# 2002 GMC Sierra ac not working correctly **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** airconditioning, gmc\ **Created:** [April 14, 2019, 12:34am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464 "2019-04-14T00:34:48Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 12:34am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/1 "2019-04-14T00:34:48Z")
I am having issues with my trucks ac. I filled it up with Freon after it blew hot. And it blows cold for a few days then stops, initially found that the low side valve was stuck open so it might have leaked out. I replaced the valve and filled it again and it did the same. Found that when I filled it up after fixing the valve the compressor would not shut off so we took some Freon out to get it to switch on and off because the line was freezing. I’ve also replaced the orifice tube. Any clues? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 14, 2019, 12:37am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/2 "2019-04-14T00:37:53Z")
> [@David5292\_150742](#): > > I’ve also replaced the orifice tube. Was a vacuum pulled on the system to remove any air/moisture? Tester ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 12:38am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/3 "2019-04-14T00:38:52Z")
We emptied Freon with a machine at my dads job, so it does vacuum it ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [April 14, 2019, 12:43am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/4 "2019-04-14T00:43:02Z")
How many inches of vacuum did it pull, and how long did you hold it there? Also, if you didn’t replace the receiver/dryer, you should have. ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 12:43am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/5 "2019-04-14T00:43:53Z")
Not exactly sure, when we emptied it, we let it vacuum for 30 minutes ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [April 14, 2019, 12:46am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/6 "2019-04-14T00:46:04Z")
You need to hold 25" of vacuum for 30 minutes to vaporize all non-condensables. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 14, 2019, 12:49am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/7 "2019-04-14T00:49:45Z")
You need one atmosphere, (29.92" Hg) to evacuate an AC system. Tester ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 12:51am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/8 "2019-04-14T00:51:09Z")
I’ll have to replace the accumulator, might try vacuuming it out again, and seeing if there is a leak also. Cause I keep having to put Freon in. Compressor doesn’t make any unusual noises and cuts off and on so I don’t think that would cause anything ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [April 14, 2019, 12:51am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/9 "2019-04-14T00:51:12Z")
Tester is correct. I should not post after my second martini. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 14, 2019, 1:12am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/10 "2019-04-14T01:12:51Z")
What did the orifice tube screen look like? Tester ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 1:16am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/11 "2019-04-14T01:16:29Z")
It was pretty dirty, some small pieces of something on it ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 14, 2019, 1:20am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/12 "2019-04-14T01:20:15Z")
That’s too bad. That’s an indication that the compressor is failing. The only mechanical part of the AC system. Tester ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 1:28am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/13 "2019-04-14T01:28:35Z")
From it being dirty? The orifice tube didn’t look like it had any metal shavings on it or anything, more like dried about oil ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [April 14, 2019, 1:31am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/14 "2019-04-14T01:31:11Z")
Since your dad seems to be equipped with tools . . . inject some uv dye through the low side, while the engine is idling and the ac compressor is engaged Eventually, an ac component will turn green . . . and that is the cause of the leak ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 1:32am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/15 "2019-04-14T01:32:27Z")
I got some Freon with sealer/uv dye in it and I didn’t see any green anywhere besides the low side valve where I put it in at ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [April 14, 2019, 1:33am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/16 "2019-04-14T01:33:48Z")
are you using the correct black lamp and yellow lenses to look for the leak . . . ? Keep in mind that some components aren’t easy to see . . . such as the evaporator and the back side of the condenser, which faces the radiator ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [April 14, 2019, 1:35am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/17 "2019-04-14T01:35:45Z")
Look up automotive AC black death in your search engine. That’s how it starts. Tester ---
**Author:** ![David5292\_150742](https://avatars.discourse-cdn.com/v4/letter/d/77aa72/32.png) [@David5292\_150742](https://community.cartalk.com/u/David5292_150742)\ **Post date:** [April 14, 2019, 1:36am UTC](https://community.cartalk.com/t/2002-gmc-sierra-ac-not-working-correctly/138464/18 "2019-04-14T01:36:17Z")
Yes, we used it