Losing my cool with an A/C problem

[OC2Vegas]

Ok someone help me....PLEASE!

I will start at the begining so everyone has a clear understanding.

In December it snowed in Las Vegas(Really, It did) and my 03 Silverado had a fight with a BIG gate post.

Trucks front end was ripped apart that night:

Grill, Hood, Bumper, radiator, Condensor, Lights, radiator core support, Fan Shroud, and all misc parts in between there.

Went to Chevy dealship by Flat Bed to have frame checked out.

Came home 4 days later, and was put back together within the next 4 days.

The A/C system was "open" for a few days, nothing major.

Didnt need the A/C system until June.

Tried refilling the R-134 and oil, following directions to a "T".

Seamed to work "OK" cooled down to mid 60's sometimes lower.

In late June the weather started gettin a bit warmer and it wouldnt cool quite as low as before. Adjusted the R-134 Levels all seemed ok, but still wouldnt cool that low.

Took it to the shop(Maybe I missed something), shop couldnt figure it out..."ah it might be this, it might be that"

Now its REALLY HOT (113 Today) and it just wont cool past 75-80.

I have noticed that when I turn the truck on the Compressor cycles like it should, Temp starts dropping.

Compressor stops cycling, continues to cool down.

if you rev the gas are hold it above idle or just driving down the street the compressor again starts to cycle and the temp of the air goes up a little.

Stop at a light and the compressor stops cycling and the temp starts to cool again...Frustrating!

cant figure this out but dont have the $$ to spend to go to dealer...

ANY ADVICE or suggestions from all of you would be great!

[2000CAYukon]

If the a/c was open for a few days, the accumulator should have been replaced. Also, too much (or too little) R134a can cause it to not work right. The only way to get it right, is to drain and refill with the correct amount.

I would drain, replace accumulator and orifice tube adding the correct amount of oil for an accumulator replacement, then refill.

//2000CAYukon

[99redsilverado]

i agree accumulator should be replaced...but the correct word instead of drain would be Evacuate...then recharge...with a UV dye and then about a week or so later, check all connections with a UV light and if its bright its leaking there....might be o ring, loose fitting, cracked fitting, etc. id take it to a shop unless you have the ability to pull a vacuum on the system...good luck and welcome to the forums!!

[chuck16]

It also could be a clogged strainer or drier. Being that your system was open it could have accumulated dust or something inside and clogged your lines up not letting all the R134 through. I miss the days of sight glasses. You use to be able to look at the condensor core and see if you had bubbles in your system or not.... Sorry to hear about your woes...

[OC2Vegas]

Is there any explanation on why the Compressor turns back on when the RPM's go up?

Is it possible that with the system open for a few days and then recharged that there is still air in the lines? And if there is air, is there anyway to remove it while recharging? or before by placing a vac. on the system prior to charging.

I would think that when the system was put back together that it would be filled with Air, and when the system is being charged, the air has no where to go. So it seems possible that the system is under-charged with R134a because the air is taking up some of the "room" in the system that there should be R134a in.

I might be crazy, but it just seems logical to me.

[3wbdriver]

My '04 stopped cooling altogether 3 weeks after I bought it. I took it to the dealer and they replaced the low pressure bypass switch. They said it was not an uncommon problem with this model, and even after warranty the switch is fairly cheap, and easy to replace. I watched them do it, and I wasn't there more than 10 minutes. You might look into that also.

[2000CAYukon]

Did you add the R134a or did a shop do it after it went back together. Whenever a system is opened, a vacuum pump is used to get all the mositure and air out of the system. Then r134a can be added.

The pressure cycling switch (located on the accumulator) shuts off the compressor when the pressure drops below a certain point and then turns the compressor back on when the pressure is high enough. During this time, r134a accumulates in the accumulator. The compressor kicks on and r134a is fed into the compressor. The cycle keeps on going.

If it your compressor is not kicking on at idle, it could be a bad switch, or you are low on r134a. The fact that it kicks on with RPM leads me to believe that the pressure switch is flakey. The pressure switch can be removed without evacuating the system.

//2000CAYukon

[OC2Vegas]

Bypass switch was replaced shortly after i bought mine too. But when it went all it would do is blow HOT air out. It is still cooling just no where near where it should be.

No the system was never evacuated under vac. it was just charged.

The Compressor does come on when the truck is turned on, but stops, i am assuming when it has reached pressure.... Why it turns back on with RPM'S has me scratching my head...

[2000CAYukon]

Originally Posted by OC2Vegas

The Compressor does come on when the truck is turned on, but stops, i am assuming when it has reached pressure.... Why it turns back on with RPM'S has me scratching my head...

The PCM may be controlling the compressor when the RPMs get to a certain point. A GM Tech that is familiar with the 2003 should be able to answer that.

I know that with my 2000 when it gets really warm (over 100), the a/c does not work as well at idle. Of course, in San Jose, that does not get to 100 as often as it does in Vegas.

//2000CAYukon

[OC2Vegas]

Anybody have an idea on how to evacuate the system while under vac.?

[2000CAYukon]

Originally Posted by OC2Vegas

Anybody have an idea on how to evacuate the system while under vac.?

Any automotive a/c shop can do this for you. Otherwise, you need to buy/rent a vacuum pump.

When my compressor went out on my 96 Impala SS, I paid a shop to evacuate any r134a in the system. Went home and replaced compressor, accumulator and orifice tube (also flushed the system). Went back to the shop, they put it under vacuum and made sure it held the vacuum for 20 minutes. Then they added the correct amount of r134a. I think I paid around $50 total to the shop. The parts I bought myself.

//2000CAYukon