Is this normal operation manifold gauge set?

[Darrell]

Hey experts,

First, I know I really should just take truck to a real shop to get my AC working again, but I have the same DIY bug most of you have and it is not always about saving $

Rented vacuum pump and gauge set from AZ.
Replaced Schrader valve on Lp port.
Vacuumed out system, or at least though I did. System would not take a charge after vacuum .

I feel like hose fitting may be faulty but not sure what normal ovation is. My video probably asks my question better. Please take a look

Thanks!

https://youtu.be/9wwpPPWZtus

Topic

[Rob]

[quote=”OldToyota” post=170778]Hey experts,

First, I know I really should just take truck to a real shop to get my AC working again, but I have the same DIY bug most of you have and it is not always about saving $

Rented vacuum pump and gauge set from AZ.
Replaced Schrader valve on Lp port.
Vacuumed out system, or at least though I did. System would not take a charge after vacuum .

I feel like hose fitting may be faulty but not sure what normal ovation is. My video probably asks my question better. Please take a look

Thanks!

https://youtu.be/9wwpPPWZtus%5B/quote%5D
ya you have to have the vaulve open to get the pin pushed in teh ac system inorder for the ac gadge to work….
to better explain it … you have to turn the nob at the connector to open the system up the nobs next to the gaudges will open the yellow line…aka vacuum and fill line
also Just so you know and dont forget you need to add oil to the ac system… make sure you get the right type and amount…
here is a basic expression https://www.youtube.com/watch?v=Pdq8JAlct6s

[Rob]

chrisfix didnt explain about the gages to well but it will give you an idea…. basiclly when the compresor kicks on you will start to see the high side go up and the low side go down… and when it turns off you will see low go up and high go down showing the the system working correctly latter you can learn more about pressure levels and stuff… just make sure you have the high side closed when you fill it up… now if your not seeing the levels going back and forth accordenly you have your valives open both high and low side or the orfis tube or something else is bad… or you have have anoff coolent added to kick on the ac system or something else is wrong… let us know if you have any more questions

[Rob]

so you also know… you will have to have the coolent above the min level for the compressure to kick on,,,, when you start to see it getting right over the min lv you will see the compressor kick on for like 2 sec and turn off for like 8 sec and kick on for 2 and off for like 7 seconds… what you will see if the compressure sucking the coolent from the low and bring it to the high…. and the low go’s below the min lv and the compressor turns off again… FYI I want to tell you that and others that might be reading the form so you all know that is normal for it to do that untill you get it up to normal level’s

[Darrell]

Thanks Rob!

Ya, I’ve review both Eric’s and Chrisfix videos many (many) times.

My question was really about how the gauge it self works. Now that is cleared up for me and I cofirm the gauge set works by hooking it to a car with properly functioning AC.

Now I am faced with fact that compressor is not kicking in. This is 02 dodge Dakota 3.9 that has high presssure sending unit near hp port and not simple pressure switch that can be jumped on compressor itself.

In short I pulled and help a vacuum, (-27)
With engine OFF I dumped 1/2 12oz can has into high side per recommendations found for dodge on other sites. Apparently this system with sending unit must see min amount pressure on high side before it will engage compressor.

Then closed highside.

Started engine turned on AC. Condenser fan fires right up like it should, fuse is good.

Opened up low side. Low side sucks in 12 oz can but will take no more be alien compressor is not kicking on.

Gauge reads 80 low and 50 high.

Oh ya, I did add oil too.

This 134a was cheap ish but want to try and avoid vacuuming again if I can avoid it.
Or maybe I will admit defeat and take to shop.

Last summer everything worked. Before all this I confirmed low side Schrader valve was leaking and replaced it. So I don’t think any other components have issues but who knows.

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[Andrew Phillips]

Try jumping the load side of the A/C relay. That should kick it on to start the intake of refrigerant. If not, the compressor clutch or its wiring may be bad.

[Darrell]

Solved.

I feel kinda dumb here but discovered that the plug going to compressor was the issue. It looked like it was plugged in but was not really connected. Once I fixed that, compressor kicked in and system charged right up just like in Eric’s video.

Thanks for all the replies!

[Rob]

[quote=”OldToyota” post=170933]Solved.

I feel kinda dumb here but discovered that the plug going to compressor was the issue. It looked like it was plugged in but was not really connected. Once I fixed that, compressor kicked in and system charged right up just like in Eric’s video.

Thanks for all the replies![/quote]
LOL…. you got to use the gauge set to do your first diag on your AC system…. I think you might be still a little low… 80 I thought was just anof to start it up… but I would tell you to check… I could be wrong… maybe someone else could say what the level should be when its full

[Bluesnut]

You NEVER, EVER, put any refrigerant through the high side for several reasons.

[Darrell]

Yes, I hear you and won’t do it again. That said engine was off and can was upright so only gas could enter not liquid. It was suggested by others on a Dakota board as way to get compressor to kick in but as it turns out the issue was just the electric plug right at the compressor. If ever in same situation again I will check around with multimeter first.

At any rate, system is cooling great now I have about 35-40 lbs on low side and 225-250 on high. Air out of vents is nice and cold.

[Bluesnut]

Congrats on getting it going. Those pressures sound just fine.

The biggest issue with opening the high side into a tapped and open can of refrigerant is not so much slugging the compressor (which can certainly happen) but rather the chance of the can blowing up. The cans are not designed to take high side pressures.

Twice in the past in shops I’ve worked in I’ve seen can explosions and in both cases it was with guys who were very proficient with A/C work. For some reason or the other their minds wandered (problems at home, who knows….) and they inadvertently opened the high side valve on the gauges.

There was a loud shotgun BOOM sound and the mechanic would disappear in a large steam cloud. Luckily, both guys were wearing gloves and both of them wore eyeglasses anyway.
Otherwise they could have easily ended up with frostbitten fingers or worse; permanently blinded as refrigerant released into the atmosphere can blind someone in only a second.

While not politically or environmentally correct, a friend of mine used to bring a small case of Freon along when we would go target shooting. He used Freon at work in the electric motor shop to quickly freeze parts when needed. At the end of the session he would set up some cans of Freon and we would plink at them with .22s.
You should see one of those cans when it’s punctured by a bullet. It goes nuts in a huge steam cloud. Same thing with opening into the high side.

About 5 or 6 years ago I got a little careless on someone’s home central unit with R-22 and got a shot of Freon to the tip of my right index finger due to a balky connection on the gauges. That fingertip is still mostly dead today. Careless me wasn’t wearing gloves and got snake bit…… 🙁

[Author]

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