a/c issue, works for a while

[adbaker]

04 Silverado Ext. 5.3l

Manual Dual Climate Control

 

 

Early summer i had my a/c leak tested, evac'd and filled. It had been running poorly (barley cold). No leaks were found but the system was low. I tested it out after the fill and it seemed to cool nicely, but, and this is just a seat of the pants analysis, it didn't seem as cold as past years. I don't use the a/c much, usually only when the wife and kids are in the truck with me, so when i say this problem seems recent, it could very well be since the system was re-charged. Basically the a/c stops cooling after a while, sometimes 30 mins to an hour. It doesn't blow heat, just becomes ambient, musty and damp, on both the passenger and drivers side. I can switch the sytem off, keep driving for 5 mins, switch it on and it will cool nicely. If i don't turn it off, it doesn't start cooling again, at least not within 15 mins. This has happened a few times, driving in heavy stop and go traffic as well as on the highway, pulling a trailer or not. I'm going to bring the truck back in, the shop said they'd pressure test it again but i was wondering where else i might look for a problem. Two other thing i've noticed, my recirc door actuator doesn't work, the button stays lit but nothing moves, and it seems like i don't have huge puddles under the truck on really muggy days like i used to. I can lift the hood and condensate is dripping out the line, but not a whole lot.

 

Any help would be appreciated.

 

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[00Silverado4x4]

I'd get your system check for refrigerant charge again. It's possible you've developed a slow leak.

[txab]

I'd check actuators and check to make sure the clutch is engaged during the periods where you seem to be not getting any cooling

[8.1HD/ALLISON]

Check the pressures. Sounds like it could be low.

[Wires]

It sounds like it's freezing up after continuous operation. Maybe the A/C clutch isn't cycling? If it's run 100% of the time, the condensor will freeze, and then you just get cool air until you turn it off and it thaws again.

[Wolfmanjohn]

With symptoms/history like that, I'd be looking for excessively high pressures that build slowly due to air in the system. Yes, even though it was "evacuated" (quotation marks because EPA says that has to happen when the system is opened).

[Rayaz_XL]

It is possible your AC system may have a slow leak, or even be overcharged. The AC system will not operate if it senses pressures too low or high. If you get a pressure gauge by Duracool from Wal-Mart you can check if pressure is somewhere between 25-38p.s.i is perfect, and no more than 45 p.s.i. I beleive the gauge may need a can screwed on to block off your aéc refrigerant from leaking out. If pressure is low try a can of Duracool which is compatible with r12, and r-134a refrigerant and its $15. If it leaks out, buy the stopleak sealant for $25 works great, and refill system. Otherwise bring to a trustworthy qualified shop to inspect and do it right.

[adbaker]

Thanks for the advice, i'm off this week, i'll bring it back to the shop where they did the leak test the first time. They told me to come in anytime and they'd throw the gauges on and pressure test it at no charge. Weird this past weekend, we left for a camping trip friday at noon, hot day, kind of muggy and the a/c would work for 10 minutes then stop, i'd switch it off for 2 minutes and it would work again for about 10 minutes or so, i left it off for a while (maybe 20 minutes) and when i switched it back on it would only run for 10 again. Today on the way home, it ran the entire two hours without a problem, less humidity today though, cooler day too. I'll fill everyone in after i get it re-tested. I'll ask them the pressure they're getting too...@Wolfmanjohn, what would be considered excessively high? ...and i'm assuming its a high measure at the low pressure switch?

 

Oh, and i've tested all the actuators, they're functioning fine, with the exception of the recirc door. It doesn't move at all.

 

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[Wolfmanjohn]

A high pressure reading of ~400-450 psi at the high side discharge would kick it off.

[adbaker]

First off, sorry to drag up an old post but I figured this is the best way to give everyone the history.

Second, sorry for never updating the post. For the rest of last summer, the a/c seemed to work fine for the few times I used it, i never brought it back in to the original shop.

 

Enter summer of 2013...I have no a/c at all. The compressor wasn't kicking on. I started by jumping the low pressure switch and it kicked on immediately the coolant line got cold and frosted up, no cooling inside though. I grabbed a new low pressure switch and hoped this would solve my issue. No dice, although I can hear the compressor cycling quickly, maybe about 2 or 3 seconds, on off, still no cooling. O.K., sounds like a low refrigerant situation but I'd like to confirm with anyone that can help. I borrowed a buddy's low pressure side gauge, one of the ones you can grab at the parts store to top your systems up. With the compressor cycling quickly, i would see readings of 50 to 5. I'm going to assume that this proves I have low refrigerant? Do these numbers mean basically empty? If this is the case, I'm thinking about topping it off with duracool or red tek and some leak seal. They don't let us buy top up r134 in stores up here.

 

Unless of course someone might know better.

 

thanks

 

Adam

[txab]

Fix the leak properly. Don't use the fix a leak crap. Only causes more problems

[diy_darryl]

Sounds exactly like low refrigerant to me. Most common leak is from O-rings. You can buy an A/C O-ring kit for your vehicle for not too much money. You'll need the tools to disconnect the lines to replace the o-rings. Don't forget the ones on your compressor. You'll need to vaccuum it down after this to remove moisture and to leak check. Replace the receiver/dryer while you are in there and add an oz or so of refrigerant oil if you replace the dryer. Another common area that can leak is your schrader valves so hit them with some leak detector or soapy water when done.

[adbaker]

Thanks for the replies everyone. The shop last year put dye into the system, I noticed when I swapped the low pressure switch, the valve underneath spurted a little green at me. I borrowed a UV light from work but haven't been able to track down the leak yet. No bubbling from soapy water sprayed either. There's still some pressure in the system so it should still be leaking somewhere. I'll keep looking though, gotta find the leak and change the part before I evac and refill.

 

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