A/C Characteristics-Behavior?

[MarkD51]

About a year ago, I had my AC Compressor, and all other routine parts replaced, due to a leaky original AC Compressor on my 1997 Tahoe LT 4x4 4dr. (39K on the odometer)

Compressor was replaced with a new Delphi, (autozone) clutch gap appeared to check out fine at .020", new Drier-Accumilator, new stock Yellow Orifice tube both from GM, system was flushed, Compressor was first manually bench primed and professionally evacuated, charged, first with 2 lbs of 134a, then an additional .2 lbs added a few days later, bringing the total refrigerant amount to 2.2 lbs.

New Port Shrader Valves, and all seals replaced with new, no leaks. Proper Oil (I forget which offhand at the moment was used, and a UV fluid was used for future detection of any possible leaks. All appears fine, the professional appeared to do a quite through and careful job.

Upon first fire up of the vehicle from cold, the Compressor will auto cycle on and off regularly for a number of minutes, stay engaged for perhaps 10-12 seconds, then kick out for about 20 seconds. There is a slight variability, dependent upon outside temps, on average last summer, temps were in the mid 90's when this was all done, checked, and noted.


It will cycle like this for perhaps 10 minutes under my carport in the shade, then when pulling the truck out, and it's now out in the sun, the compressor on full Max setting then stays engaged, and maintains staying engaged without cycling at all. After that, under such heat conditions all then appears perfectly fine, the Compressor stays engaged,

Temps I'm getting at the Vents with a dig. thermometer on Max, high Fan speed, are running between 40-42 degrees. On a rare occasion I've even seen the Thermometer dip to as low as 39 degrees.

So then, may I ask, is this normal where the Compressor will initially cycle like this upon warm up for the first 10 minutes or so? Is this the system's way of first distributing the Oil throughout the system?

Although I am the original owner, I honestly cannot remember how the truck's AC behaved from when new, and if it did this?
Thanks, Mark

 

[SunlitComet]

It sounds fine so far. but do a performance test to be sure you have a excellent charge.

BTW, is bench priming a compressor?

 

[MarkD51]

It sounds fine so far. but do a performance test to be sure you have a excellent charge.

BTW, is bench priming a compressor?

I'm certainly no AC expert, but as I understand, when a system is totally purged, and "supposedly" all oil is then removed, the Compressor then should be given a dose of oil direct into the Compressor. How many ounces I forget? A couple?

Then the tech manually rotated the Compressor by hand on the bench before installation on the truck.

The issue of "thinking" you have the system totally drained of refrigerant oil may be an issue where it won't totally be as I understand it, no matter how much PSI of air you blow through the system.

That a quantity of oil will still remain in the Condenser. I've read comment that the only way to fully insure all oil is out, is to physically remove the condenser, and gravity drain it.

This was not done on my truck.
Mark

---------- Post added at 07:37 AM ---------- Previous post was at 07:21 AM ----------

It sounds fine so far. but do a performance test to be sure you have a excellent charge.

BTW, is bench priming a compressor?

What would a "performance test" be? There was a follow up a couple weeks later, gauges confirmed no loss of refrigerant, still was at 2.2 lbs, and all lines connections-fittings checked with UV Light.

I would assume temps at the vents running between 40-44 degrees on Max would be good?

As for possibly retro-fitting a different Orifice Tube, for high summer temps as we have here in the SW Desert, we had found that this larger-longer Orifice Tube would not physically fit at the condenser. So just a new stock Orifice (yellow) Tube was used.

The original Orifice Tube was not bad, the original Compressor only leaked at the housing, didn't disintegrate or such.
Mark

---------- Post added at 07:41 AM ---------- Previous post was at 07:37 AM ----------

What was surprising, and had me shaking my head, was that the original AC Compressor on my Tahoe was a re-manufactured unit. I am the original owner of the truck, and it came with such from the factory.
Mark

 

[SunlitComet]

Not really called priming at all just adding the needed oil to replace what may have been lost and just turning it will not get it all coated properly. It needs to be installed and run. The oil in the system will do its job then. Will pm you the test.