# Using an Ac Vacuum Pump, Having Issues **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** chevrolet, airconditioning, silverado1500\ **Created:** [June 21, 2020, 2:21am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092 "2020-06-21T02:21:07Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:21am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/1 "2020-06-21T02:21:07Z")
Just have a general question about ac vacuum pumps. I tried to use one the other day for the first time, and couldn’t figure out how to get the pump itself to hold pressure. - First I got a junky parts store rental pump and followed instructions to check oil. 1. Block off suction port, let run and check oil level 2. Slowly add oil as necessary As soon as I turned it on, freon started blowing out of the oil pour cap, so i tightened it down and tried again. Same result. So I figure it’s just a shot pump and bring it back. They swap it out for a new in box unit and I bring it back and the same exact thing happens (but with just air this time.) Am I just having bad luck or is this normal? ---
**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:** [June 21, 2020, 2:26am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/2 "2020-06-21T02:26:13Z")
Is the AC system you’re connecting the vacuum pump to void of refrigerant? Tester ---
**Author:** ![Jack-Dak87](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jack-Dak87](https://community.cartalk.com/u/Jack-Dak87)\ **Post date:** [June 21, 2020, 2:27am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/3 "2020-06-21T02:27:26Z")
Need more info. ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:32am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/4 "2020-06-21T02:32:35Z")
Didn’t even make it to that point. I was just test running the pumps per instructions and number one blew freon from the oil cap and number two blew air since it was new and unused prior. ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:33am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/5 "2020-06-21T02:33:12Z")
What more info? That’s all that happened. ---
**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:** [June 21, 2020, 2:35am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/6 "2020-06-21T02:35:49Z")
Are you saying the AC system still has refrigerant in it? Tester ---
**Author:** ![Jack-Dak87](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jack-Dak87](https://community.cartalk.com/u/Jack-Dak87)\ **Post date:** [June 21, 2020, 2:37am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/7 "2020-06-21T02:37:28Z")
When you write: “I tried to use one the other day for the first time, and couldn’t figure out how to get the pump itself to hold pressure”, what exactly did you do other than “tried to use one the other day” that resulted in the pump not holding pressure? ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:42am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/9 "2020-06-21T02:42:55Z")
This is from my original post " \* First I got a junky parts store rental pump and followed instructions to check oil. 1. Block off suction port, let run and check oil level 2. Slowly add oil as necessary As soon as I turned it on, freon started blowing out of the oil pour cap, so i tightened it down and tried again. Same result. So I figure it’s just a shot pump and bring it back. They swap it out for a new in box unit and I bring it back and the same exact thing happens (but with just air this time.) Am I just having bad luck or is this normal?" ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:44am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/10 "2020-06-21T02:44:19Z")
Yes it does, but I didn’t make it that far. I was just adding oil/testing the pump prior to hook up. ---
**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:** [June 21, 2020, 2:52am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/11 "2020-06-21T02:52:28Z")
So? Are going to repay the parts store for the vacuum pumps you ruined? I can believe it! I’m roaring my ass off! Tester ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 2:54am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/12 "2020-06-21T02:54:35Z")
So you’re not supposed to turn them on? ---
**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:** [June 21, 2020, 2:58am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/13 "2020-06-21T02:58:07Z")
> [@blueredblue](#): > > So you’re not supposed to turn them on? Not with refrigerant in the system! Tester ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 3:01am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/14 "2020-06-21T03:01:02Z")
I’m pretty sure you don’t understand me. The instructions say to test run the unit (without being hooked up) to circulate and check oil levels. So they weren’t even hooked up to a vehicle or cooling system. Simply plugged into an outlet. ---
**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:** [June 21, 2020, 3:09am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/15 "2020-06-21T03:09:20Z")
No! I totally understand you. And everything you’ve stated so far has nothing to do with normal AC service or expectations. Tester ---
**Author:** ![Jack-Dak87](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jack-Dak87](https://community.cartalk.com/u/Jack-Dak87)\ **Post date:** [June 21, 2020, 3:13am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/16 "2020-06-21T03:13:03Z")
Did you hook it up to your AC system when “freon started blowing out of the oil pour cap”? If not, where did the freon come from that blew out of the oil pour cap? ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 3:15am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/17 "2020-06-21T03:15:15Z")
So you don’t understand. My question was specifically about ac vacuum pumps, nothing to do with servicing an ac system. Just like if I asked “Why does my floor jack keep falling down even when in the tightened position with no weight?” And you ask “Well how much does the car weigh?” ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 3:16am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/18 "2020-06-21T03:16:48Z")
No I didn’t even make it past oiling/test starting the unit solo/ unhooked from anything. I assume it was freon, it was a cold rising gas. ---
**Author:** ![blueredblue](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@blueredblue](https://community.cartalk.com/u/blueredblue)\ **Post date:** [June 21, 2020, 3:18am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/19 "2020-06-21T03:18:12Z")
The oil also had a green tint in the sight glass if that helps. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 21, 2020, 4:01am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/20 "2020-06-21T04:01:31Z")
> [@blueredblue](#): > > As soon as I turned it on, freon started blowing out of the oil pour cap, so i tightened it down and tried again. Same result. There is no refrigerant in a vacuum pump, if the pump was stored upside-down you might see a mist of oil discharged from the exhaust vent but that doesn’t indicate failure. ---
**Author:** ![Jack-Dak87](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jack-Dak87](https://community.cartalk.com/u/Jack-Dak87)\ **Post date:** [June 21, 2020, 5:29am UTC](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092/21 "2020-06-21T05:29:13Z")
So if you didn’t connect to an ac system, and were just checking the ac vacuum pump, where did the freon come from? [Next page](https://community.cartalk.com/t/using-an-ac-vacuum-pump-having-issues/166092.md?page=2)