What should AC vent temp be?

Took a drive in the Viper last night and the AC did not feel that cold!

If I stick a infrared temp sensor and aim it at the vents, what should temp be?

On full AC, recirc or just AC, neither felt cool really. Yes it was a hot evening but still.... Somewhat remember it being colder in the past.

I guess the question is how do I know if I need a recharge?

Thanks!

45 degrees or colder right at the vent. Its very hard to check without pressure gauges, but the suction line (larger line) at the compressor should be ice cold when engine running and a/c on. Auto part stores sell 134a freon kits that just plug into the suction line port and have a gauge on them that will tell you if its low or fully charged. If its low, just add freon unitl it reads full.

Got bubbles in the sight glass? (Is there a glass on the GTS?). Bubbles mean recharge time.

Don't just add refrigerant. Take the car somewhere have the system discharged, vaccumed and recharged with the proper amount of refrigerant. I have tried just adding refrigerant but it never works as well as doing it right the first time. Some systems are very hard to get right and an over or undercharge will make the sytem perform poorly. I have a machine even if I didn't I would get it done right.

Wezbad1 said:

45 degrees or colder right at the vent. Its very hard to check without pressure gauges, but the suction line (larger line) at the compressor should be ice cold when engine running and a/c on. Auto part stores sell 134a freon kits that just plug into the suction line port and have a gauge on them that will tell you if its low or fully charged. If its low, just add freon unitl it reads full.

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Hmmm. Its not that cold!

jdeft1 said:

Got bubbles in the sight glass? (Is there a glass on the GTS?). Bubbles mean recharge time.

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That I will have to check. Good call.

JoelW said:

Don't just add refrigerant. Take the car somewhere have the system discharged, vaccumed and recharged with the proper amount of refrigerant. I have tried just adding refrigerant but it never works as well as doing it right the first time. Some systems are very hard to get right and an over or undercharge will make the sytem perform poorly. I have a machine even if I didn't I would get it done right.

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Valid thoughts.

With high humidity you may not be able to an ice cold vent outlet temperature. With that in mind, I would check up by the compressor for the leaking o-rings or leaking lines. The lines near the compressor/manifold leak where the metal crimps to the rubber hose, the last set of lines I replaced had a longer metal section and this positioned the "metal rubber joint" futher from the exhaust manifold. It is not always the o-rings as others may claim

Next I would drain the system and see if you are missing some of your 134a charge. If you are, add oil and dye, recheck after the system has been running. I would argue that the only true way to check an AC system for leaks is when it is in operation when temperature variations and vibrations come into play.

You should be able to see every part of the AC system. You can even see the evaporator if you remove the blower motor.

My money is on some sort of slow leak near the compressor.

Garrett

PS: lines are backordered

Thanks for the input Garron. I will do a visual inspection of the system.

The last time the system was recharged was in 2007. That was the first time it was done. Oddly the original dealer drained the system the original owner told me. He had never used it as the dealer he purchased it from said they drained it as they had it on display in showroom until 2004. Never made sense to me. Seems kinda dumb. LOL

Anyways, it was charged in 2007 so if it is leaking it is a slow leak for sure. But who knows. I will inspect and report back.

It is not uncommon for systems to lose a small amount each year - especially when lots of folks don't use their AC and seals go unlubricated. I've fought AC problems for 30 years or more and it is usually never easy to find a slow leak. That is why I suggested just discharging - evacuating the system, pulling a vacuum and letting it sit for 10 minutes or so. If it holds a vacuum, recharge with the proper amount. From what you said, you'll be fine and no repairs necessary. The best thing for cars we don't drive much is to be sure the system is run every time you use the car - monthly if possible. Whatever - good luck. Better to just recharge occasionally than to start ripping things apart but I know you like a challenge.

Thanks Joel. And yes I like challenges, but only when it is fun like swapping trannies because I want to. Not due to something breaking!

I went to Chuck, who found that the O-ring was leaking. He checked the entire system for leaks just to make sure that was it and then he drained and added the correct amount of refrigerant. He told me to always run the a/c for a few minutes whenever I take out the car, keeps the system working well. I do that (even in the winter) and mine runs quite cold since he did the work.

Good info right there. Thanks!

Thanks Ken!

Yeah....its got a leak!

So did you find a leak? I just serviced a Volvo V70 for a friend and it was 5 ounces low. This after a 9 month period. Out of a 2 pound charge that was enough to get the low pressure switch to turn the AC off. My '07 Accord was 3 ounces and it would cool right - on a 19 ounce charge. That is why I recommended recovering your refrigerant and seeing how much you have lost. Of course you could have a new leak that has emptied the charge but that will be easy to find if it went down right away. The 5 ounces over many months are harder to find especially when folks don't want to spend money to check the whole system and replace what is needed. But anyone who can disassemble massive trucks this is just an annoyance.

This is tonight's job. So nothing yet.

I'm in the same boat Mopar Boy

LifeIsGood said:

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In the pic, is the vent selector knob in the recirc or fresh air position? This has always confused me as the leftmost position seems to indicate recirc'ing outside air.

Voodoo Rob said:

I'm in the same boat Mopar Boy

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Sucky boat to be in let me tell you! LOL

Grisoman said:

In the pic, is the vent selector knob in the recirc or fresh air position? This has always confused me as the leftmost position seems to indicate recirc'ing outside air.

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From my Service Manual...

The leftmost position is 'Recirculate-A/C'...A mixture of outside air and recirculated interior air is cooled and sent through the instrument panel vents. This provides maximum cooling.

The next position is 'Air Conditioning'...Cool outside air comes through the instrument panel vents.

Thanks, Ken! Mystery solved (at least for this previously confused person).

Well, issue now solved. Seems the AC system had lost all its charge.

Went down to visit one of the few people I trust enough to touch my car (really, you did not know I was protective of my car? LOL) as I do not have the tools to vacuum an AC system prior to charging.

So I saw Garrett at Raceway Chrysler and it was inspected, checked, neither of us found anything so recharged with dye, inspected, still no signs, so waiting to see. I suspect a slow leak as the last time the system was charged was 2007.

So we will see. Just thought I would give an update for those who search the subject later.


And Garrett if you read this, thank you for being patient with special owners like me.


(Conversation was along the lines of: )

Garrett: Please drive the car in.

Robert: OK Sir!

I drive in and get out of car.....

Robert: OMG! Someone is about to touch my car!

Garrett: Its fine Robert. It will be better soon. I wont hurt it.

Robert: I know. If I did not trust you I would not be here. It was a few sleepless nights admitting there was a job I was not equipped to handle and needed to have someone help.

Garrett: Lets open the hood.

Robert: OMG! The car is being operated on!!

Garrett: Robert, its OK.

Robert: Your right. Were just opening the hood.

Garrett: Lets hook up the AC unit and see what pressure is in it.

Robert: OMG!!!!! The car is being hooked up to an automotive IV type of system! What if it was not properly sterilized and exchanges some sort of automotive virus!

Garrett: That is OK. Its just going to take the AC systems blood pressure.

Robert: OK.... (as he breathes again)

Robert: What was that beep!

Garrett: The machine turning on.

Robert: OMG! All is lost!

Garrett: This is going to be a long day......



Thanks Garrett. Your pretty good for a guy that owns a red Viper.

Garrett is the only "GUY" my viper is allowed to be operated on to, he is da-man!


We should all try to head over to the woodbridge La Paloma's on Hwy 7 and Weston Rd, saw two vipers there last week a cooperhead and a FE coupe, both very nice.....

Jman

For a guy who rebuilds steam locomotives, old bridges, and large Dodge trucks you are pretty sensitive. And, with all the stuff you have I can't believe you don't have a set of refrigerant gauges! Do you not want to be sure your beer is cold? I know you don't have Lucas refrigerators! You will need that AC when you come to the Dragon get together next year! Eh!

jman2 said:

Garrett is the only "GUY" my viper is allowed to be operated on to, he is da-man!



Jman

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That is for sure!

JoelW said:

For a guy who rebuilds steam locomotives, old bridges, and large Dodge trucks you are pretty sensitive.

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When it comes to my vehicles, I do get a little emotional. Truck, locomotive, or Viper.... they all have feelings.

And, with all the stuff you have I can't believe you don't have a set of refrigerant gauges! Do you not want to be sure your beer is cold? I know you don't have Lucas refrigerators! You will need that AC when you come to the Dragon get together next year! Eh!

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I do have a set. But the way I normally charge things with the small cans was deemed not good enough for the Viper. Have charged my trucks AC before, done other peoples vehicles, but when it comes to the Viper....I just couldn't do it half assed.


EDIT: And I did catch your little invitation and eh! Eh?

No would ever accuse you of doing anything half assed! I meant with gauges you would see you have no charge. I find I never do anything half ass - I'm pretty much in for whole assing! But come on down next year. I don't care for the Dragon but there are plenty of other great roads and I guess everyone ought to do it once. We'll see if we can start a Canadian aid for gas money fund. Of course the Candadian dollar is probably stronger than ours!!!

JoelW said:

No would ever accuse you of doing anything half assed!

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Thank you. I think.

I meant with gauges you would see you have no charge.

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True, but still could not vacuum the moisture out of the now exposed system.

I find I never do anything half ass - I'm pretty much in for whole assing! But come on down next year. I don't care for the Dragon but there are plenty of other great roads and I guess everyone ought to do it once.

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It is something I am considering.....

We'll see if we can start a Canadian aid for gas money fund. Of course the Candadian dollar is probably stronger than ours!!!

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Thats really thoughtful! LOL

Yes, Canadian money is worth marginally more (like a penny) but our fuel at like $5.20 or so per gallon ***** it all away!

We is all po foke up here now.

LifeIsGood said:

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As a side note, are the gen 1 & gen 2's the same with regard to the center dial on the HVAC controls? I was told to keep it turned to "red" because all it does is open the valve to get refrigerant to the heater core. If left on the "blue" the valve will close and your heater core will corrode faster.

Even with it on red, you can still get AC by turning the knob on the right.


Robert, hope your car is cold again!!

Originally Posted by JoelW

No would ever accuse you of doing anything half assed!

Thank you. I think.

Um, after seeing 5,346 pictures of your truck project, I don't think you can take it any way but positive support. And you're right you can't pull a vacuum but before I roll out my machine from its corner, I put gauges on first. If no charge or low pressure there, I can justify dragging sparky out of his corner for AC work.

If the last recharge was in 2007 and its now empty me thinks you have been using it what it was designed for, no slow leak just operator error like usual !

Newer A/C systems with rubber hoses they lose about 1-5% of the coolant charge per year via permeation in the rubber. On older systems up to 10%.