling again. I added 12 Oz and it still cycled. I jumped the relay to get a reading and low was 60 high was 151. Replaced the relay and started cycling again.